Climate change in northern Canada (mid-20th century to present)

M.T. Cranium

These are postings that originally appeared on the Net-weather forum. Due to the hostility of moderators and administration there (because of my refusal to accept all aspects of the IPCC theory of climate change) I am copying my material from Net-weather and posting it here for safer keeping. I suspect that the next move to be made against me will be removal of my postings or termination of account, so I want to act quickly to get ahead of that possibility doing permanent harm to the research material.

_________________________________________________

I am as interested in arctic climate change as anyone, but a lot of discussion goes on without much reference to actual data.

Cambridge Bay is located on the southern coast of Victoria Island, a huge and largely barren arctic island about the same size as Great Britain, and located between 68 and 73 degrees north latitude in the western arctic. The Inuit population of the eastern arctic have their own territory (Nunavut, or NU) and Cambridge Bay, a town of about 1500 population, is just inside its border while the western third of the island (and adjacent Banks Island) are in the Northwest Territories (NT). The weather station began operations in 1929 -- the airport is near sea level and just southwest of the town -- and the data from the years through 1939 are spotty at best. There are not enough continuous periods of observation to draw many conclusions about the local climate in that period.

Since 1940, the weather station has operated almost continuously, with a few missing stretches that must have been caused by staffing problems or perhaps loss of data. I have treated the data as continuous because very few days are missing, except where noted.

(added later _ After this section on Cambridge Bay, I will be adding similar data for Resolute, located in the central arctic islands to the northeast of Cambridge Bay _ look for that added information in the next few days).

The objective of this study is to pick some major climate features and study how these have varied, if at all, from the 1940s to the present time. I had read anecdotally that the climate in that region had warmed almost as much as the celebrated (wrong word probably) increases around Svalbard. The climate of the western Canadian arctic has little direct oceanic influence and is therefore probably more indicative of air mass frequency than changes to local modifiers. If ice cover has changed over the Beaufort Sea, it should be noted that Cambridge Bay is about as far from that body of water as Berlin is from the Atlantic Ocean, although similarly exposed to its west by mostly flat undulating terrain of Banks Island and then western Victoria Island.

Overview of the climate

Winter is of course very long and begins around the middle to end of September in most years with frequent snowfalls. Temperatures drop gradually through the range of -5 to -20 C by early November, with day to day variations. This first part of the arctic winter is windy and frequently stormy although snowfall amounts are typically light given their frequency. In a normal winter, about 25-40 cms of snow has accumulated by New Years and this coverage remains almost static but usually slowly increasing, as small top-up amounts in January to March are somewhat compensated by sublimation or settling (or redistribution by wind but that could also increase snow depth). Temperatures typically keep dropping through the two months of continuous darkness mid-November to late January, and bottom out in late January or February which is often the coldest month of the winter, with long spells around -35 to -40 not uncommon.

Lighter winds are noted by this portion of the arctic winter; it should be noted that despite tales of monster storms hitting arctic expeditions, most of the peak wind gusts noted at this and other arctic weather stations falls in the same range as we see in southern Canada, 80 to 110 km/hr. Wind gusts that strong seem to occur about three or four times a winter and often from directions between northwest and north-north-east, as the strongest low pressure systems of mid-winter are likely to be either heading due east (north of YCB) or situated off to the east around Resolute and looping around or dropping southward in the vicinity of the central arctic islands.

While March and April are hardly "spring" as we would know it, the human population finds the conditions more amenable to travel and outdoor activity, as there is often sunshine in the rapidly increasing daylight hours. By early May it is becoming light almost alll through the night and then comes two months of continuous daylight. While there can be significant storms in these three months, the average snowfall often drops off to 5-10 cms a month from its peak of about 15-25 cms in the early winter. There can be a secondary peak in snowfall just before the winter (or spring) gives way to arctic summer in early June. In a few years as noted, large snowfalls occurred in May or even early June before the main snowmelt began, but in other years this begins in the last few days of May. Going back through the entire winter-spring period, it can be added that rainfall almost never falls past mid-November at the latest or before mid-May, and there are seasons where roughly equal amounts of rain and snow fall, often on the same day, as a frequent synoptic pattern is for low pressure to track east along the northern Canadian mainland.

The summer is quite brief but can be intensely warm for the latitude. Heated air masses of Pacific origin from the Mackenzie valley region to the southwest are drawn in and suffer only slight cooling from having to cross narrow straits south of Victoria Island (and numerous mainland lakes that remain frozen into July). While lakes are less widespread on Victoria Island, any that are present can remain frozen almost into August and then start refreezing in late September. The summer weather regime begins to take hold in fitful periods of alternating damp chill and warming sunshine in late June, typically one or two days will reach 14-17C by then. With no darkness at night, the overnight lows are mild for the most part. By July, usually the warmest month, some long periods of warmth can be expected with highs into the 20s. However, even then, cold and rainy intervals are possible, as well as dank foggy spells. Snow is very rare from June 21st to August 15th. It tends to show up in about one third of late Augusts and in almost all Septembers. A typical September in Cambridge Bay would be rather similar to a November in the Lake Superior region of southern Canada, with bursts of heavy snow, some rain, and large swings in temperature, copious cloud and brief clear intervals that are much colder (especially if snow has fallen) but a rapid decline in temperature overall.;

This is a link to the 1981-2010 normals and period records (1929 to present) for Cambridge Bay.

http://climate.weather.gc.ca/climate_normals/results_1981_2010_e.html?stnID=1786&autofwd=1

Some of the extremes such as the highest temperature (28.9 C in 1930) occurred in those brief intervals of data collection before this study period begins in 1940.



Key Climate Indicators chosen for study

1. Coldest monthly mean temperature (winter rather than calendar year)

2. Lowest winter temperature

3. Deepest winter snow pack

4, Date of last snowfall

5, Date of last air frost

6. Change in snow cover reported April 30 to May 31

7, Warmest monthly mean temperature of summer

8. Highest summer temperature

9. Date of first air frost

10. Date of first snowfall

11. Date of first -20 C reading

Tables of these elements will be provided next. The snowfall season for dating first and last snow events arbitrarily runs from August 1st to June 30th so that any July snowfalls are noted by asterisks below the tables (there are only a handful). Any measurable amount is acceptable, traces are ignored.

The source of all data is Historical Data section of the Environment Canada website, monthly or daily data as required,

Analysis of trends and variability follows the data tables.

Using 1940 (or first reported year) as a guide, this is how to read the table.

Element 1 __ -296F __ Feb mean -29.6 the lowest monthly mean of 1939-40.

Element 2 __ -467F __ Min of -46.7 Feb coldest reading of winter 1939-40.

Element 3 __ msg ___ maximum snow depth from end of month which is the only time actually reported 1949 to 1954, or any other date if can be established -- for example in 1950 with 43 cm at end of April and May, estimated 46 cm on May 20 as first 20 days had 5 cm snow in small amounts, and sustained cold, then last eleven days little snow and some minor melting likely, so best estimate would be a slight increase to 20th then a decrease back to the late April value -- as there was no snow depth data until 1948, this column is "msg" until data begins -- where available, the report is an amount in cms followed by a date in number form, e.g. 46/140 for 1950 means 46 cm on May 20. When looking at these dates, remember that every fourth year (with data) after 1944 will be a leap year. Also, the date cited is the last date of the spring season where the amount is sustained for more than one consecutive day (for example in April 1962 the amount 25 cm was reported every day of April so April 30 is chosen as the date).

Element 4 __ 167 __ last snow of season June 15th -- entry is once again date number, typically in June when day 152 is June 1st and 181 is June 30th (non-leap-year). (153 to 182 in leap years). An asterisk beside this number will indicate a July snowfall event, details will be provided at end of tables. Since first posted, I have changed the logic of this to use the July date in the table and make the comment to indicate the earlier pre-July date. Basically, a snowfall season at Cambridge Bay normally winds down in early to mid June and resumes in late August. July and early August events are sometimes outliers, and sometimes more connected to the fading or emerging winter seasons depending on details.

Element 5 __ 205 __ air frost occurred on July 23rd day 205 of leap year 1940. There were frequent air frosts to end of June that year. Latest date accepted for this is July 31st then August 1st could be the earliest frost of the next cycle (same year).

Element 6 __ msg __ when available, this will be the difference of April 30 minus May 31 snow cover. e.g., --5 will indicate a loss of 5 cms. Zero indicates no change and any positive numbers indicate a net gain in snow cover in May. This element will track a vital precursor portion of the length of the arctic summer and melting period.

Element 7 __ 80J _ Indicates that the warmest month of 1940 was July with mean of 8.0. When it's June, the J will be replaced with jun. (The daily max in 1968 is the first case where June qualifies). August (A) will be the other month that might appear in this column. It is usually July.

Element 8 __ 172J _ Indicates that the warmest temperature of summer 1940 was 17.2 in July (same protocol for June or August as above).

Element 9 __ 215 __ First frost occurred August 2nd. This was an unusually cold day with a high of only 4.4 and a trace of snow. The range of this element will normally be mid-August to early September.

Element 10 __ 286 __ First snowfall in winter 1940-41 was October 12th. This is unusually late and looking at the September data one has to question whether some snowfall in September went unreported. This is not a general problem in the later records. When available, first snowfall from August 1st on, by date number. In non-leap years, August runs from 213 to 243 (214 to 244 in leap years). September runs from 244 to 273 (or 245 to 274 l.y.). This is the range that will usually be found here.

Element 11 __ 325 __ First -20 minimum occurred on November 20th in 1940. The range for this variable will be late October to early December. This is often a rough indicator of when ice will be sturdy enough for travel near shore at least.



Key Climate Indicators 1940 to 2016 -- part one 1940 to 1970

YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

1940 __ -296F_ -467F_ msg ___ 167 __ 205 _ msg _ 80J _ 172J _ 215 _ 286 _ 325

1941 __ -326J_ -433J_ msg ___ 147 __ 180 _ msg _105J _ 206J _ 217 _ 244 _ 293

1942 __ -366F_ -467F_ msg ___ 162 __ 179 _ msg _105J _ 211J _ 237 _ 252 _ 305^

1943 __ -337J_ -467J_ msg ___ msg$__ 173 _ msg _103A _ 194J _msg%_msg%_296

1944 __ -340F_ -433F_ msg ___ msg!__ 176 _ msg _ 72J _ 172J _ 239 _ 285 _ 300

1945 __ -315F_ -456J_ msg ___ no summer or Sept data for these stats ______ 293

1946 __ -372F_ -483F_ msg ___ 146 __ 190 _ msg _ 75J _ 194A _ 220 _ 256 _ 284

1947 __ -343J_ -467J_ msg ___ 135 to May 31 but no June to mid-Jan 1948 data __

1948 __ -349F_ -467F_ 13/121 _ 172 __ 175 __ 0 _ 110J _ 233J _ 240 _ 257 _ 287

1949 __ -380F_ -482F_ 41/151 _ 191*__ 190__+3 _ 82A _ 200A _ 237 _ 236 _ 287

1950 __ -391J_ -478F_ 46/140 _ 174 __ 177 __ 0 __ 63J _ 156J _ 227 _ 226 _ 293

1951 __ -372F_ -461F_ 45/110 _176#__ 178 __-5 _ 73A _ 228A _ 228 _ 254 _ 289

1952 __ -357F_ -450J_ 47/110 _ 130 __ 187 _ -18 _ 81J _ 200J _ 236 _ 244 _ 290

1953 __ -366J_ -461J_ 59/144 _ 175 __ 179 __-2 _ 77J _ 194A _ 230 _ 272 _ 293

1954 __ -338J_ -478F_ 38/120 _ 178 __ 179 _ -15 _110A_ 233A_ 246 _ 248 _ 289

1955 __ -382F_ -506F_ 42/147_ 171 __ 196 __ 0 __ 78J _ 233J _ 245 _ 251 _ 305

1956 __ -386F_ -456F _ 50/146 _ 203*__ 204 __-7 _ 94J _ 222J _ 237 _ 258 _ 285

1957 __ -371F_ -462F _ 46/150 _ 168 __ 179 __+2 _ 66J _ 189J _ 225 _ 258 _ 294

1958 __ -393F_ -483F _ 58/126 _ 159 __ 173 _ -12 _ 88A _ 167J _ 250 _ 270 _ 301

1959 __ -325F_ -433F _ 53/162 _ 174 __ 177 __+7 _ 61J _ 172J _ 238 _ 249 _ 290

1960 __ -348J_ -483J _ 25/152&_134 __ 175 _ -17 _ 92J _ 239J _ 250 _ 260 _ 290

1961 __ -377M_ -461M _20/143 _ 168 __ 176 __-5 _ 98J _ 211J _ 239 _ 251 _ 278

1962 __ -367F_ -483J _ 23/120 _ 152 __ 162 __ -8 _ 94J _ 228J _ 231 _ 247 _ 294

1963 __ -362M_ -456J _ 33/139 _157 __ 176 __ -5 _ 73J _ 189J _ 235 _ 243 _ 282

1964 __ -380J_ -483J _ 30/126 _ 195*__ 196 _ -15 _ 72A _ 211J _ 249 _ 255 _ 289

1965 __ -376F_ -467F _ 36/ 72 _ 158 __ 184 __ -7 _ 73J _ 167J _ 242 _ 243 _ 287

1966 __ -383J_ -494JF_ 20/135 _ 145 __ 176 _-17 _ 94J _ 189J _ 247 _ 260 _ 285

1967 __ -369F_ -467J _ 20/154 _ 150 __ 189 __+7 _ 65J _ 228J _ 225 _ 245 _ 296

1968 __ -351J_ -472JF_ 51/148 _ 191*__ 184 _-11a_ 63J _ 189jun 216a_215a_301

1969 __ -340J_ -439J _ 28/121 _ 177 __ 184 _ -18 _ 91J _ 228J _ 243 _ 261 _ 301

1970 __ -348J_ -439J _ 18/144 _ 172 __ 172 _ -15 _ 94J _ 200J _ 229 _ 244 _ 279

means _ -359 __-466 __37/134 _ 166 __ 182 __ -7 _ 84 __ 202 __ 235 _ 253 _ 293

freq ___ J 12 __ J 14 ________________________ Jun 0 _ Jun 1

_______ F 17 __F 16 ________________________ Jul 23 _ Jul 23

_______ M 2 __ M 1 _________________________Aug 6 _ Aug 5

(frequency is 0.5 when months tied).

(last snow avg date 162 if only pre-July cases used and 164 if all July cases but the 1956 outlier are used.)

1971 __ (note, data 1971 to 2017 will appear in the next post to keep this one manageable and so that the notes below are closer to the years that they reference.)

Notes:

$ _ no precip data June 1943, temps sometimes suitable for snow to 15th.

^ _ temp data msg 302-303, no -20 readings on days with data in October 1942

% _ all data msg Sept 1943, no air frosts or snow in August which was unusually warm

! _ no data May 1944, data but no snow June 1944, value 152 or lower

* all July snowfall notes

_ * In July 1949, a very cool month, 1.3 cm snow July 10 (after 0.3 cm 8th) can be considered the actual last snow as this did not happen after any substantial warmth, so when assessing trends will use 191 as value here. The date of the last pre-July snowfall was day 174 (June 23rd).

_ * In July 1956, 1.5 cm snow fell on July 21st during an otherwise rather warm month, and this was followed by an air frost, otherwise the latest frost had been June 16th (day 168). This is so far the only case of a true mid-summer outlier. Its value in terms of days is 203. The last snowfall before this had been on day 157 (June 5th in this leap year).

