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03-12-2018, 20:19   #1
M.T. Cranium
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Location: across from the neighbours
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9th annual winter forecast contest 2018-2019

WELCOME to the 9th Annual Winter Forecast Contest. The rules will be similar to past years ...

The deadline will give you a chance to peer into the first week of December with some idea what's going on as the season starts. In weather circles, winter is December, January and February, and that will be the basis of our contest. Read the rules carefully and feel free to enter any time before the deadline ...

Entries accepted until 1500h Thursday 6 December, have moved this up ahead of an expected windstorm on Thursday night so that its maximum gust values are not known to any late entrants.

This contest was already opened up with the December forecast thread, and about 20 entries have been received in that thread. But we want to keep the tracking separate and invite in any Boards members who didn't see the original announcement. You have a few days yet, any forecasters who already entered can change any of their posted forecasts either here or back in the December thread. I will bring the table of entries over here on Friday 7th and add in any new forecasts posted here.

The top scores in past years were close to 75/100 to give you some idea of what the standard is. Here are the rules, look at the end of this post for a template that you can use to enter. I will make an effort to review all entries and contact anyone who has an incomplete entry. It's up to you to be familiar with the rules in each question.

(1) For each month Dec Jan Feb, predict the "IMT" which is the Irish Mean Temperature, a statistic developed on this forum by Deep Easterly, and the average of five stations in central inland locations (Shannon, Oak Park, Mullingar, Casement, Claremorris). For newbies, this is the average of daily highs and lows. Over recent 30-year periods, the means have been around 5.4 in Dec, 5.3 in Jan and 5.2 in Feb. Very mild months would run around 8-9 C and very cold ones a little below freezing (Dec 2010 was -0.4). These forecasts generate 5 points each, and the seasonal average, which you don't need to calculate (I do that from your entries) counts for 15 points.

(2) For each month Dec Jan Feb, predict the monthly precipitation as a percentage of normal values. This is calculated as in our monthly forecast contest, from records taken at eleven stations that report in the Met Eireann Monthly Summary. Those are the five mentioned above plus Valentia, Cork, Johnstown Castle, Belmullet, Ballyhaise and Malin Head. Note that Dublin is not included. Values under 50% are considered exceptionally dry and above 200% exceptionally wet (for your guidance). The scoring for these three forecasts and the seasonal average which again you don't need to enter, will also be 5,5,5 and 15 points.

(3) For all the reporting stations of Met Eireann, as reported in their Monthly Summary, predict the seasonal highest and lowest temperatures. This will apply only to dates from 1 Dec to 28 Feb for the max, but can apply to dates both before and after the winter for the min (up to 15 April when the contest results are declared). The max in the past three winters has been close to 15 and the min during the first contest was about -16 but then more like -6 in the second contest, -8 winter of 2012-13, and similar values the past two winters. I would guess the long-term average for the winter minimum is around -8 to perhaps -10. These two predictions are worth ten points each.

(4) Predict the seasonal snowfall (in cms) at Casement. This will run from the first measurable snowfall (your forecast should include anything already reported if it does snow in November, check this thread and elsewhere for updates on that) to 15 April (anything after that won't count as the contest is over on 15 April). These daily snowfall values (if they occur) are measured at hourly intervals and summed, which means the snow depth at any point might not be quite as much as the snowfall amount. However, amounts vary a lot from season to season. In the first contest winter 2010-11, there was about 50 or 60 cms but then we used a stat from Boards member "Danno" in Laois who had about 30 cms. In 2011-12, I believe there was almost zero accumulation and our lowest contest guess had the highest score. This was similar to the past four winters when most of the field guessed higher than what actually fell at Casement (something like 7 cm in 2012-13 and 3 cm in 2013-14 and 2 cm in 2014-15, 3 cm in 2015-16, almost nothing in 2016-17 and a moderate amount last winter compared to the heavy dumpings that occurred in Dublin and Wexford). This part is worth ten points.