_ * In July 1964, 0.5 cm snow fell on July 13th, and there was little sustained warmth until after this event, so that the value 195 is probably appropriate. The last snowfall pre-July was on day 175 (June 23rd).

_ * In July 1968, 0.8 cm snow fell on July 9th, and the value 191 is probably appropriate. The last snowfall pre-July was on day 169 (June 17th).

# _ The last snow June 26 1951 was unusually heavy, 11.9 cm, None was reported as snow depth by June 30 despite ongoing chilly temperatures.

& _ A snow depth of 25 cm was reported from late December 1959 into early May 1960, not sure if this value is reliable or not (total snowfall was rather low so probably close, but the never-changing value over five months suggests a data recording problem or perhaps a frozen snow pack with small amounts being blown away from the site).

a _ There were several odd features to the end of winter and summer of 1968. The snow depth increased steadily from 36 cm to 52 cm during May, peaking on the 27th, then rapidly diminished to 25 cm. Then with late frosts and snowfalls noted under * there was no real summer at all, and unusually early snowfall and frost was noted in the first three days of August. After that no further snow fell until September 2nd (day 246). Temperatures from mid-September to mid-October were considerably above normal.

(continues next post)

(will edit for style and spacing later)

M.T. Cranium

note: 1970-71 is the first winter in this study to have either its coldest month or lowest daily minimum in the December of the winter (Dec 1970 in this case).

YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

1971 __ -346D_ -450D_ 25/110 _ 157 __ 173 _-10 _ 93J _ 194J _ 225b_ 225b_ 300

1972 __ -388F_ -483F_ 38/145 _ 178 __ 197 __+2 _ 59J _ 167A _ 228 _ 243 _ 280

1973 __ -345F_ -483F_ 28/132 _ 142 __ 171 _-20 _ 95A _ 228A _ 253 _ 272 _ 295

1974 __ -358F_ -472F_ 25/128 _ 157 __ 177 _-10 _ 94J _ 239J _ 226 _ 226 _ 278

1975 __ -369J_ -494J_ 20/-59c _ 146 __ 155 __-7 _ 88A _ 211A_ 237 _ 243 _ 285

1976 __ -345F_ -467JM_25/125_ 170 __ 190 _-20 _ 83J _ 194J _ 221 _ 255 _ 289

1977 __ -357F_ -483F_ 35/135 _ 147 __ 168 _-23 _ 83J _ 189jun_246 _ 255 _ 290

1978 __ -307M_ -436F_19/147 _ 169 __ 193 __-2 _ 45J d_137J d_223 _ 241 _ 281

1979 __ -382F_ -495F_ 31/133 _ 159 __ 180 _-19 _ 71J _ 174J _ 227 _ 229 _ 279

1980 __ -343J_ -438J_ 51/131 _ 167 __ 168 _-28e_ 75A_ 196A_ 232 _ 262 _ 297



(1940 or available data to 1980, means for decade and cumulative through 1980)

decade 1971-80 means

mean _ -354 _-470__30/113* _ 159 _ 177 __-14 _ 79 __ 193 __ 232 _ 245 _ 287

(41yr) _ -358 _-467 __35/128*_ 164 _ 181 __ -9 __83 __ 200 __ 234 _ 251 _ 292

cumulative frequency 1940-80

______ D 1 __ D 1

______ J 14 __ J 16,5_____________________ Jun 0 _ Jun 2

______ F 23 __F 22 ______________________ Jul 30 _ Jul 28

______ M 3 __ M 1.5______________________ Aug 9 _ Aug 9

* the earlier average for maximum snow depth is almost all due to the one anomalous case (see note c) and would have been 130 using the secondary maximum. The cumulative would have been 131. This anomalous data point reduces the overall (77-yr) average by 2 days. So it depends on whether you want to study the climatology of snowfall (accept all dates within the season) or the peak before melt begins (accept dates after March 1st). This anomaly was not repeated later in the series,



Notes:

b _ The early snow and air frost of -0.6 C (Aug 13, 1971) were accompanied by WNW winds gusting 109 km/hr.

c _ The winter of 1974-75 had very light snowfall and its greatest depth came on Nov 2, 1974. (20 cm). This is the first winter in the study period that had its maximum before March let alone in the previous year's portion. The date number -59 is for the average since day 1 is Jan 1, day 0 is Dec 31, day -30 is Dec 1 and day -60 is Nov 1st. The maximum depth attained in the spring months was 18 cm on April 27th (after dropping as low as 13 cm in Jan to Mar. This snow-devoid winter was then followed by a record warm June (7.0 C). During this month of mostly southeast winds, a strong NW wind blew for two days (21st-22nd) gusting near 100 km/hr both days. After quite a warm summer for this location, a wintry storm developed September 8-9 with 6.3 cm snow and NE winds gusting to 116 km/hr.

d _ These were the lowest values for warmest month and day in the series. This suggests that in a colder climate interval than the 20th century, it would be conceivable to find summers where snow never melted on Victoria Island (of course this would be the case before a glacial period but possibly also in inter-glacial cold episodes -- not enough is really known to say whether those might be most likely in hemispheric coolings like the Maunder or LIA, or independent localized phenomena of the arctic islands -- it should be made clear that no such outcome is implied in 1978 but that would be a summer when it might be possible to find remnant snow fields in central Victoria Island perhaps). Basically the warmer spells were very muted and confined to late July and early August of 1978. However, September stayed rather mild and there was little snow on the ground even during colder weather by mid-October.

e _ This snow loss from April 30 to May 31 was larger than all others before it, but left 20 cms on the ground which is well above most other years. The circulation during the second half of May was mainly easterly.

ANALYSIS

During the 1971-80 decade, there was little substantial change to winter's coldest temperatures, and summers were actually somewhat cooler than the 1940-70 period (where two years are missing, those could have been cooler and made the difference less apparent). Other variables shifted slightly as the means demonstrate, but the main item of interest was the rather variable intrusion of an early AGW signal possibly in 1975 after a very snow-deprived winter, which led to a much different summer than most others both in duration and storminess at each end. There are perhaps arguments available here for this decade being either largely a continuation, or the first signs of a shift in climate.

So now it's on to the 1981-90 decade to see what trends emerge there.


YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

1981 __ -313F_ -445F_ 21/ 99 _ 154 __ 167 _-14 _ 78J _ 192A _ 240 _ 222 _ 301

1982 __ -352F_ -436F_ 30/ 94 _ 174 __ 177 _-12 _ 74J _ 206Jj _ 229 _ 233 _ 291

1983 __ -374F_ -446J_ 54/119 _ 166 __ 168 __-8 _ 90J _ 198J _ 230 _ 260 _ 286

1984 __ -349J_ -468F_ 47/131 _ 109^__169 _-12 _ 92J _ 207J _ 233 _ 250 _ 302

1985 __ -365F_ -456F_ 44/128 _ 164 __ 211$_-12 _ 64J _188jun_232 _ 232_ 294

1986 __ -352J_ -449F_ 37/149 _ 163 __ 173 _+10 _ 71J _ 224J _ 233 _ 235 _ 280

1987 __ -330J_ -441F_ 40/113 _ 176 __ 176 __-5 _ 76J _ 175J _ 242 _ 217z_ 288

1988 __ -352J_ -452J_ 39/144 _ 170 __ 173 __-3 _ 89J _ 218jun_238 _ 252 _ 294

1989 __ -313F_ -445F_ 43/135 _ 166 __ 168 __-3 _ 98J _ 269J _ 252 _ 259 _ 289

1990 __ -382F_ -465F_ 44/143 _ 165 __ 172 _-11 _ 85J _ 228J _ 250 _ 247 _ 289



(1940 or available data to 1990, means for decade and cumulative through 1990)

decade mean for 1981-90

______ -348 __-450__40/126 _ 161 _ 175 __-7 _ 82 __ 211 __ 238 _ 241 _ 291

(51yr) _-356 __-463 __37/127 _ 163 _ 180 __-8 _ 82 __ 202 __ 235 _ 249 _ 292

cumulative frequency 1940-90

______ D 1 __ D 1

______J 18 __ J 18.5_____________________ Jun 0 _ Jun 4.5

______F 29 __F 30 ______________________ Jul 40 _ Jul 34.5

______M 3 __ M 1.5______________________ Aug 9 _ Aug 10



Notes:

1982 daily max of 20.6 in both June and July.

^ _ 1984 last spring snowfall April 19th, snow depths varied after this by over 20 cm so this needs further investigation, no measurable snow in May for first time in this set of data (since 1940).

$ _ This frost on July 30, 1985 (-1.6 C) was perhaps the most isolated in the record in terms of taking place in the warmest portion of summer. The last frost before it was on June 22nd (day 173). Almost all other July frosts are in the first half of the month.

z _ On August 5, 1987, a rather unusual early snowfall of 2.6 cm, no air frost (min same day 0.5 C).

1988 had very mild weather (above freezing) in late September lasting into the first part of October without frosts. Normally it is around -8 to -15 at this point in the early winter.

1989 had a very warm summer, July at 9.8 and August at 8.8 with the maximum of 26.9 the highest since 1930.



ANALYSIS (1981-90):

There were slight increases in the temperature data mostly based on the onset of considerably warmer conditions in 1988 to 1990, but little associated change in the dates of first or last frosts and snowfalls, or the onset of -20 C readings. Perhaps the biggest change was increased snowfall evident after 1982. This seemed to return the snow climatology to the heavier amounts often seen in the first part of this study.


YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

1991 __ -354J_ -449M_ 47/135 _ 156 __ 166 __+1 _ 83J _ 261A_ 239 _ 237 _ 287

1992 __ -348J_ -423F_ 47/144 _ 163 __ 187 ___ 0 _ 75J _ 212J _ 239 _ 266 _ 294

1993 __ -335F_ -476F_ 59/129 _ 179 __ 166 __-5 _ 94J _ 218J _ 221 _ 239 _ 299

1994 __ -318J_ -414M_ 35/113 _ 162 __176 _-24 _105J _ 222J _ 242 _ 242 _ 311

1995 __ -322F_ -471M_ 46/127 _ 188*__169 ___0 _ 80J _207A _ 239 _ 240_ 285

1996 __ -340DJ -481J_ 49/129 _ 163 __ 173 _-35 _123J _ 233jun_237 _233 _ 295

1997 __ -322F_ -433F_ 26/136 _ 184*__ 180 __-8 _ 96J _ 223J _ 241 _ 236 _ 299

1998 __ -353J_ -439F_ 39/123 _ 151 __ 166 _-11 _107J _ 246J _ 260 _ 248 _ 304

1999 __ -319J_ -415F_ 36/142 _ 161 __ 183 __+3 _ 71A _ 180J _ 243 _ 243 _ 289

2000 __ -312F_ -429J_ 33/152 _ 154 __ 167 __+3 _109J _ 252J _ 240 _ 250 _ 290



(1940 or available data to 2000, means for decade and cumulative through 2000)

decade mean for 1981-90 (top row)

mean _ -332 _-443__42/133 _ 166 _ 173 __-8 __ 94 __ 225 __ 240 _ 243 _ 295

(61yr) _ -351 _-460 __34/127*_ 164 _ 177 __-9 _ 84 __ 206 __ 236 _ 248 _ 292

mean of 1940 to 2000 (second row)

would be day 129 if anomalous early date in 1974-75 not used.



cumulative frequencies for temperature extremes (1940-2000):

_______ D 1.5 __ D 1

_______ J 23.5_ J 20.5_______________________ Jun 0 _ Jun 5.5

_______ F 33 __F 35 ________________________ Jul 49 _ Jul 41.5

_______ M 3 __ M 4.5________________________Aug 10 _ Aug 12



Notes:

* _ July 1995 had 0.2 cm snow on July 7th. (day 188) The pre-July latest was quite early, day 144 (May 24).

* _ July 1997 had 0.2 cm snow on July 3rd. (day 184). The pre-July latest was day 175 (June 24th).

Winter 1995-96, Dec and Jan tied for coldest month.

Summer 1996 had an exceptional warm spell June 22 to July 8 and a minor resurgence in late July. After rather cool weather in early August, there was 19 cm of snow August 20-21. Most of this apparently melted within two days.

Summer 1998 was very warm, July at 10.7 and August at 9.6 C.



ANALYSIS (1991-2000):

Significant warming can be seen in the winter and summer extreme elements which ran about 2 deg warmer than previous decades. Summer warmth is a more expected condition (since 1988) and no year in this decade had a summer "no show" like other decades managed once or twice. At the same time, other elements did not respond in the same way, although the first -20 of winter came a few days later. The heavier snow period seemed to taper back to more long-term average amounts after about 1996.






(decade of 2001-2010)


YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

2001 __ -322J_ -432J_ 58/150 _ 176 __ 172 __+8 _108J _ 237J _ 241 _ 260 _ 296

2002 __ -348F_ -425F_ 27/154 _ 169 __ 172 __ -1 _ 82J _ 206J _ 247 _ 266 _ 299

2003 __ -345F_ -464F_ 37/115 _ 175 __ 176 __-2 _ 93J _ 207J _ 255 _ 260 _ 293

2004 __ -350F_ -448F_ 36/142 _ 183*__170 __ -3 _ 68J _ 205J _ 249 _ 249 _ 286

2005 __ -349F_ -439NJ_38/115 _ 167__168 _-27 _ 77A _ 173J _ 242 _ 257_ 288

2006 __ -295J_ -431M_ 39/ 90 _ 148 __ 173 _-22 _ 98A_ 233A _ 248 _ 269 _ 304

2007 __-317M_ -441M_ 35/117 _169 __ 172 __+2 _119J _ 244J _ 237 _ 250 _ 298

2008 __ -357F_ -454M_ 43/132 _ 170 __ 169 _-15 _ 95J _ 226J _ 238 _ 252 _ 305

2009 __ -327M_ -441M_ 49/107 _ 192*__192 __+3 _ 81A _ 187J _ 252 _ 268 _ 297

2010 __ -280F_ -430F_ 33/134 _ 169 __ 174 __-2 _102J _ 222A_ 251 _ 264 _ 307



(1940 or available data to 2010, means for decade and cumulative through 2010)

decade 2001-10

mean _ -329 _-440__40/126 _ 169 __ 174 __-6 _ 92 __ 214 __ 246 _ 260 _ 297

(71yr) _ -349 _-457 _37/128**_ 165 __ 178 __-8 _ 86 __ 207 __ 237 _ 249 _ 293

** would be day 130 not using anomalous early case in 1974-75.

cumulative frequencies for temperature extremes:

_______ N _ 0 __ N 0.5

_______ D 1.5 __ D 1

_______ J 25.5_ J 22.0_______________________ Jun 0 _ Jun 5.5

_______ F 39 __F 39 ________________________ Jul 55 _ Jul 49.5

_______ M 5 __ M 8.5________________________Aug 14 _ Aug 14

Notes:

2003: Jan unusual mild incursion, -8 C on 6th, trace of (freezing) rain

* _ 1.2 cm snow on July 1st, 2004 (day 183) -- pre-July date was 173.

* _ 2.6 cm snow on July 11th, 2009 (day 192) -- pre-July date was 172.

winter 2004-05 had coldest minimum shared by Nov and Jan, only instance where Nov set or shared this mark. Snow cover had developed more rapidly than in many other autumns in 2004. It was 22 cms on Nov 28th when the minimum (-43.9) was set.

2007: This was the autumn with the large open water anomaly north of eastern Siberia (ice free to 86 N well into the autumn) -- after a very warm July, weather at YCB was fairly normal from late August into October but snow appears to have been somewhat more frequent in mid-October, perhaps a feedback from this open water source although surface wind directions were reported as north to northeast much of the time this snow was falling. Snow cover reached 22 cms end of October which is more than most years. During eventual freeze-up of this anomaly, the open water energy dissipation may have been the cause of strong NW winds Dec 4-8, but no new snow was associated.

2010: Interesting to note, given the unusually cold weather in Britain after mid-November, the conditions were unusually mild all through the autumn at YCB. Record highs were set around Dec 19-20 (about -3 C). However, snow continued to increase gradually to an unusual depth of 40 cms by Dec 26th.



ANALYSIS (2001-2010):

The temperature signals remained close to the slight warming seen in the previous decade although summers backed off slightly from that peak, while winters remained about the same. It was noteworthy that the coldest time of the winter was more frequently March than in the past. The snow cover and frost statistics were similar in the spring but more representative of a warming climate in the early autumn, all indicators there shifted about five days later. The long-term averages now appear slightly different than they did in 1980. These are the net changes since 1980:



(41yr) _ -358 _-467 __35/128 _ 165 _ 181 __ -9 _ 83 __ 200 __ 234 _ 251 _ 292

(71yr) _ -349 _-457 __37/128 _ 165 _ 178 __ -8 _ 86 __ 207 __ 237 _ 249 _ 293



As the period 1981-2010 is 3/4 as long as the base period 1940-80, or about equal for the snow depth portion, it can be surmised that the changes in the recent 30 year averages will be a bit more than twice as large as the shift in the cumulative record. But in any case, the cumulative averages have shifted by these amounts:

SHIFT _ +0.9 _ +1.0 _ +2cm, 0d _ 0d _ -3d _ +1cm _ +0.3 _ +0.7 _ +3d _ -2d _ +1d

These shifts are marginally significant to borderline moderately significant for the winter temperature data. Snow cover changes have been periodic rather than showing any real trend. The snow-free period (including about 10% of years with a July snowfall) has not really shifted very much and statistically has decreased by 2 days (from 165-251 or 86d to 165-249 or 84d) while the frost free period has increased by 2 days. Part of the uncertainty in this is that recording changed from whole degrees F to tenth-degree C which eliminates some of the potential frost candidates (0.1 to 0.3 C could have been reported as 32 F). This may actually explain most of the variation in this statistic since a correlated stat, change in snow cover April 30 to May 31, shows a slight trend towards a colder signal (less reduction). Also, with some marginal frosts removed, the relative timing of first snow and first frost has shifted. This is a rather complex mixing of a few cases of large separations with cases that would be assessed the same way due to a more pronounced first frost case.

Really, as we now go to the last seven winters and six summers to complete this study, the indications of a large shift in climate at YCB are faint overall. It is more a case of a few anecdotal oddities such as a couple of mild spells in mid-winter and the more frequent warm spells in mid-summer, as to the basic climate, it seems fairly robust.





(2011 to 2019)


YEAR __ 01 ___ 02 ___ 03 ____ 04 ___ 05 __ 06 __ 07 __ 08 ___ 09 ___ 10 __ 11

2011 __ -312J_ -451M_ 49/130 _ 179 __ 174 __+1 _109J _ 200J _ 244 _ 267 _ 301

2012 __ -320J_ -426J_ 43/149 _ 156 __ 171 __ +7 _108J _ 198A _ 254 _ 227 _ 297

2013 __ -361F_ -427F_ 26/102 _ 139 __ 170 __-9 _ 80J _ 214A _ 235 _ 235 _ 311

2014 __ -318J_ -426J_ 30/148 _ 160 __ 172 __ -6 _ 84J _ 205J _ 250 _ 247 _ 295

2015 __ -317F_ -412F_ 35/121 _ 170 __172 _ -21 _ 95J _ 203A_ 247 _ 268 _ 294

2016 __ -319F_ -385D_ 26/144 _ 153 __164 __ -1 _103J_ 248J _ 250 _ 250 _ 293

2017 __ -309F_ -459M_ 41/105 _ 148 __172 __-32 _ 97J_ 224J _ 241 _ 251 _ 296

2018 __ -325F_ -449F_ 31/135 _ 150 __188 __ +4 _ 83J_ 184J _ 233 _ 233 _ 288

2019 __ -331J _ -416J_ 51/134 _ 162 __164 __--2 _ 84J_ 219A _ 243 _ 280*_ 299

* With considerable missing data mid-Sept to Oct 7, this is the last possible date for first

reported snow on the ground on Oct 8 (d281). It could have fallen at some point between

days 259 and 280. Will be attempting to get a more accurate number for this data point

from weather maps or other secondary data. This was a much longer data outage than

is usually the case at YCB.



(1940 or available data to 2019, means for decade and cumulative through 2019)

period 2011-19

mean _ -324 _-428__37/130 _ 157 __ 172 __-7 _ 94 __ 211 __ 244 _ 251 _ 297

(80yr) _ -346 _-456 _37/128 _ 164 __ 177 __-8 _ 87 __ 208 __ 238 _ 250 _ 293

cumulative frequencies for temperature extremes:

Coldest month __ day ________________ Warmest month __ day

_______ N _ 0 __ N 0.5

_______ D 1.5 __ D 2

_______ J 29.5_ J 25.0_______________________ Jun 0 _ Jun 5.5

_______ F 44 __F 42 ________________________ Jul 64 _ Jul 54.5

_______ M 5 __M 10.5________________________Aug 14 _ Aug 18



ANALYSIS (2011 to 2019)

Most of the data continue the same trends, a slight warming of winter temperature extremes as well as summer, although the peak of warmth appears to have been back around 1998, trend is fairly flat since then. Snowfall has been somewhat lower in this past nine year interval.

(as posted in March 2017)

I will be looking over the data in graphical format after I have a chance to input into an excel file. More comments will be posted then.

I would say in general that you can see the effects of a warming trend but perhaps the impacts are less massive than some might speculate. The most changed part of the year seems to be late August and early September, winter as we would recognize it in our southerly latitudes now sets in a bit less quickly and there seems to be (in most years) a longer pause between the warmth of summer (which often fades after August 10th) and any real winter conditions in terms of snow cover or days staying below freezing. The pause interval seems to involve weeks of near-freezing temperatures, small amounts of rain and snow mixed, and from the looks of other data, northerly flow but not very strong.

The snow data and temperatures for May and June convince me that if snow cover was reduced in general, the summers would start earlier and get quite warm by mid-June. As soon as snow is removed, temperatures often respond by rising 5 to 10 degrees, but one would have to survey the wider landscape around YCB to get a better idea of how much snow persists in higher terrain nearby. I did notice several occasions when snow apparently drifted into the observation site because snow depth would increase despite a lack of reported snowfall. The wind direction most associated with this phenomenon was easterly. I also saw some examples of where snow may have been blown away from the measurement site by westerly winds.

(note added: the study has now been put onto an excel file and all data adjusted after recalculations, just minor second decimal issues)

Also, the last snowfall dates have been adjusted so that July data now appear in that column and not the pre-July dates which are now found in the notes. This basically shifts the average back about four days overall (from 161 to 165).

M.T. Cranium

Resolute is located in the central arctic islands, on the southern shoreline of Cornwallis Island located to the west of larger Devon Island and northwest of Baffin Island (north of Somerset Island), and is roughly 700 kms northeast of YCB. It is located at 74.7 deg north, 95.0 deg west. The North Magnetic Pole was very close to this location around the 1950s and has since drifted almost 1500 kms away to the west-northwest. Weather records have been almost continuously maintained there since October 1st,19 1947. This gives us almost total overlap with the YCB series, especially for snowfall since YCB had several gaps between 1940 and 1947 in that element. So I will be updating this thread with a similar analysis of trends at Resolute.

The climate there is somewhat more arctic in characteristics than Cambridge Bay. There is almost no influence from the southwest of warmer air masses in the summer; if it warms up at all at Resolute (and in many summers, it does not get much above 10 deg at best), this is a gradual heating of an in situ air mass over the east-central arctic and usually well correlated with anomalous warmth in Baffin Island and even Greenland. Instead of the faint appearance of a frost and snow free period, Resolute sees a greater mixing of summer precipitation to reach about a 3:1 preponderance of rain over snow, but there is no real snow-free season as such, although in warmer years there can be (the data will show this tendency).

Winters at Resolute differ from Cambridge Bay mainly in the greater number of windy days and the more frequent intervals when milder air intrudes from the east to southeast. Strong low pressure systems often move west in the winter half year around the latitude of southern Baffin Island into northern Hudson Bay or the Foxe Basin. Temperatures there can rise as high as -5 to +2 C but Resolute tends to get a more modified warming to -15 or -10 C on most occasions, significant snow, and very rarely freezing drizzle or rain. Sometimes these storms produce winds of 80 km/hr sustained and 120 km/hr in gusts, and on one occasion in November 1965, wind gusts to 158 km/hr.

However, these periods are not guaranteed to occur every winter, and when they don't, the climate becomes very similar to Cambridge Bay, with long settled periods of -30 to -40 C chill. The season of darkness is also a bit longer, from early November to early February and the days of continuous daylight run from late April to the first few days of August. Despite this, the sun dips low enough each "summer" day to allow for a diurnal range to take place, albeit often less than five degrees.

The following data take us from 1948 to 1970. I will then add later decades as I did with Cambridge Bay. Each time I calculate averages for the same elements used at Cambridge Bay, I will show the differences and we can keep track of how the station to station differences are changing over time, if in fact they do change. The one thing that we won't require in this study will be notes on July dates for end of snowfall seasons -- it will be quite frequently the case that the seasons end and then start up again fairly close to the arbitrary boundary of July 31st - August 1st. The elements listed below (a reminder in summary form) are:

01 is coldest month (no neg signs, 0.1 deg C) and 02 is the lowest minimum of the winter. Letters indicate months.

03 is the greatest snow depth of the winter season. I will make a change here to show (a) the greatest snow depth with date and (b) the greatest snow depth after March 1st, thinking that there may be more than the one exception that we found with Cambridge Bay. Only 3 (b) will be useful in correlating with YCB. As with YCB it was necessary to estimate actual dates from 1948 to until daily snow depth was reported, before that it is just end of month snow depths from which one could derive daily estimates. In general, I don't think there is as much drifting of snow into this location from other parts of the landscape as it is a more rocky, hilly location and also the snow tends to be wetter and exposed to freeze-thaw cycles that might not promote much drifting (not to say there would not be prodigious drifting of snow away from the airport and townsite on the more exposed parts of the island and other nearby islands).

(where no 3a entry, the 3b entry is the seasonal snow depth max).

(zero or negative dates in 3a refer to previous year 0 being Dec 31, -30 being Dec 1, -60 Nov 1 etc).

04 and 05 are last snowfall and last frost dates with July 31st the end point.

06 shows the change in snow depth (in cms) during May, from April 30 to May 31.

07 and 08 show the summer extremes, monthly and daily, with months of occurrence.

09 and 10 show the first frost and snowfall dates from August 1st on, and 11 shows the date of the first -20 daily min.

YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11

1947 ____ no data except last element __________________________________ 277 (or in msg Sep)

1948 __ 377F_ 483M_ ---- _ 53/152 _ 169 _ 205 _ +33 _ 51J _ 139J _ 218 _ 227 _ 290

1949 __ 369F_ 467F_ ---- _ 35/153^_ 203 _ 210 __ 0^ _ 45J _ 150A _ 220 _ 236 _ 276

1950 __ 369J_ 467F_ ---- _ 32/160 _ 170 _ 185 __ +2 _ 45J _ 122J _ 215 _ 222 _ 277

1951 __ 368F_ 467F_ ---- _ 23/152 _ 212 _ 212 __ +5 _ 48J _ 150J _ 213 _ 230 _ 285

1952 __ 337J_ 472J_ ---- _ 26/124 _ 205 _ 212 _ --23 _ 45J _ 156J _ 222 _ 226 _ 281

1953 __ 344J_467FM_ -- _ 34/122 _ 172 _ 211 __ --8 _ 35J _ 117J _ 213 _ 254 _ 282

1954 __ 338F_ 461J_ ---- _ 45/137 _ 167 _ 203 __ +5 _ 49J _ 161J _ 228 _ 259 _ 289

1955 __ 382F_ 494F_ ---- _ 38/130 _ 203 _ 212 __ --2 _ 28J __ 94J _ 214 _ 213 _ 293

1956 __ 364M_ 517M_--- _ 55/113 _ 206 _ 210 __ --2 _ 40J _ 144J _ 224 _ 223 _ 280

1957 __ 363J_ 456F_ ---- _ 33/138 _ 203 _ 207 __ --5 _ 55J _ 150J _ 215 _ 221 _ 286

1958 __ 354F_ 456F_ -a- _ 25/124 _ 154 _ 200 ___ 0 _ 60A _ 139A _ 236 _ 250 _ 283

1959 __ 347F_ 467J_ -b- __ 15/ 72 _160 _ 205 __ --3 _ 45J _ 111 J _ 213 _ 222 _ 274

1960 __ 341M_ 433J_ ---- _ 30/116 _ 160 _ 207 __ --2 _ 54J _ 150J _ 227 _ 245 _ 286

1961 __ 373M_ 467M_---- _ 56/123 _ 198 _ 211 _ --10 _ 40J _ 143J _ 220 _ 232 _ 284

1962 __ 352F_ 456J_ ---- _ 38/153 _ 182 _ 182 ___ 0 _ 76J _ 183J _ 223 _ 232 _ 281

1963 __ 346M_ 428M_ --- _ 36/156 _ 181 _ 211 __ +3 _ 44J _ 139J _ 214 _ 227 _ 281

1964 __ 347F_ 467J _ ---- _ 46/153 _ 213 _ 213 _ +10 _ 22A _ 89JA _ 214 _ 214 _ 277

1965 __ 324J_ 422F_ ---- _ 25/150 _ 211 _ 212 __ +3 _ 27J _ 133 J _ 213 _ 233 _ 272

1966 __ 375J_ 522J_ ---- _ 33/165 _ 200 _ 207 __ --3 _ 37J _ 122 J _ 223 _ 230 _ 283

1967 __ 364F_ 468F_ ---- _ 30/150 _ 196 _ 208 __ +5 _ 27J _ 100 J _ 213 _ 220 _ 289

1968 __360F_472M_66/-61#.53/151_ 182 _211 _ +18 _ 45J _ 122J _ 217 _ 214 _ 300

1969 __ 313M_414M_ ---- _ 38/ 76 _ 199 _ 210 __ +3 _ 35A _ 128A _ 216 _ 243 _ 288

1970 _ 316JF_467JF_ ---- _ 41/119 _ 208 _ 208 _--10 _ 48J _ 156 J _ 214 _ 226 _ 278



means _ 353 _ 465 _37/125_37/134_ 189 _ 207 _ +1 _ 44 __ 135 ___ 218 _ 230 _ 283

__YCB_ 366 _ 468 _ -- -- __ 37/134 _ 168 _ 181 _ -7 _ 82 __ 205 ___ 237 _ 250 _ 291



Notes:

^ The snow on ground at end of March and May 1949 reported as 33 cms, April zero, seems like a data omission zero rather than a measured zero as April was generally cold and dry. In any case, the maximum snow depth might have been marginally higher at any point in the three months but likely increased slightly from 4.6 cms that fell June 1-2 in rather mild conditions, so added 2 cms there (likely melting after that), and the difference is set at zero rather than the +33 that the raw data would indicate. No wind data for this early in the record to eliminate snow drifting as a potential reason.