(5) Finally, predict the highest wind gust in knots at any reporting station in Ireland as per the Met Eireann Monthly Summary, but note that in this case, the period is only the three winter months -- strong winds back in November or in March or early April won't count, the gust has to be between 1 Dec and 28 Feb. Knots are almost double km/hr and about 1.15 times mph. Values between 70 and 100 knots are most likely to verify from climatology, the extreme range would be about 50 to 120 for this statistic. This part is also worth ten points.

Note: All scores are based on rank order, not absolute differences from prediction to actual values. This equalizes the various sections of the contest and distributes the scores evenly. Once we establish the number of entries, I will update this scoring system, but basically, 10% of the entries get top scores in each category and then on down, with any odd numbers left over getting the zero scores. Where it's 10 points, the gradations are 10,9,8,7,6,5,4,3,2,1,0 and where 5 points, half of those values, where 15 we will give equal numbers of scores, and let you know later how many will share each score (based on number of entries).

So, here's the template, once you understand what to predict, just change all the letters here to number values and block copy, submit along with your comments etc. You can edit your post without notifying me at any time up to whenever you see the entries cut off announced and a table appearing in the thread. I don't work on that until the cut off, so edit at will, I won't know except for the forum software making a note of it.

TEMPLATE FOR ENTRIES

DEC-IMT
JAN-IMT
FEB-IMT
(I work out the average for you)

DEC-PRC
JAN-PRC
FEB-PRC
(I work out the average for you)

MAX TEMP C (must be in Dec, Jan or Feb)

MIN TEMP C (can be up to 15 April)

SNOW cms (total to 15 April, zero so far)

GUST kts

(all temps can have one decimal place, prc % to nearest whole number, snow can also have one decimal place, gust to nearest whole number)

-------------------------------------------------------------

Good luck !!

(previous entrants in Dec thread, no action required)

Last edited by M.T. Cranium; 04-12-2018 at 07:42. Reason: deadline has been moved forward to be earlier than predicted windy event
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06-12-2018, 10:33   #2
Rebelbrowser
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Join Date: Jan 2010
Location: Cork
Posts: 1,308
DEC-IMT 6.2
JAN-IMT 4.9
FEB-IMT 5.9


DEC-PRC 111
JAN-PRC 82
FEB-PRC 73


MAX TEMP C 15.2

MIN TEMP C -6.3

SNOW cms 2cm

GUST kts 71
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06-12-2018, 12:42   #3
sunflower3
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Join Date: Jan 2010
Posts: 103
DEC-IMT 6.0
JAN-IMT 4.5
FEB-IMT 4.8


DEC-PRC 105
JAN-PRC 110
FEB-PRC 85


MAX TEMP C 16.0

MIN TEMP C -7.0

SNOW cms 4cm

GUST 65 kts
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06-12-2018, 22:17   #4
M.T. Cranium
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Join Date: Apr 2007
Location: across from the neighbours
Posts: 9,531
Table of forecasts for winter forecast contest 2018-19


Forecasts are listed in order of winter mean temp (IMT) -- the winter mean temp and prc values are calculated from your monthly forecasts. If your DEC max or min are more extreme than what you mentioned for rest of winter, the DEC values enter the contest. Twenty forecasts were posted in the December contest thread, and two more here, which have been incorporated into the table ...

the contest is now closed to further entries due to impending windy conditions that might provide real-time advantages (if you think this is going to be as windy as it gets, I don't) ...


FORECASTER _________ IMT ______________ PRC _________ MAX __ MIN ___SNOW (cm)_MAX GUST (kts)
________________________________________________________________________________________

pauldry ___________ 6.7 5.4 5.2 5.77 __ 135 100 089 108 __ 15.2 _--17.7 __ 20.0 ____ 75

Rebelbrowser ______ 6.2 4.9 5.9 5.67 __ 111 082 073 089 __ 15.2 __--6.3 ___ 2.0 ____ 71

Tae laidir __________5.9 4.6 5.5 5.33 __ 138 115 120 124 __ 14.8 __--8.8 ___ 8.0 ____ 78

___ NormaL _______ 5.4 5.3 5.2 5.30 __ 100 100 100 100 __ 15.5 __--9.0 __ 12.0 ____ 80

Bsal ______________5.4 5.2 5.2 5.27 __ 125 099 105 110 __ 15.0 __--6.5 __ 10.0 ____ 79