___ 1953 and 1954 had no measurable snow in July or August. Nor did 1958 or 1960.

___ 1955 had an exceptionally cold summer, mean of --0.7 in June, 2.8 in July, 2.0 in August. (mean 1.4 C).5 cms of snow fell in July and 15 cms in August. This followed one of the colder winters (February was decidedly cold).

a __ In winter 1957-58, an early sub-max was 23 cms on Dec 2 1957. Amounts were generally 18-23 cms from then to the peak of 25 cms in early May.

___ 1958 had a rather warm summer, July averaged 5.9 and August 6.0. There was no measurable snow after June 3.

b __ In winter 1958-59, an early sub-max was 13 cms on 3rd of October 1958, amounts were much less than normal all winter peaking at only 15 cms in mid-March.

___ 1961 had heavy snow pack built up in Nov-Dec 1960 that stayed in the 40-55 cm range and had not totally melted until July 3rd.

___ 1962 had a very warm July, it was particularly warm 15th to 23rd and hit 18.3 (65F) on 18th and 21st.

___ 1964 had an even colder summer than 1955, means for the three months were -1.1, 1.2 and 2.2 (overall mean of only 0.8). The highest reading was 8.9 C (48 F). Frost and snow were frequent even at the end of July, into early August so there was no real snow or frost free season.

___ 1965 also had a cold summer, means were -2.8, 2.7 and 2.1, overall just 0.7 C. Snow was frequent at the end of July but absent for most of August.

___ There was also a severe wind storm on Nov 19-20 of 1965, many hours reporting sustained winds in the 100-140 km/hr range (easterly) and a peak gust of 158 km/hr on the 20th. No snow fell but there was blowing snow reported. Temperatures peaked at -5 C, about 20 above normal.

___ 1967 brought the third out of four consecutive very cool summers, the three-month mean was 0.9 C and there was a total of 32 cms of snow in July and August.

# _ 1967-68 max snow first peak on Oct 31, 1967 is either due to drifting in strong east winds, or a faulty data entry. The depths on Oct. 30 and Nov. 1 were 25 and 28 cms and no other days had any amounts over 30 cms in these two months. The data point is accepted for now because of the possibility of drifting snow causing the depth (and then drifting out of the range of the observer). The more reliable seasonal peak comes at the more normal time (53 cms on May 30, 1968),



ANALYSIS (1948 to 1970)

This period will give us a baseline for future comparisons of YRB and YCB. In this period (only the same years are used for YCB) the winter extremes are very similar, mean of coldest month at YRB on average 1.3 C warmer, mean of coldest daily minimum just 0.3 higher. The distribution of months is similar, for this interval with a slight shift to a later profile for YRB. The coldest month at YRB was in January 6.5 times, February 11.5 times, and March 5 times. In the same winters, the distribution at YCB was 9, 12 and 2 cases. The comparison for coldest daily minimum is YRB with YCB in brackets 7.5 (10), 9 (12), 6.5 (1). Here again, YRB shifts somewhat later into the winter season on average, but both locations hit their minimum in February more often than January or March.

There was fairly good correlation year to year in winter temperatures but winters of 1963-64 and 1964-65 ran notably colder at YCB.

The deepest snow pack (when spring cases are compared) is identical, on average 37 cms in mid-May (day 134). The pack increased by 1 cm on average during May, compared to a loss of 7 cm at YCB. The last snow and last frost at YRB were 21 and 24 days later than at YCB, and pushed into July.

The summers at YCB were of course considerably warmer. The warmest month averaged 3.8 C deg lower at YRB and the summer maximum averaged 7.0 deg lower. The distribution at YRB is more July-centric than for YCB which occasionally ventures into June and August more often. Only 3 summers had their warmest month in August (none in June) and only four had their warmest day in August, out of the 23 years in this data set.

There was not as good correlation in summer temperatures from YCB to YRB. From about 1957 to 1959, YRB ran only 1-2 deg colder than YCB. YRB ran much colder in intervals 1953-56 and 1964-67. There may be a solar cycle cause and effect hypothesis to examine once we have all data available.

The onset of autumn-early winter at YRB is usually in August and comes 19-20 days earlier for first frost then first snow, compared with YCB. The first -20 minimum comes just seven days earlier; one case fell in September.

As we move on to later decades, we'll see if YRB responds to the same trends as YCB or whether there are any significant differences in the contrasts between the two liocations.

(1971 to 1980)

YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11


1971 __ 327F_ 433J_ ---- _ 48/153 _ 212*_ 212 _ +12 _ 58J _ 133J _ 213 _ 219 _ 287

1972 __ 376F_ 489F_ ---- _ 33/160 _ 176 _ 213 __ +3 _ 28J _ 100A _ 214 _ 224 _ 275

1973 __ 352F_ 456M_ --- _ 25/148 _ 208 _ 209 __ --2 _ 36J _ 133JA_ 223 _ 224 _ 295^

1974 __ 337J_ 433F_ ---- _ 79/167 _ 203 _ 212 _ +21 _ 32J _ 128A _ 216 _ 223 _ 283

1975 __ 370J_ 478J_ ---- _ 38/130 _ 194 _ 212 _--13 _ 28jun_122jun_213_ 216 _ 268

1976 __ 339F_ 456J_---- _ 48/145 _ 194 _ 207 ___ --3 _ 36J _ 167J _ 214 _ 214 _ 282

1977 __ 367F_ 446F_ 18/0_18/150 _ 148 _ 211 __ --5 _ 53J _ 142J _ 220 _ 243 _ 281

1978 __ 327M_427D_32/-77_38/150_180 _ 194 __ +7_ 49J _ 129J _ 215 _ 217 _ 277

1979 __ 409F_ 520F_ ---- _ 30/151 _ 195 _ 197 __ +5 _ 38J _ 141 J _ 216 _ 222 _ 291

1980 __ 306D_ 430D_ 25/31_28/165_ 204 _ 204__ +4 _ 43J _ 124A _ 224 _ 224 _ 275



means _ 351 _ 457 __ xxxx _ 39/152 _ 191 _ 207 __ +3 _ 40 __ 132 __ 217 _ 223 _ 281

_YCB __ 354 _ 470 __ xxxx _ 30/130 _ 159 _ 177 _ --14 _ 79 __ 193 __ 232 _ 245 _ 287

cumulative 1948 to 1980

means _ 353 _ 462 __ xxxx _ 37/140 _ 190 _ 207 __ +1 _ 42 __ 134 __ 218 _ 228 _ 283

_YCB __ 362 _ 469 __ xxxx _ 35/133 _ 166 _ 180 __ --9 _ 81 __ 201 __ 235 _ 248 _ 290



Notes:

*__ 1971 last snow on July 31st came after a snow-free period June 12th to July 30th, so perhaps in this case the July 31st snow should be seen as the first snow of the next winter, and the data point is really day 162. Can't bend the rules though. The snow-free period was generally a bit warmer than normal too.

__ 1972 had a very cold summer, the mean of the three months was only 0.2 C (June was -3.2, July 2.8 and August 0.9). Despite this, no measurable snow fell from June 25th to August 10th.

^__ October 1973 was unusually mild to about the 20th, temperatures were barely below freezing; snowfall while frequent was not heavy. However, snow depths continued to mount up slowly all through the last three months of the year to reach 46 cms at New Years (more than usual). This depth was maintained to April 1974 then further accumulation in May peaked with 79 cms on the ground June 7th to 16th. This all melted by July 7th. The summer averaged quite cold (0.5 C) but mostly because June was very cold at -4.2, July was 3.2 and August 2.4 C.

__ Summer came and went very early in 1975. This was the first year in the series with either a warmest month or day in June. The only real warmth came around the last week of June, July turned quite chilly and August was colder yet. The first -20 C minimum was the earliest in the series (Sept 25th).

__ Jan 1977, when temperatures were far below normal in the Great Lakes and northeast U.S., was a very mild winter month for YRB. The mean was -23.8, about 8 above average. The maximum on January 11th was -0.8 C with light snow and a moderate east wind. This was probably 20 degrees higher than most winter months manage to produce. The period 10th to 16th had daily maxima continuously above -10 C and the month had only 10 cms snow cover throughout. Altogether, this was a singularity of some significance in the weather records for the location. Note also, there was one snowfall max of 18 cms on Dec 31 1976 (day 0) and another on May 30 (day 150). The December 31 max was sustained through a large part of Nov-Dec. In between, snow cover almost disappeared around late January (9 cms).

__ No measurable snow fell in June 1977 (or in July). This was the earliest date for the last snow (May 28th).

__ (3a) 1977-78 winter, Oct 15 (date -77) had a secondary max of 32 cms, snow depths thereafter were generally lower until mid-May.

__ A very cold February in 1979 was also very cold much further south in the Great Lakes and northeastern U.S., a different pairing than Jan 1977. The summer featured a cold June and August and an average July, the result was a cold summer (average 0.3).

__ The winter of 1979-80 had its coldest weather in Dec 1979 and never achieved much snow cover, an early maximum of 25 cms for most of Dec-Jan then slightly less until a heavier cover was established in late May and early June.



ANALYSIS:

The overall climate showed very little change from the 1948-70 period to the 1971-80 decade. Various rather unusual circumstances averaged out to almost the same set of means. The coldest month was in December and March once, January twice, and February six times. That brought the 33-year totals for YRB to December 1, January 8.5, February 17.5, and March 6. Meanwhile the timing of the coldest day of the winter season began to expand to include December (2), and the cumulative totals otherwise were January 10.5, February 13, March 7.5.

The difference between YRB and YCB changed little, from 1.3 milder (coldest months) to 0.3 milder, while the coldest day now averaged 1.3 milder instead of 0.3 as before (so these reversed roles).

While YCB saw a somewhat faster spring melt and less snow in general, YRB trended somewhat in the opposite direction. Now the difference was approaching one month in terms of last snow and last frost. There was also a slight shift at both locations towards more of a bimodal snow distribution although the earlier peak was not reliable or very strong in most winter seasons, and at the same time there was generally more snow in May and June than previously (and it melted later). Several years had basically no summer at all in the 1970s, notably 1972. This was also quite a cool summer in eastern North America especially June and August.

Summers were warming slightly at YCB while they got slightly colder at YRB in this decade. This tendency was strongest 1974 to 1976 and then temporarily reversed in 1978 which was the only summer in the series where YRB managed a warmer month than YCB. June produced one warmest month and July the other nine, but as to the warmest day, June had one, July five and August four (so this perhaps indicates a slight tendency for the warmer summers to spread out into early August on occasion).

Finally, there was a slight tendency for early winter signals to come a few days earlier in the 1970s, but this was probably not greatly significant. There was no room for the first frost to move earlier as almost every year has one within a day or two of August 1st. The actual frost free interval of any interest for YRB is probably more shifted into mid-July, if there even is such a concept worth pursuing.

The average frost free period at YRB over 33 years was a mere 11 days compared with 55 days at YCB. Likely there was a higher average frost-free period if one took the longest one available at YRB whereas the method generally yields the correct result at YCB. The average snow-free interval at YRB is 38 days. This does not prevent frosts and traces of snow from falling in that interval however.

The data and analysis for the 1980s will no doubt be interesting; some climate change signals were beginning to show up at YCB in that decade.






(1981 to 1990)


YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11


1981 __ 307F_ 427F_ ---- _ 45/146 _ 206*_ 212 __ +5 _ 47J _ 165J _ 220 _ 220 _ 286

1982 __ 337F_ 444J_ ---- _ 36/142 _ 204 _ 212 __ --8 _ 48J _ 135 J _ 213 _ 213 _ 289

1983 __ 356F_ 455J_ --- _ 27/148 _ 212a _ 212 __ +3 _ 39J _ 158J _ 220 _ 213 _ 289

1984 __ 356F_ 471M_ --- _ 38/121 _ 209b_ 210 _--23 _ 37J _ 138J _ 217 _ 220 _ 293#

1985 __ 348F_ 448F_ ---- _ 17/124 _ 212c_ 212 _--15 _ 46J _ 131 J _ 213_ 213 _ 283

1986 __341M_466M_(32/-35)_37/143_209_210_ --11 _ 22J%_ 88J _ 213 _ 215 _ 288

1987 __ 362F_ 460F_ ---- _ 27/148 _ 211 _ 212 __ +8 _ 52J _ 140J _ 217 _ 214 _ 291

1988 __ 316J_414F_ ---- _ 18/130 _ 169 _ 177 __--15 _ 62J _ 166J _ 215 _ 230 _ 301

1989 __ 357J_ 453J_ ---- _ 28/134 _ 200 _ 211 __--12 _ 35J _ 142 J _ 213 _ 229 _ 289

1990 __ 373F_487F_38/-85_35/148_ 208 _ 209__ +1 _ 39J _ 111 J _ 215 _ 231 _ 280



means _ 345 _ 453 _32/116_ 31/138 _ 204 _ 208 __ --7_ 43 __ 137 __ 216 _ 220 _ 289

_YCB __ 348 _ 450 __ xxxx _ 40/126 _ 161 _ 175 __ --7 _ 82 __ 211 __ 238 _ 241 _ 291

cumulative 1948 to 1990

means _ 351 _ 460 __33/135_36/139 _ 193 _ 207 ___ 0 _ 43 __ 135 __ 217 _ 226 _ 284

_YCB __ 359 _ 464 __36/128_36/131 _ 164 _ 179 __ --8 _ 81 __ 203 __ 236 _ 247 _ 290



Notes:

*__ The last snow in 1981 was a heavy fall of 8.9 cm on July 25th but otherwise there was no measurable snow on any other days in June or July 1981.

a_ The middle third of July 1983 was a lot warmer than the other two thirds, so for that particular year the last snowfall and frost were more appropriately in early July (1st and 4th). Snow was frequent in the last week of July.

b_ The first ten days of July 1984 were rather warm. The last snow before that interval was on June 27th and the last frost on June 29th. The data in the table are later in July but in this case after the brief summer had come and gone.

# _ Just before this first -20 C reading, a very mild incursion from the southwest took place, temperatures rose to about 1 C on October 13th, with rain reported and considerable snow melt. Pressures fell as low as 979 mbs but winds were rather moderate (veering ESE to WSW as the disturbance passed). This was quite an unusual event for early winter and in fact it had been colder than normal during much of late September, almost reaching the first -20 C then.

c__ Rather mild weather came and went several times in July 1985 but the frost and snow free interval was basically 2nd to 28th of July with slight frosts midway through that interval; more frequent snow and sharper frosts set in at the end of July.

%__ 1986 had a very cold summer, mean of only 0.2 (June -2.5, July 2,2, August 1.0).



ANALYSIS (1981-1990)

Winters remained very close to their long-term averages and as a result, with YCB warming slightly, YRB went somewhat colder in this decade; coldest month was still 0.3 deg less cold than YCB, but extremes were running 0.3 colder. February was most often (7/10) the coldest month and this brought the running totals over 43 winters to December 1, January 10.5, February 24.5, and March 7. The extremes were also dominated by February, and the running totals there are December 2, January 13.5, February 18, March 9.5.

Snowfall dropped off at YRB at roughly the same time that it picked up at YCB. The mean in this decade, 31 cms for peak spring snow, was 8 cm lower than the previous decade and it tended to occur earlier by half a month (mid-May instead of near end of May). Consequently the April to May change in snow depth value also dropped from +3 cm to zero, while YCB went in the other direction, losing 7 rather than 14 cm. The two climates were at this point slowly converging in snowfall figures although not in frost or summer temperatures.

The frost and snow statistics generally cannot change much given that frost usually occurs about one quarter of all days in July and early August near the seasonal boundary. The observed change was just one day at each end of the frost free window (a colder outcome) but snow was observed more frequently near the theoretical limits of the season(s) and the snow-free interval dropped by 27 days at YRB. As discussed in some of the notes, there were several cases where July had a summer interlude mid-month and the method of analysis does not perfectly fit that paradigm, perhaps a more stable frost free period would emerge from a different dividing point.

Summers during the 1981-90 decade at YRB showed no signs of warming although in a longer period analysis 1987 might appear to be a trend-breaking point. Summers were about 1.5 deg warmer on average from 1987 to 1990 than previously and the extremes were up almost 2 degrees. This was a decade where all the summer extremes fell in July.

Finally, the first -20 C minimum drifted about a week later in this decade and by the end was closing the gap with YCB.

M.T. Cranium

means _ 345 _ 453 _32/116_ 31/138 _ 204 _ 208 __ --7_ 43 __ 137 __ 216 _ 220 _ 289

_YCB __ 348 _ 450 __ xxxx _ 40/126 _ 161 _ 175 __ --7 _ 82 __ 211 __ 238 _ 241 _ 291

cumulative 1948 to 1990

means _ 351 _ 460 __33/135_36/139 _ 193 _ 207 ___ 0 _ 43 __ 135 __ 217 _ 226 _ 284

_YCB __ 359 _ 464 __36/128_36/131 _ 164 _ 179 __ --8 _ 81 __ 203 __ 236 _ 247 _ 290

________________________________________________________

1991-2000 data

YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11

1991 __ 353J_ 468J_ 35/-2a_17/135 _211a_211a__--2 _ 51J _ 158J _ 218 _ 223 _ 291

1992 __ 343J_ 428J_ ---- _ 29/151 _ 198 _ 213 _ +14 _ 37J _ 119 J _ 214 _ 215 _ 297

1993 __ 336J_ 436J_ --- _ 20/132b_ 165b_204 __ --7 _ 39J _ 158J _ 216 _ 217 _ 297

1994 __ 337M_ 489M_ --- _ 25/ 89 _ 209 _ 209 _--13 _ 41J _ 148J _ 214 _ 232 _ 285

1995 __333F*_ 451J*_ ---- _ 54/ 90 _ 206 _ 206 _--13 _ 44J _ 127 J _ 221_ 221 _ 284

1996 __330J_451J_(22/-16)_22/ 60 _ 211_ 212 __ --9 _ 35J _ 126 J _ 214 _ 214 _ 281

1997 __ 356F_ 462F_ ---- _ 34/138 _ 209c_ 211 __ --2 _ 37J _ 132J _ 213 _ 216 _ 285

1998 __ 350F_ 443F_ ---- _ 18/131 _ 193 _ 193 __--17 _ 56J#_ 146J _ 214 _ 230 _ 287

1999 __ 330J_428J_30/-56_22/153 _ 199 _ 196 __ +2 _ 50J _ 148A^_ 226 _ 235 _ 289

2000 __ 336J _ 448J_ ---- _36/150 _ 195 _ 199 __ +4 _ 44J _ 169J _ 222 _ 222 _ 289

(note: 3a actual snow depth peak incl early cases, counts only the two cases that produce a greater snow depth -- a third case in brackets is not factored in -- this is in reference to the 31/ 88 entry. The other eight data points are the same as those in column 3b. So what this tells us is that the actual mean is 31 cms on day 88, but the later peak on average is 28 cms on day 123. )

means _ 341 _ 450 _31/ 88_ 28/123 _ 200 _ 205 __ --4_ 43 __ 143 __ 217 _ 223 _ 289

_YCB __ 332 _ 443 __ xxxx _ 42/133 _ 166 _ 173 __ --8 _ 94 __ 225 __ 240 _ 243 _ 295

cumulative 1948 to 2000

means _ 349 _ 458 __34/132_34/136 _ 194 _ 207 __--1 _ 43 __ 136 __ 217 _ 225 _ 285

_YCB __ 354 _ 460 __37/129_37/132 _ 165 _ 178 __ --8 _ 84 __ 207 __ 237 _ 246 _ 291



Notes:

a__ The maximum snow depth for this winter (1990-91) was set on Dec 29, 1990 which is day -2 of the winter. A weak secondary maximum was set in mid-May. Then the summer of 1991 featured some rather warm conditions July 14-23, the last frost and snow before that interval came on July 4th (day 185).

b__ Data for winter 1992-93 are sporadic, daily reports occur in clusters of 2-3 days about a week apart for most of the season. Therefore the peak snow depth could have been greater at some point than this report. Daily reports became more frequent through June and only two days (2nd and 25th) are missing from July. Still, there is some chance that the last snow was later than shown here (June 14th). Data are missing for Aug 2-3, so the first frost and snow dates could be 2 days earlier. About five days are missing from October and the first -20 C could have been earlier than shown, although most of the days that do appear before the 24th are quite mild.

* __ Winter 1994-95 was uniformly cold with heavy snow pack that had already reached 45 cm in December and stayed close to 50 cm through Jan-Feb-Mar. These months all had minima of -45 but the January extreme was based on that one being -45.1 (the other three months had a -45). By the way, data had returned to being continuous daily by this point. Unusually mild and dry conditions prevailed in April and the snow pack slowly reduced to 40 cm. May turned somewhat colder than late April but snow continued to reduce slowly through the month.

__ Winter 1995-96 had small snow packs in the 20-22 cm range for most of November through early May. The max dates shown are not very different from this entire period.

c __ Brief warm spell 20-24 July, last snow before that was June 3rd (day 154).

# __ 1998 had a longer than usual "summer" with June's mean temperature 3.8, July 5.8 and August 2.9 C. June 28 to July 4 and most of mid to late July were mild, as also August 10-12.

__ Winter 1998-99 saw early buildups of snow pack that peaked on Nov 5th 1998 and after reducing later that month, never came within 10 cms of that same depth in the spring secondary maximum of May 1999.

^ __ The first ten days of August 1999 were probably milder than any other period in August to date, and continued the general sporadic warmth of July; even so, light frosts and snowfalls occurred between some July warm spells. Colder weather in late August prevented the month from being the warmest of the year.



ANALYSIS (1991-2000)

Winters at Resolute became slightly milder during this decade, by about 1 degree, keeping pace with warming at YCB. The coldest months were in January 6 of the ten winters, February 3 times and March once, bringing the cumulative frequency for 53 winters to

December 1, January 16.5, February 27.5, and March 8.

The daily coldest extremes were also dominated by January (7 cases, 2 in Feb and one in March), bringing the cumulative totals there to

December 2, January 20.5, February 20, March 10.5.

All of this suggests that winter is being forced back into its central time period, with fewer examples found of extremes at the edges of the season. However, this should not be overstated given that it routinely fell into the -40 to -45 range every winter in the decade (and sometimes a bit lower).

The frost and snow parameters showed slight tendencies to a longer pause in the brief northern summer. However, more significant, the average snow depth fell by about 8 cms and there was a continued tendency for the bimodal distribution established in the 1980s to continue. To put it in easily visualized terms, snow was more often disappearing by mid-June instead of late June, and was slower to appear in stages in late August to early October (although once or twice there was a large autumn snow pack established).

Summer changes were not as pronounced as at YCB, in fact, the warmest month matched the previous decade (4.3 C), while the extreme maximum advanced only a few tenths; at YCB these parameters increased by a full degree in this decade.

Although summer's greatest warmth continued to be almost exclusively a July phenomenon, two cases of significant early August warmth appeared near the end of the decade.

Finally, the onset of -20 C minimum temperatures continued to drift later into October and the difference between YRB and YCB remained similar, so both locations were seeing the full onset of winter about a week later (for YRB getting closer to the 20th of October and for YCB the last few days of October). This seems like a fairly obvious response to larger ice-free expanses in the regional oceans and seas.

This YRB study will conclude in the next post (which I have reserved for that purpose) -- and it may be up tonight or tomorrow morning. Once again, I have not looked and I don't know what's around that bend. Except that I do know 2007 was quite warm as I looked at that summer in some detail for my own interest shortly after the ice free maximum north of Siberia and Alaska in October 2007.



2001-2010 data

YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11

2001 __ 315J_ 418F_ ---- _ 30/129 _ 186 _ 210 __--4 _ 48J _ 128A _ 224 _ 225 _ 284

2002 __ 341F_ 450F_ ---- _ 20/146 _ 208 _ 212 __--4 _ 25J _ 112 J _ 213 _ 227 _ 302

2003 __ 344F_ 423F_ ---- _ 15/151 _ 211 _ 212 __ +3 _ 50J _ 151J _ 213 _ 222 _ 286

2004 __342M_449M_48/ 4a_ 8/105a_ 213_ 213 ___ 0 _ 22Jb_ 86J _ 214 _ 214 _ 291

2005 __323D_430M_24/-40c_ 10/101 _ 163 _ 212 _--3_ 39J _129A _ 226_ 244 _ 284

2006 __303J _ 440M_

---

_ 24/123 _ 205 _ 206 _ --14 _ 44J _ 155 J _ 230 _ 258 _ 304$

2007 __ 342M_ 469M_ ---- _ 45/135 _ 150 _ 212 __ --4 _ 74J%_ 179J _ 213 _ 264 _ 288

2008 __ 353F_ 437F_32/ 2 _ 24/ 96 _ 201 _ 202 __--16 _ 53J _ 185J _ 223 _ 226 _ 290

2009 __ 319M_407M_ ---- _ 22/101 _ 187 _ 194 __ --7 _ 53J _ 149J _ 233 _ 233 _ 295

2010 __ 306J _ 412F_33/-3_21/137 _ 162 _ 205 __ +4 _ 54J _ 174J _ 215 _ 215 _ 299



means _ 329 _ 434 _29/ 79_ 22/122 _ 189 _ 208 __ --4_ 46 __ 145 __ 220 _ 233 _ 292

_YCB __ 329 _ 440 _40/126_ 40/126_ 172 _ 174 __ --6 _ 92 __ 214 __ 246 _ 260 _ 297

cumulative 1948 to 2010

means _ 346 _ 454 __35/128_32/134 _ 193 _ 207 __--2 _ 43 __ 138 __ 218 _ 227 _ 286

_YCB __ 350 _ 457 __37/129_37/131 _ 166 _ 177 __ --8 _ 85 __ 208 __ 238 _ 248 _ 292



Notes:

a __ A deep snow pack built up during the last two months of 2003 and peaked at 48 cms in late December to Jan 4, 2004. After this, despite very cold weather, the reported snow depths slowly diminished all the way to the end of May. The secondary peak of 8 cm on April 15 is much below the average amount for early June in all years.

b __ The summer of 2004 was very cold. The mean temperature was 0.7 C, June at -1.6, July at 2.2 and August at 1.6 C.

c __ Heavy snow fell Nov 17-18 2004, 32 cm in two days, probably the heaviest fall at this location. The peak snow depth followed, then the rest of the winter saw gradual depletion, with a skimpy 10 cm in mid-April a very weak secondary peak. This was the second winter in a row following this previously unseen pattern.

$ __ This very late entry (Oct 31, 2006) was consistent with a very mild period from late July to the end of October. While most of July was quite cold, a warm spell suddenly developed around July 28th, and persisted well into August. September had very little snow, and October ran about 10 degrees above normal temperatures, the mean for the month was -6.0 C.

%__ The summer of 2007 was warmer than any other in the series. Mean temperatures were 1.3 June, 7.4 July and 4.9 August. The daily maximum of 17.9 on July 11 was also a record (which would be broken in July 2008 also on the 11th). The second half of July into early August was not as warm but it then turned very mild in mid-August again. Perhaps more significant, there was no measurable snow from May 31st to September 21st, a much longer snow free season than normal (although quite a few traces of snow here and there in that interval). Frosts just happened to fall at the season boundary but many days in July and August were frost-free.

---

-- --

---

ANALYSIS 2001-2010

Winters warmed up by about 1.5 degrees in this decade compared to the 1990s. They ran about 3 degrees milder than the base values for 1948-80. The coldest month occurred later on average with three cases in February and three in March. This brought the cumulative totals over 63 winters to

December 2, January 19.5, February 30.5, and March 11.

The daily coldest extremes were also dominated by February and March with five cases each, bringing the cumulative totals there to

December 2, January 20.5, February 25, March 15.5.

Peak snowfall was only 22 cms on average in the spring and this was becoming more frequently a secondary maximum, the overall average peak depth was 29 cms and sometimes this would occur in the months before New Years Day. The blended average date (day 79) is really a blend of two different peaks in Nov-Dec and Apr-May. The snow loss during May continued about the same as before although from a smaller base. These were similar trends to those observed at Cambridge Bay.

Summers on average warmed slightly but this was a blend of a cold first half and warm second half of the decade. Both 2002 and 2004 were very cold, 2006 to 2010 generally warmer than the long term average by 2-3 degrees. Record highs were set in both 2007 and 2008. The summers began to lengthen into late June and the first half of August from their usual narrow July focus. More snow-free summer months were recorded. A frequency analysis for summer warm months and days will be constructed in the final six-year period analysis.

Frost and snow free intervals began to expand too, the onset of winter snow moved back into late August by about ten days. Some years had very little snow until late September. The first -20 C minimum also shifted a few more days later into October. There were several years in this decade when -20 C onset was very close to the end of October, but so far this has avoided November (YCB has been that late twice). The onset dates are slowly converging at the two locations, moving one day closer each decade (while both get later in the season, so the rate of change at YCB is greater).

______________________________________

______________________________________

Data for 2011-19 (edited forward in Dec 2019, original post Apr 2017)

YEAR ___ 01 __ 02 __ 03a __ 03b __ 04 __ 05 __ 06 __ 07 __ 08 ___ 09 __ 10 __ 11

2011 __ 322F_ 443J_ ---- _ 33/103 _ 175 _ 164 __--6 _ 88J*_ 187J*_ 230 _ 248 _ 290

2012 __ 326M_ 412F_ ---- _ 38/ 34 _ 206 _ 209 _ -10 _ 73J _ 201 J*_ 225 _ 224 _ 300

2013 __ 354F_ 474F_ --- _ 26/ 65 _ 208 _ 210 __ --8 _ 31J _ 116A _ 220 _ 228 _ 299

2014 __324J _ 421F_ ---- _ 23/153 _ 153_ 202 _ +12 _ 37J _ 105J _ 213 _ 214 _ 293

2015 __333F_ 413M_---- _ 17/121 _ 162 _ 167 __ --6_ 79J _169J _ 217 _ 253 _ 286

2016 __304F_ 403F_32/-87_28/129_ 202_ 196 __ --6 _ 58J _ 139J _ 215 _ 216 _ 293

2017 __311M_ 476M_ ---- _ 34/ 93 _ 196 _ 209 __ --9 _ 33J _ 115A _220 _ 220 _ 297

2018 __319F_ 437M _ ---- _ 32/118 _209 _ 212 __--12_ 19J _ 140J _ 213 _ 227 _ 287

2019 __317J_ 420J _ 29/-7_ 25/119 _174 _ 204 __ -15_ 55J _ 162J _ 232 _ 255 _ 300



means _ 323 _ 433 _29/ 66 _ 28/104 _ 187 _ 196 __ --7_ 53 __ 148 __ 221 _ 231 _ 294

_YCB __ 324 _ 428 _37/130_ 37/130_ 157 _ 172 __ --7 _ 94 __ 211 __ 244 _ 251 _ 297

cumulative 1948 to 2019

means _ 342 _ 451 __34/125_32/130 _ 193 _ 205 __--3 _ 44 __ 139 __ 218 _ 227 _ 287

_YCB __ 346 _ 456 __37/128_37/130 _ 164 _ 177 __ --8 _ 87 __ 208 __ 238 _ 250 _ 293



Notes:

* __ Summer 2011 was even warmer than any of the previous five. July at 8.8 and July 9th at 18.7 set new records. The summer means were 2.8 June, 8.8 July and 5.3 August. No snow fell from June 25th to Sept 4th. .... In late June and early July of 2012, even higher temperatures occurred, including 20.1 on July 2, 2012. The month from June 24th to July 23rd averaged close to 10 C. But no calendar month exceeded July 2011.

==============================

Analysis (2011-2019)

These past nine winters have seen similar averages to the decade 2001-10. YCB showed more tendency to warming than YRB in this interval. The coldest months at YRB continue to be frequently February or March. The cumulative frequency for the full period of the study to date is

December 2, January 21.5, February 35.5, and March 13. (total 72)

The daily coldest extremes were also dominated by February and March again, bringing the cumulative totals there to

December 2, January 22.5, February 29, March 18.5. (total 72)

The spring snowfall peak showed some resurgence after its long-term minimum in the previous decade. YCB in this recent nine winter period has seen less snow than in the previous decade, so trends are opposite in this element. However, at YRB, only 2014 had a peak well into the season, and two years were quite early (before March) while two others (2016,19) had a bimodal distribution.

The snow and frost free seasons began earlier than before by about ten days (this basically means more frequent warm weather in July). The seasons ended about the same time they had in the previous full decade. And the -20 onset was just two days later on average. These are all similar trends to YCB for the six summers.

Summers at both locations are warming although relative to the entire decade and not to the stronger warming 2006-10; that warming seemed to continue at YRB for two more years before settling back into the previous sort of dull mildness. The average for 2013-16 has been 5.1 for warmest month and 13.2 for warmest day. The averages for 2007 to 2012 were 6.6 and 18.0, clearly a much warmer interval. Then 2018 produced one of the coldest summers on record with the warmest month only 1.9 C (July).

The frequency of warmest month and warmest day over the 69 summers in the period of study are:

WARMEST MONTH ____ 1 June, 68 July, 3 August

WARMEST DAY _______ 1 June, 57.5 July, 13.5 August

___________________________________________________

M.T. Cranium

Here's another measurement of subarctic winter cold, the lowest temperature in each winter at Dawson, Yukon from the winter of 1898-99 to the present. Once again, will be maintaining this one going forward.

In the table, years identify the winters by their Jan-Mar calendar months. They include the Nov-Dec of the previous year, The station is located near the Yukon-Alaska border about 64 deg N lat. (edit -- see more detailed information on station location and move of recording site Feb 1979 at bottom of the post)

Decade ___ 00 __ 01 __ 02 __ 03 __ 04 __ 05 __ 06 __ 07 __ 08 __ 09 ____ avg

1899 ____ ---- __--- __--- __---- __--- __ --- __---- __--- __--- __ -42.8

1900-09 _-48.9_-55.6_-45.6_-51.7_-50.0_-46.1_-55.0_-50.6_-42.2_-53.9 __ -50.0

1910-19 _-47.8_-52.2_-52.2_-52.2_-46.7_-38.3_-50.0_-50.6_-52.8_-45.0 __ -48.8

1920-29 _-50.0_-47.2_-47.2_-44.4_-47.8_-52.2_-39.4_-43.3_-46.7_-46.1 __ -46.4

1930-39 _-49.4_-43.3_-52.2_-52.8_-54.4_-48.9_-51.2_-47.8_-47.8_-48.3 __ -49.6

1940-49 _-45.6_-44.4_-46.7_-48.9_-42.2_-41.7_-40.0_-58.3_-43.3_-50.0 __ -46.1

1950-59 _-51.2_-51.2_-54.4_-48.3_-47.8_-49.4_-50.0_-50.6_-43.3_-53.3 __ -49.9

1960-69 _-45.6_-43.9_-54.4_-52.8_-48.3_-54.4_-50.6_-51.7_-54.4_-51.2 __ -50.7

1970-79 _-48.9_-56.2_-52.8_-52.2_-48.9_-52.8_-52.2_-40.0_-48.9*_-55.8__ -50.9

1980-89 _-53.8_-51.8_-50.2_-51.4_-49.9_-49.6_-43.5_-46.3_-43.5_-51.2 __ -49.1

1990-99 _-52.2_-47.8_-42.4_-50.2_-50.3_-45.1_-50.0_-52.0_-47.5_-48.0 __ -48,5

2000-09 _-47.5_-42.5_-42.0_-42.0_-48.5_-50.5_-45.5_-48.7_-51.3_-50.3 __ -46.9

2010-19 _-46.0_-47.4_-46.2_-50.3_-46.7_-47.1_-35.9_-42.6_-44.9_-44.3 __ -45.1

2020 ___ (-47.5) Jan 10 (to be updated)

* Jan 1978 old and new stations both reporting data, the new location (CYDA) supplies the data from Feb 1979 and thereafter. The minimum at CYDA for the same month was -51.0. See note at bottom of the post.

About half of winters have this minimum in January with a strong peak of dates in the mid-month interval. The list below shows which winters had a minimum in another month: It is possible for temperatures to fall as low as -40 C from about 7th November to early April although such readings are rare outside the span of late November to early March. With ties counting 0.5, in 102 winters to date, the minimum has occurred 2.5 times in NOV, JAN 53 (56 cases, six tied with DEC or FEB), DEC 22 (24 cases, 4 ties with JAN), FEB 24.5 (26 cases, 2 tied with JAN, 1 with NOV) and MAR counts zero but has had six near misses. APR 1944 had a reading cold enough to be a winter minimum in the least extreme cases.

NOV _ 30th (1930, mild through the winter, second cold spell mid-March 1931 reached -41.6).

__ 15th-16th (1945-46) tied with 10th Feb 1946 _ 21st (1986-87)

DEC _ 31st (1901-02)* _ 25th (1917-18) _ 15th (1918-19) _ Dec 6 (1925)^^ _ Dec 28 (1927-28)

____ 31st (1929-30)* _ 21st-22nd (1936-37) _ 8th (1941-42) _ 29,30,31 (1944-45) _

____ 7th-8th (1948-49) _ 31st (1949)* _ 29th-30th (1954-55) _ 12th (1956-57) also -50.0 Feb 12 1957.

____ 30th (1961-62) .. Jan 27th, 1962 almost as cold (-53.9) _ 11th (1966-67) _ 10th (1975-76)

____ 5th-6th (1976-77) _ generally a milder than average winter _ 5th, 9th (1977-78) _ 28th (1980-81)

____ 4th-5th (1990-91) _ 4th (1991-92) _ 1st (1994-95) __ 31st (1999-2000)* _ 17th (2000-01)

____ 25th (2015-16) _ a very mild January followed, Feb somewhat colder

FEB _ 4th (1908), 2nd (1910)** _ 17th (1915)^ _ 1st (1917) by 0.6 _ 6th (1921) _ 10th (1922)

____ 23rd (1932) _ 8th-9th (1939) _ 7th (1943) _ 10th (1946) tied with Nov 15, 16 1945.

____ 3rd (1947) in this extreme spell, -63 C at nearby Snag was the all-time North American low. ..

______ Jan 1947 averaged -31.6 and had fallen to -52.8. There was also a reading of -51.7 on 13-14 Dec 1946.

____ 16th (1948) _ 17th (1954) -- tied with 28th Jan, corrupted data for most of Jan, not certain a lower value

______ did not exist. __ 9th (1958) _ 21st, 22nd (1961) _ 5th (1963) _ 3rd (1968) _ 11th (1979)

______ 12th (1985) _ 18th (1986) _ 4th (1993) _18th (2003) _ 23rd (2007) _ 12th (2014) __ 6th, 7th (2015)

______ 7th (2018) _

MAR _Mar 1908 (-41.1) came within 1.1 of the February minimum.

_____ Mar 2 1956 was -47.8, within 2.2 of the January 1956 min.

_____ Mar 7th 1961 (-43.3) was within 0.6 of the February 1961 min.

_____ Mar 5th 1987 (-45.2) was colder than any days Dec 1986 to Feb 1987 but not Nov 1986.

_____ Mar 13th 2003 (-41.5) was within 0.5 of coldest day Feb 18th 2003.

_____ Mar 2nd 2007 (-47.5) was within 1.2 of coldest day Feb 23rd 2007.

APR _ (In 1944 the Jan min of -42.2 was almost broken on April 3 -40.6).

* tied coldest Dec 31 1901 and Jan 1 1902 and also Dec 31 1929 and Jan 1 1930 (Feb 15 within 0.5). A third similar event was Dec 31 1949 and Jan 1 1950 (followed by record cold throughout western Canada). Then Dec 31, 1999, tied with three days in January 2000 for coldest of that winter.

** tied coldest Feb 2 1910 with Jan 10, 11, 1910.

^ a much milder Jan 1915 than most, -31.3 the lowest temp, both Dec 1914 and Feb 1915 colder.

^^ another very mild Jan 1926 with another colder spell late Feb 28 (-38.9) within 0.5 of the Dec 6 minimum.

___________________________________________________________________________________

LOCATION INFO: The town of Dawson (pop 1500) is located at the confluence of the Yukon and Klondike rivers. The first recording site (1898-1902) has a lat-long which places it 10 km east of Dawson and 1 km north of the Klondike highway running east-west at that point. I suspect this was an approximation since there is no sign of human activity there (it is north of the river, all human activity is to the south). The elevation is given as 320m asl. By 1902, the station was either relocated or better identified at a position which is 1 to 2 km east of Dawson near the current baseball diamond and recreation hut (same elevation). The area is flat with a glacial moraine type hill to its north. In 1978 a weather station was opened at the airport (CYDA) located about 20 km east of this first site, beside the same (and only access) highway at 370m asl. After Jan 1979 the longer-reporting location ceased reporting but we have overlap for one full winter and parts of a second one. This overlap shows that the airport location is 1 to 2 deg colder on average in colder months, including on coldest nights. For the winter of 1977-78 the average temperature difference was zero, but one mild month (Feb 78) was 2 deg milder while the other two were each one degree colder at the airport. The three monthly extremes were all colder at the airport by 0.9, 2.1 and 0.3 deg. There was a difference of one degree in Jan 1979 (but the extreme comes from a very cold Feb 1979 with only the airport reporting at that point).

I have drawn the conclusion that the colder half of the data 1979 to 2019 may be 1 to 2 deg colder than a comparative sample of that colder half 1899 to 1978, but that the milder half the data may be more equally comparable.

==============================================================================

ANALYSIS of the data series

Briefly, the analysis shows that there have been three milder intervals, one lasting approximately 1919-31, another from 1940-46, and then generally speaking since about 2001 to present with 2008 and 2009 somewhat colder to produce 2001-07 and 2010-19. (This is the winter of 2020 in the same time scale, and so far it seems on course to get back to somewhat colder values). Within each mild spell there appears to be one to three particular winter(s) that were exceptionally mild and therefore likely dominated by Pacific air masses due to ridge development near 130W, and these were the winters of 1926, 1944-46, 2002-03 and 2016. The winter of 1975-76 was also quite mild but fell within a generally cold interval.

The coldest five-winter average and ten-winter average would identify the interval 1965 to 1975 as the coldest part of the data series although it was just about at the same level in the decade of 1900-09 and in the mid-1930s and 1950s. The early 1980s remained very cold, then warming seemed to begin, however it backed off during the 1990s (albeit the data should be reduced by 1-2 deg for direct comparison to decades before 1980).

A note to any researchers thinking of using Dawson data: some of the very early cold interval reports have only daily minima during extreme cold spells (because presumably going outside once a day was more than enough for the recorder) and so the averages which are still tabulated anyway are incorrect for these months as only the non-extreme cold days have a maximum reported. This practice seemed to fade out of the data after 1910. Also, the winter of 1953-54 have some evidently incorrect data, for one thing, only minima are reported, but a good number of the January minima seem to be entirely erroneous (numbers well above 0 interspersed with more authentic looking numbers) while Feb 1954 has what appears to be correct minima. I would suggest some additional quality control might be needed for January 1954 data from the station.

M.T. Cranium

The data are shown in an excel file with various graphs making things easier to visualize.

The only other stations with long periods of data in the arctic islands would be Mould Bay in the northwest, Eureka in central Ellesmere Island, and Iqualuit on southeast Baffin Island. I hope to add some data from them to the files but an inspection of data at Mould Bay suggests that all the trends will be similar to Resolute. Warmings in some recent summers that were higher temperatures than normally seen at Resolute tended to appear at Mould Bay a few days later, suggesting that warmth is moving west rather than east when it does appear.

The typical difference is about 2-3 C deg (Mould Bay reaches lower peaks by that amount). Eureka has some small downsloping effects as it is surrounded by fairly high elevations but is itself near sea level. With a longer period of winter darkness it may have a longer range of coldest month or days.

My overall conclusion from all data studied is that the Canadian arctic has warmed up by about 2 C deg in winters and 1 C deg in summers since the middle of the 20th century. How much of that is due to warmer ocean temperatures and how much attributable to air mass frequency change is of interest, but it would seem that the main warming mechanism is more intrusion of southern air masses indicating that circulation change is more significant than air mass modification. Both may be occurring however. That statement does not necessarily have any direct implication on the question of the source of climate change (natural variability or human activity, or a blend). Either one could in theory change the circulation patterns. But it's fairly obvious to me that milder air is reaching the Canadian arctic in winter on a more frequent basis than in the past. Even so, it does not reside there very long. My estimate is that instead of 2-3 days a month with these incursions, we now see 4-5 days. The rest of the time is still (in a normal winter) bitterly cold. The winter mins seem to be more dependent on snow cover than further south where air mass advection over any amount of snow is the main variable.

When Dawson has had its lowest temperatures there has often been heavy autumn and early winter snowfalls. Snow cover at Dawson can range from 20 to 120 cms in various winters. It's a bit complex since a very snowy winter could be caused by a storm track closer to central Yukon and more cloud, which would inhibit radiational cooling and strong high pressure. The ideal scenario for bitter cold to develop is for strong arctic highs of 1050-1060 mb to build up over Alaska and Yukon, NWT after a snowfall. Highs of 1035-1050 mb can create bitter cold but are more often restricted to the -30s and low -40s.

M.T. Cranium

I was just able to edit the lowest temperature of this current winter at Dawson YT (-47.5 at a recent hour) which is the lowest temperature there since 2013 (-50.3). Not sure if that will hold up as a prolonged cold spell is developing across all of western Canada. We have not been below -10 C at my location yet, but are expecting -25 to -30 by Tuesday morning. Dawson also has a healthy snow pack this winter of nearly 60 cms. We have about 25-30 cms here and 35-40 on nearby hills. (my location is 15 deg of latitude south and 20 deg of long east of Dawson and my elevation is 1010 m asl compared to their 370m.)

I have not corrected the data point for Dawson 2020 on the linked excel file (it would be in cell EA 122) if you have downloaded or if you just opened it up, you can correct it and the five-year average function in EB 120 will adjust automatically.

M.T. Cranium

Here are some similar data (compaed to Cambridge Bay and Resolute) for Eureka, which is further north located in central Ellesmere Island, at 80N 86W and just 10 meters above sea level in a glacial valley surrounded by permanent ice fields and glaciers. Since the summer here is quite brief, I have left out the variables such as last frost, last snow cover, first frost and first snow cover. We'll check the trends on temperatures of both extremes, maximum snow depth and first autumn -20 C reading.. It should be noted that the prevailing climate is much drier than in the central arctic islands, and 10-15 cm snow cover is quite typical with strong winds sometimes leading to patches of bare frozen ground.

The climate is drier than further south, and is known as "arctic desert" although it does support some scrubby vegetation that persist despite a very short growth season mid-June to early August. Most summers have very little rain and can continue to see sporadic light snowfalls, but one or two cases were noted of 25 mm rainfalls. A daily snowfall of more than 10 cm would be unusual at any point in the season. One heavier snowfall noted was 18 cm Sept 17-19 1966. The snow pack stays fairly constant once it reaches maximum depth and only begins to melt at the very end of May or first week of June. |At this latitude, darkness begins in early November and lasts until mid-February. Continual daylight begins in late April and persists to early August.

The min temp and coldest month could be in the preceding Nov or Dec although usually as shown they are in the part of the winter in the same calendar year. So what is showing is the coldest reading of each winter, not each calendar year.



YEAR ____ Min temp _ coldest mo __ Max snow depth ___ Max temp _ warmest mo __ first -20

1948 _____ -52.8 Mar __ -42.6 Feb __ _____________ ___ 18.9 Jul ___ 6.2 Jul _____ Sep 17

1949 _____ -49.4 Dec __ -41.8 Dec __ _____________ ___ 15.0 Jul ___ 5.9 Jul _____ Sep 29

1950 _____ -50.6 Feb __ -42.0 Jan __ _____________ ___ 19.4 Jul ___ 6.1 Jul _____ Sep 17

1951 _____ -50.0 Jan __ -40.3 Feb __ _____________ ___ 15.6 Jul ___ 5.7 Jul _____ Sep 27

1952 _____ -51.2 Jan __ -38.8 Dec __ _____________ ___ 16.7 Jul ___ 6.7 Jul _____ Oct 1

1953 _____ -50.6 Mar __ -39.6 Feb __ _____________ ___ 12.8 Jul ___ 4.2 Jul _____ Sep 23

1954 _____ -47.8 Feb __ -38.4 Jan __ _____________ ___ 16.1 Jun ___ 5.6 Jul _____ Oct 2

1955 _____ -48.9 Feb __ -40.1 Mar __ _____________ ___ 13.3 Aug ___3.8 Jul,Aug _ Oct 2

1956 _____ -52.2 Mar __ -37.7 Mar __37 cm Apr 17-Jun 2 _ 14.4 Jul ___ 5.5 Jul _____ Sep 23

1957 _____ -48.9 Jan __ -40.5 Jan __ 10 cm Mar 1-May 14_ 17.8 Jun __ 6.8 Jul _____ Sep 29

1958 _____ -52.2 Feb __ -41.5 Dec __23 cm Jan 23-May 17_18.9 Jul __ 5.8 Jul _____ Oct 2

1959 _____ -48.3 Feb __ -39.6 Mar __20 cm Jan 20-May 31_16.7 Jul __ 6.3 Jul _____ Sep 29

1960 _____ -51.2 Mar __ -39.5 Mar __23 cm May 6-14 _____17.2 Jun __ 6.6 Jul _____ Oct 1

mean _____ -50.3 _____ -40.2 _____ 23 cm Mar 7-May 10 __16.4 _____ 5.8 ________ Sep 27



1961 _____ -51.2 Mar __ -39.7 Mar __18 cm Feb 18-May 30 _15.6 Aug _ 4.5 Jul _____ Sep 14

1962 _____ -46.7 J, F __ -39.1 Feb __ 28 cm Apr 1-29 _____ 18.3 Jul __ 7.5 Jul _____ Sep 26

1963 _____ -48.9 Jan __ -39.1 Mar __ 28 cm Feb 11-May 27_ 15.0 Jul __ 5.8 Jul _____ Sep 29

1964 _____ -51.2 Mar __ -38.8 Mar __ 25 cm Apr 30-May 7 __12.2 Aug _ 3.7 Aug _____Sep 28

1965 _____ -45.2 Feb __ -37.2 Feb __ 15 cm May 7 - 21 ____ 16.7 Aug _ 4.1 Jul _____ Sep 20

1966 _____ -53.3 Jan __ -39.4 Mar __ 18 cm May 11-21 ____ 14.4 Aug _ 5.3 Aug _____Sep 25

1967 _____ -51.7 Feb __ -41.7 Feb __ 23 cm Jan 4-Apr 4 ___ 14.4 Jun _ 4.5 Jul _____ Sep 25

1968 _____ -51.2 Jan __ -40.0 Jan __ 20 cm Feb 24-Apr 30 _ 18.3 Jul __6.3 Jul _____ Sep 29

1969 _____ -48.3 Mar __ -38.6 Mar __ 18 cm May 9 - 21 ____ 13.3 Jun _ 4.6 Jul _____ Sep 19

1970 _____ -50.6 Jan __ -37.9 Feb __ 30 cm Apr 10-May 22 _ 13.3 Aug _ 5.3 Jul _____ Sep 24

mean _____-49.9 ______-39.2 ______22 cm Mar 26- May 12 _ 15.2 ____ 5.2 ________Sep 24

======================================================

In these first 23 years of data, not much change decade to decade, there was a slight decrease in the summer temperature parameters and the -20 C season began a bit earlier (by three days). Will be posting the continuation of these tables over the next 2-3 days.

YEAR ____ Coldest min and month ___ Max snow depth ______ Warmest max and month __ First -20 C

1971 _____ -48.9 D, F __ -42.5 Feb __ 30 cm May 7-20 ________ 17.2 Jul __ 7.0 Jul _____ Sep 24

1972 _____ -53.9 Feb __ -39.4 Jan ___23 cm Mar 10 - June 3 ___ 11.7 Jul __ 4.6 Jul _____ Sep 20

1973 _____ -52.8 Feb __ -43.2 Feb __ 28 cm Apr 4 - May 1 _____ 11.1 Jul __ 4.5 Jul _____ Sep 26

1974 _____ -50.6 Feb __ -42.3 Jan __ 18 cm Apr 16 - June 22 ___ 12.8 Jul __ 4.8 Jul _____ Sep 22

1975 _____ -51.7 Feb __ -42.9 Feb __ 25 cm Nov 14-27 1974 ____16.1 Jul __ 4.9 Jul _____ Sep 26

1976 _____ -47.8 Mar __ -37.5 Feb __ 28 cm Apr 3 - May 31 _____18.9 Jul __ 5.1 Jul _____ Sep 21

1977 _____ -50.5 Mar __ -42.2 Mar __ 23 cm Jan 16 - Feb 6 _____ 17.5 Jul __ 6.7 Jul _____ Sep 25

1978 _____ -50.8 Dec __ -39.9 Dec __48 cm May 13 - 22 ________17.3 Jul __ 6.8 Jul _____ Sep 27

1979 _____ -55.3 Feb __ -47.9 Feb __ 20 cm Apr 13 - May 2 _____ 14.5 Jul __ 5.2 Jul _____ Sep 14

1980 _____ -49.8 Jan __ -38.4 Dec __ 34 cm Mar 21 - 27 ________14.7 Jul __ 5.5 Jul _____ Sep 17

mean _____-51.2 _____ -41.6 ______28 cm Mar 18 - Apr 18 _____15.2 Jul__5.5 Jul _____ Sep 22

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ANALYSIS: The 1970s began with some very cold years, 1972 to 1974 failed to warm beyond about 12 C and had warmest months (always July in this decade) below 5.0. This reversed to some extent in the later 1970s with some rather warm readings. The winters were generally a bit colder than previous decades, and reached new minima in 1972 and again in 1979 (-55.3) during a widespread very cold month in eastern North America. To the end of this decade there is no sign of any warming trend overall but a few years began to display signs of it. Similar to Cambridge Bay, winter 1974-75 had an anomalous early winter snow depth peak in November 1974. This pulled back the average duration which otherwise would have run from early April to early May on average. The decade had somewhat heavier snow cover than previously. The winter of 1977-78 had particularly heavy snow cover for this location. It had reached its usual late winter depth before the end of 1977 and continued to accumulate with small snowfalls in the heart of the winter season. Some mid-winter periods have no measurable snow and changes can only occur through wind redistribution, which is unusual due to prolonged anticyclonic intervals and rather calm conditions. Stronger winds occur in summer as different surfaces are heated and sometimes gusts over 100 km/hr occur in dry weather in July.

We are now in a position to set the 1951-80 "normal" based on those years from previous post and this one. Data from 1948 to 1950 are not included in these.

1951-80 _____ -50.4 __ -40.0 ____ 24 cm Mar 19 - May 2 _____ 15.5 ___ 5.5 _____ Sep 25

The trends within this 30-year interval are faint, but slightly towards a colder regime with more snow and earlier winter onset.

Frequencies of coldest and warmest (0.5 for ties) -- these data include 1948, 49 and 50.

Coldest Days ___ 2.5 Dec, 8.5 Jan, 13.0 Feb, 9.0 Mar ______ Warmest Days __ 4 Jun __ 23 Jul __ 6 Aug

Coldest Months _ 5 Dec _ 6 Jan _ 12 Feb _ 10 Mar _________Warmest Months _______ 30.5 Jul _ 2.5 Aug

Now we can start to track how that changed, if at all, from 1981 to the present time.

=============================================

1981 _____ -46.3 Feb __ -37.7 Mar __ 13 cm Apr 14-20 _____ 17.2 Jun __ 5.9 Jul _____Sep 27

1982 _____ -47.9 Mar __ -39.0 Feb __ 18 cm Apr 19-27 _____ 14.2 Jul __ 5.1 Jul _____ Sep 24

1983 _____ -50.2 Feb __ -37.8 Feb __ 19 cm Apr 10-12 _____ 13.6 Jul __ 5.7 Jul _____ Oct 4

1984 _____ -51.3 Mar __ -44.1 Feb __ 20 cm Feb 4-12 ______ 15.2 Jul __ 5.3 Jul _____ Sep 28

1985 _____ -49.8 Mar __ -41.5 Feb __ 38 cm Apr 19-24 _____ 14.5 Jul __ 6.6 Jul _____ Oct 1

1986 _____ -50.7 Jan __ -41.8 Mar __ 22 cm Apr 9 - May 1 __ 11.3 Jul __ 4.3 Jul _____ Sep 21

1987 _____ -55.3 Feb __ -45.2 Feb __ 22 cm Jan 29-Feb 2 __ 16.6 Jun __ 6.0 Jul _____ Sep 26

1988 _____ -52.6 Jan __ -39.3 Jan __ 15 cm Feb 20-Mar 10__ 17.5 Jul __ 7.3 Jul _____ Oct 6

1989 _____ -52.4 Jan __ -42.5 Jan __ 22 cm Mar 5 - 9 ______ 11.9 Jul __ 4.2 Jul _____ Sep 28

1990 _____ -51.5 Jan __ -40.8 Feb __ 26 cm May 9-15 ______15.7 Jun__ 5.6 Jul _____ Oct 1

mean _____-50.8 _____ -41.0 ______ 22 cm Mar 27-Apr 5 ___14.8 _____ 5.6 Jul _____ Sep 29

---

ANALYSIS:



In general terms, there was not much change from the previous 30-year averages in the 1980s to 1990 -- but the onset of -20 C temperatures came a few days later with 1988 in particular having some difficulty settling into the winter chill.

Note: An unusual incursion of milder air on very strong northwest winds (gusting to 100 km/hr) took place on Jan. 24th 1982. Temperatures peaked at -9.6 C. In most winters readings higher than -20 are rare. No precip was noted within weeks of this date, except for trace amounts of snow which could have been just blowing snow. Very strong southerly winds occurred and some light snow fell earlier in the month (9th). This was during an unusually cold outbreak in eastern North America.

Then in Oct 1984, an unusual mild spell (near freezing) and heavy snow led to a 27 cm cover by Oct 14th (normal is about 5-10 cm). After increasing to 28 cm in mid-November, this pack continued to grow incrementally to 35 cm in late March and 38 cm in late April, with consistently very cold temperatures all through the period. April 1985 was particularly cold relative to normal values (mean -30.9). This perhaps shows us how a slight increase in the snow pack can really anchor colder air masses in these arctic source regions. Despite rather mild temperatures after mid-May, the snow pack melted off rather slowly and only disappeared finally by about June 28th (1985), about two weeks later than most years. It gave me the impression that a 60-80 cm snow pack might manage to last through an entire summer at that location, if the climate ever shifted in such a way as to produce that much snow. (Normally late June and all of July are snow free with 5-15 mm rainfalls, and then snow begins to fall again in August).

---

Moving towards the completion of the Eureka data set ... a reminder that min temp and coldest month can be in the Nov-Dec of the preceding year since this tracks winters rather than calendar years. Also the max snow depth can be before January of the stated year, but so far this has only been noted once (in 1974-75). The other data will always be in the calendar year quoted.

YEAR ___ Min temp _ coldest mo __ Max snow depth ____ Max temp _ warmest mo_ first -20 C

1991 ____ -50.7 Jan _ -40.1 Jan ___ 20 cm Apr 30-May 4 _ 16.1 Jul __ 6.4** Jul ___ Sept 29

1992 ____ -49.1 Jan _ -40.6 Jan ___ 21 cm Mar 21-Apr 8 __15.1 Jul __ 5.2 Jul _____Oct 3

1993 ____ -48.9 Mar _ -36.6 Mar ___20 cm May 12 - 15 ___16.7 Jul __ 7.3 Jul _____ Sept 28

1994 ____ -49.9 Mar _ -37.6 Mar ___08 cm Apr 22-May 9 _ 17.6 Jul __ 5.6 Jul _____ Oct 2

1995 ____ -52.0 Mar _ -39.2 Mar ___10 cm Mar 14-Apr 8 __18.6 Jul __ 7.3 Jul _____ Oct 3

1996 ____ -48.7 Feb _ -38.2 Mar ___16 cm Nov 27-28 ^ ___12.0 Jul __ 4.1 Jul _____Sept 14

1997 ____ -49.7 Feb _ -41.0 Feb ___19 cm Jan 15-29 ____ 15.6 Jun __ 5.6 Jul ____ Sept 23

1998 ____ -47.6 J F __-39.2 Jan ___ 19 cm May 18 ______ 17.8 Jul __ 6.9 Jul _____Oct 11*

1999 ____ -46.6 J M __-38.8 Jan ___ 21 cm May 14-15 ___ 16.5 Aug__ 7.0 Jul _____Oct 3

2000 ____ -50.2 Jan _ -41.4 Dec ___ 13 cm Apr 14-May 16_ 19.6 Jul __ 6.2 Jul _____Sept 28

mean ____ -49.3 ____ -39.3 _______ 17 cm Mar 28-Apr 9 _ 16.6 _____ 6.2 Jul _____ Sept 29

_________________________________________________________

Notes:

* September 1998 was much above normal in temperatures. There were few days even reaching -5 C and this milder trend continued for the first ten days of October. A more normal temperature regime was not reached before about late November although the entire winter season was relatively mild for the location, except for a near normal January of 1999. This was also a strong El Nino year and the warmest year on record at Toronto.

** Unfortunately the station reported no data from July 21 to 31 then resumed operation on August 1st. The 6.4 could have ended up between 5 and 8 given the normal range of temperatures in late July. Also the annual max of 16.1 could have been superseded. The first week of August 1991 was relatively mild there, so my guess is that the warmth of mid-July probably continued and the actual monthly mean might have been closer to 7.0.

^ This early peak snow depth was almost matched by 15 cm reported at times in March, April and May. There was unusually heavy snow in June 1996, 8.2 cm fell on June 9-10 at a time when the winter snow pack (not very large at any point) had mostly melted away. Another 3 cm fell on June 25. It is rare to see near-freezing (all day) temperatures and snowfall that late into June or at any point in July. But after a notably cold July there was more snow on July 23 and 27 (2-3 cm falls in each case). August continued with the colder than normal theme with a mean of only 1.0 (some milder Augusts are in the 3-5 range). There was a fall of 7.6 cm snow on August 20th which is also unusual as many Augusts see only small or trace amounts. This cover only lasted one day. Then the -20 C season began about two weeks earlier than most years.

ANALYSIS

While the decade of the 1990s to 2000 produced some variations, the background theme was slight warming. A new maximum of 19.6 was reached on July 29th, 2000, but the warmest month in the data set so far remained 7.5 in July 1962 (partially missing July 1991 may have been close to that and two more 7.3 values were added to the one produced in July 1988. Snow depth continued its slow decline, with winters of 1993-94 and 1994-95 particularly sparse (both maxed out at 8-10 cm). The timing of maximum snow depth changed only slightly from earlier averages and that was largely due to two anomalously early peaks, one in November 1995 and the next one in the following winter in January 1997. The onset of the -20 C season drifted back to near the end of September and on one occasion was two weeks late in arriving (Oct 1998).

=================================================================

YEAR ___ Min temp _ coldest mo __ Max snow depth ____ Max temp _ warmest mo_ first -20 C

2001 ____ -51.2 Feb __ -37.1 Feb __ 15 cm (two int) ** ___ 15.0 Jul __ 5.5 Jul _____Sept 24 ^

2002 ____ -48.4 Feb __ -40.6 Feb __ 21 cm Apr 30-May 5 _13.8 Jul __ 5.5 Aug ____ Oct 2

2003 ____ -46.1 Feb __ -38.1 Mar __ 20 cm Feb 7-15 ____ 20.0 Jul __ 7.6 Jul _____ Oct 4

2004 ____ -49.5 Mar __ -39.3 Mar __ 14 cm Apr 13-25 ____11.5 Jul __ 4.5 Jul _____ Sept 23

2005 ____ -50.2 Mar __ -36.0 Jan __ 29 cm Apr 16-17 ____ 15.2 Aug__7.2 Jul _____Oct 1

2006 ____ -46.8 Mar __ -35.5 Feb __20 cm^^Nov 30-Dec 1_15.3 Jul __ 6.4 Jul _____ Oct 5

2007 ____ -49.7 Mar __ -39.4 Mar __ 16 cm Apr 16-May 1 _ 20.7 Jul __ 7.9 Jul _____ Oct 3

2008 ____ -49.7 Mar __ -41.0 Jan __ 17 cm Feb 3 ________18.6 Jul __ 7.1 Jul _____ Oct 6

2009 ____ -50.1 Feb __ -38.6 F M __ 19 cm May 19-24 ___ 20.9 Jul __ 8.0 Jul _____ Oct 6

2010 ____ -45.4 Jan __ -34,7 Jan __ 30 cm Apr 23***_____ 18.5 Jun __ 6.7 Jul _____ Oct 2

mean ____ -48.7 _____ -38.0 ______20 cm Mar 20-Apr 1 __17.0 _____ 6.5 (Jul) ____ Oct 2

____________________________

** In 2001, two intervals had 15 cm snow cover, March 5-15 and May 6-16. The stats are averaged into the data means by duration of March 5 to May 16.

^ Rather like 1998, most of September was very mild and this early -20 was followed by more mild weather than is usually the case once -20 has been reached. The days from Sept 27th to October 4th were close to freezing at times and some snow melted. Another restart of the -20 C season occurred on October 10th without a return to mild conditions.

^^ An unusually heavy snowfall (10.8 cm on Nov 29, 2005) led to a temporary peak in snow depth of 20 cms. This settled to the 10-15 cm range within a week. Another maximum of 19 cms persisted through large parts of March and April but never broke the brief 20 cm earlier in the winter.

*** April 2010 was very different from most Aprils (which tend to be quite dry with stable snow packs near seasonal maximum). There was a total of 19 cms snow and some very mild temperatures in the -5 to -10 C range mid-month. The snow pack built up to its maximum then gradually settled back to 25 cm. One more snowfall brought it back to 29 cm on May 12th and that settled to 20-25 cm for a few weeks before it gradually melted in June.

note Feb 2006 may have been closer to -36 as one day of data missing and days on either side were cold.

---

ANALYSIS (2001-2010) ...

This decade continued a very slight temperature increase trend, adding about 1 C to the means of the previous decade in winter and less than 0.5 deg in summer. There was more variability perhaps, and some of the summers were notably warm, in particular 2009. The onset of winter (first -20 C) was further delayed to early October. There were several more episodes of very mild conditions in September and/or October, including the autumn of 2006. Snow pack maximum depths improved slightly over the minimum reached the previous decade, but began to show more of a bimodal tendency in this decade with several occasions of one "autumn" or early winter peak and a second similar spring or late winter peak. There was a noted tendency for snow depths to deflate after unusual mid-season snowfalls, possibly indicating greater water content in the snow than one might expect in this arctic desert climate.

We can now compare the 1981-2010 averages to the 1951-1980 averages previously calculated.

1951-80 _____ -50.4 __ -40.0 ____ 24 cm Mar 19 - May 2 _____ 15.5 ___ 5.5 _____ Sep 25

1981-2010 ___ -49.6 __ -39.4 ____ 22 cm Mar 25 - Apr 5 _____ 16.1 ___ 6.1 _____ Sep 30

The frequency of various extremes compares to the first set as follows ...

1948-80 ___ Winter min _______________ 1981-2010 ___ Winter min __________ Total (63 winters)

__ 2.5 Dec, 8.5 Jan, 13.0 Feb, 9.0 Mar ____ 0.0 Dec, 9.0 Jan, 9.5 Feb, 11.5 Mar ___ 2.5 Dec, 17.5 Jan, 22.5 Feb, 20.5 Mar

1948-80 ___ Coldest month ____________ 1981-2010 ___ Coldest month ________Total (63 winters)

__ 5 Dec _ 6 Jan _ 12 Feb _ 10 Mar ______ 1.0 Dec, 9.0 Jan, 10.5 Feb, 9.5 Mar ___ 6.0 Dec, 15.0 Jan, 22.5 Feb, 19.5 Mar

1948-80 ___ Summer max ______________ 1981-2010 __ Summer max _________ Total (63 summers)

____ 4 Jun ___ 23 Jul ___ 6 Aug _________ 5 Jun __ 23 Jul __ 2 Aug ___________ 9 Jun __ 46 Jul __ 8 Aug

1948-80 ___ Warmest Months ___________ 1981-2010 __ Warmest Months ______ Total (63 summers)

____ 0.0 Jun ___ 30.5 Jul ___ 2.5 Aug _____ 0 Jun ___ 29 Jul ___ 1 Aug _________ 0 Jun __ 59.5 Jul __ 3.5 Aug

There have not been large shifts in these distributions, the coldest part of winter continues to be mid-January to early March, and

the warmest part of summer late June to early August. The years that have their warmest day outside of July usually hit a day within a week of July, mid-June to mid-August is the extreme range (compared to mid-May to late September in southern Canada).

====================================================

(2011-2019 stats)

YEAR ___ Min temp _ coldest mo __ Max snow depth ___ Max temp _ warmest mo_ first -20 C

2011 ____ -49.5 Feb __ -38.8 Feb __ 34 cm Jan 2 - 3 ____ 20.0 Jul __ 9.8 Jul _____ Sept 28

2012 ____ -50.4 Mar __ -37.2 Mar __ 30 cm Apr 2 -11 ____ 17.9 Jul __ 8.7 Jul _____ Oct 8

2013 ____ -51.5 Mar __ -42.3 Feb __ 20 cm Mar 27-Apr 6__12.8 Jul __4.5 Jul _____ Oct 4

2014 ____ -50.4 Feb __ -39.1 Feb __ 29 cm Mar 23-Apr 3__14.6 Aug__5.9 Jul _____ Oct 3

2015 ____ -49.2 Feb __ -36.9 Mar __ 12 cm Jan 23-25 ____20.2 Jul __ 9.6 Jul _____ Sept 28

2016 ____ -47.8 Dec __ -37.4 Dec __ 15 cm Apr 6-May 17_ 18.1 Jul __ 8.2*Jul _____ Oct 9

2017 ____ -50.7 Mar __ -34.8 Mar __ 22 cm May 24 ______13.8 Jul __ 5.5 Jul _____ Sept 26

2018 ____ -46.3 Mar __ -38.0 Mar __ 14 cm May 9-10 ____ 14.5 Jun __4.5^Jul _____ Oct 1

2019 ____ -46.5 Mar __ -36.5 Feb __ 26 cm Jan 1*** _____ 19.0 Jul __ 9.7^Jul _____ Oct 17

2020 ____ -49.0 on Jan 3 is coldest so far ... only 5 cm snow cover all of Jan 1-14.

mean ____ -49.2 _____ -37.9 ______ 22 cm Mar 14 - 22 __ 16.8 _____ 7.2 Jul _____ Oct 4

_____________________________________________________________

* Some temp data missing July 1-2, mins are shown but not maxes, looked colder than the monthly mean of 8.4 so that is reduced here to 8.2 (est 3.5 1-2).

^ Some temp data missing July 1-3, mins are available, and this time it looked a bit milder than the cold monthly mean of 4.3 so I adjusted up to 4.5 (Aug was complete and also 4.3).

^ Also the next July has three missing days 20-22 July, these may have been fairly warm as per Eureka (A) which is inland (opened later in the study period) and runs a bit warmer in warm summer spells (probably a sea breeze effect closer to the fjord where Eureka climate station sits). I raised this data from 9.4 as reported to 9.7. There is some chance that the 19.0 max was broken then also (but the airport station while warmer than 19 in the missing days had its max on the same day as the 19.0). Considering the location and length of data period, I was fairly pleased with the continuity of data in general; as with other studies I am doing, the most recent years have more frequent missing days. Not sure if this is due to insufficient time for quality control to work through the data sets, or some kind of staffing issue that is getting worse with time, but it seems to affect a lot of different Canadian data sets.

*** This is the only example I saw in all data of a large one-day shift in snow depth that might be attributable to winds. No measurable snow was reported, the depths on both the previous and next day were under 12 cm, but a moderate southeast wind was reported. The other explanation might be a coding or data entry error. If not for this 26 cm reading on New Years Day then the maximum snow depth occurred on March 28th (17 cms).

_____________________________

ANALYSIS of 2011-19 data

Although 2013 and 2014 were rather cold, this past nine years has seen mostly continuation of the slow warming trends of previous decades. There were at least three anomalously warm early winter periods (September into early October) in 2012, 2016 and 2019. This current winter 2019-20 started out rather feeble for cold, but converged on normal through December and has been quite cold in the first half of January (average so far is -40.4). The snow pack is currently very sparse, only 5 cm on the ground.

______________________________

SUMMARY of this study

Eureka represents a climate very close to the Greenland (and lesser Ellesmere Island-Devon Island-Axel Heiberg Island) ice caps and appears to be receiving more frequent incursions of milder air masses in winter, although not to the extent that the climate is radically different from the mid-20th century. These incursions do not happen every winter, or if they do happen in a given winter, they might only take place in say November or March, and not several different times. This seems to be the main reason why both average and extreme winter temperatures are gradually moderating, but make no mistake, this is still a very harsh arctic climate with full expectation of seeing -45 C days and -35 C months, most likely from January to March. A few anomalous events were noted throughout but this is a very predictable climate with long stretches of similar weather at various times of year. The summers also appear to be warming very slightly, and the onset of them has moved generally from late June into mid-June. A typical summer will not end suddenly but will fade out through August with a return of some snow and freezing daytime temperatures by late August. This can sometimes be muted and delayed well into September in a persistent southerly air flow bringing in saturated air from the Davis Sea (west of Greenland) that has temperatures near 2 or 3 C and dew points near 1 C. A cold drizzle falls from low clouds in this air flow, and it probably deposits wet snow on higher hills and the surrounding ice fields. The frequency of this sort of extended late summer appears to be rising in recent decades (from perhaps less than once a decade to 3-4 times now). Spring in most years seems to be a case where milder air masses slowly work their way into the region and sit over the decaying snow pack until it has all melted, then temperatures rise from around 5 C to 10-15 C with the bare ground exposed. But it does not appear that there is much of a shift in the weather itself after the melt is finished. Warmth depends mainly on hours of sunshine rather than any sort of air mass arrival.

This is a precarious climate which could easily tilt to some other set of conditions, if for example winter snowfall increased in the region. It has seldom been much more than 30-40 cms in any recent winter. If for any reason heavier snow begins to fall more frequently, that could quite possibly stick around long enough to last through the brief summers. If on the other hand snow cover diminishes further, then summer could lengthen to something like late May to early September. Since Eureka is on a narrow inlet which is itself an extension of a relatively narrow channel between two large islands (Ellesmere and Axel Heiberg are roughly equivalent to Great Britain and Ireland in size) the oceanic influence (whether of open or frozen seas) is not large but it must play some role, so changes in ice cover might mean changes in precipitation. In what is almost a desert like rainfall profile, any increase would have significant effects on the environment. There seems little potential for precipitation to decrease at this location.

(In a reply to a comment I mentioned that Eureka changed name to "Eureka climate" in 2016 but is essentially the same location, the instruments were moved within a small area for some unknown administrative reason. Meanwhile another station has opened up from about the same time, Eureka A (airport) which appears to be somewhat higher and inland a few kms, located to the southeast of the data collection site used here. Summer temperatures are 1-2 deg higher showing that the fjord setting is still enough of a maritime exposure to generate a sea breeze (off very cold water with ice floes often present). I also mentioned to somebody chatting about Eureka being so far north that it is on an island about the size of GB and some distance inland along a fjord that connects to a narrow channel separating Ellesmere Island from Axel Heiberg Island, which is almost the size of Ireland. The channel is considerably narrower than the Irish Sea, about 5 km wide, and so the two islands might be considered more like one large island with a marine inlet complex.

This climate fascinates me being both harsh yet tolerable enough for human habitation without the need for the extraordinary measures that they need to take at Vostok station or the South Pole.


Full data set summary (72yrs) at Eureka, Nunavut - Canada


1948-2019 ___ Winter min ______ 3.5 Dec, 17.5 Jan, 25.5 Feb, 25.5 Mar

1948-2019 ___ Coldest month ___ 7.0 Dec, 15.0 Jan, 26.5 Feb, 23.5 Mar

1948-2019 ___ Summer max ____ 10 Jun __ 53 Jul __ 9 Aug

1948-2019 ___ Warmest Months __ 0 Jun __ 68.5 Jul __ 3.5 Aug

Gaoth Laidir

Great work and analysis. What a place to visit.

M.T. Cranium

I have been as far north as central Yukon and flown over Greenland and Baffin Island in clear weather, that's the extent of my travels in this region. Have experienced -40 cold a few times even in Ontario, so these -50 readings are not that far into the realm of mystery. And we have more snow on the ground where I am now than most of these places have seen in any recent winter. It won't still be here in May though (I hope).