John mac __________5.4 5.0 5.4 5.27 __ 120 102 090 104 __ 15.0 __--8.0 __ 13.0 ____ 70

sunflower3 ________ 6.0 4.5 4.8 5.10 __ 105 110 085 100 __ 16.0 __--7.0 ___ 4.0 ____ 65

sryanbruen ________ 5.6 4.9 4.6 5.03 __ 110 085 110 102 __ 15.3 __--7.2 ___ 3.0 ____ 84

dacogawa _________ 5.6 4.6 4.8 5.00 __ 132 090 110 111 __ 15.9 __--9.4 __ 41.0 ____ 81

rikand ____________ 5.5 4.5 5.0 5.00 ___090 090 090 090 __ 16.0 _--11.1 __ 30.0 ____ 80

Joe Public __________6.1 3.9 4.8 4.93 __ 127 110 104 114 __ 14.9 __--8.9 __ 23.0 ____ 76

Adam240610 _______ 6.0 4.4 4.4 4.93 __ 124 100 095 106 __ 15.0 __--8.1 ___ 4.0 ____ 76


___ Consensus ______5.8 4.5 4.5 4.93 __ 111 093 093 099 __ 15.1 __ --8.9 __ 12.0 ____ 76

mickger844posts ____ 5.6 4.7 4.5 4.93 __ 100 090 110 100 __ 16.3 __--5.2 __ 10.0 ____ 69

200motels _________ 5.7 4.3 4.6 4.87 __ 110 109 095 105 __ 15.9 __--8.9 ___ 8.0 ____ 70

MrSkinner _________ 6.0 4.4, 4.2 4.87 __ 090 090 090 090 __ 14.3 __--6.8 __ 20.0 ____ 68

Artane2002 ________ 6.0 4.0 4.5 4.83 __ 120 085 090 098 __ 14.7 __--8.1 __ 12.0 ____ 70

M.T. Cranium _______5.9 3.0 5.5 4.80 __ 120 090 090 100 __ 15.0 _--12.0 __ 18.0 ____ 84

JCX BXC ___________5.5 4.6 4.2 4.77 __ 090 085 110 095 __ 14.5 _--10.2 __ 13.0 ____ 80

DOCARCH _________ 5.7 4.8 3.2 4.57 __ 135 105 075 105 __ 16.2 __--9.6 __ 23.0 ____ 79

Rameire ___________5.2 4.3 4.0 4.50 __ 095 095 100 097 __ 13.5 __--8.6 ___ 9.0 ____ 73

sdanseo ___________5.8 3.2 2.1 3.70 __ 112 103 085 100 __ 14.6 _--13.8 __ 29.0 ____ 81

Bazlers ____________5.0 2.1 4.2 3.70 __ 110 080 090 093 __ 14.0 _--13.5 __ 27.0 ____ 78

BLIZZARD7 ________ 4.7 1.1 2.7 2.83 __ 120 090 120 110 __ 15.5 _--18.3 __ 37.0 ____ 73

_________________________________________________________________________


Consensus is the median value for all forecasts, with 22 of them, the median is average of 11th and 12th ranked values so in some cases Consensus is not equal to any individual forecast. The consensus IMT for the season was going to be the mean of the three consensus values but happens to be also the median of our seasonal averages. The mean PRC for the season is the mean of the three consensus values, 99 per cent. The median of our seasonal values is 101 per cent.

Seasonal winter forecast based on group consensus and spread:

The 22 participants foresee a slightly colder winter than normal, with all of the negative departures likely to fall in January and February after a slightly milder than average December. The average for Jan-Feb is expected to be about 0.7 deg below normal, with some going as low as 3.5 degrees below. A minority of the forecasters believe the full winter season will stay mild, as most think December will be, generally 0.5 above normal.

The consensus calls for a near normal range of temperatures from -9 to 15 degrees, and on the maximum there is only a small spread of opinion. As it has already reached 14.2 in early December, few think it will get much warmer but when they do, they mention February as the more likely month (some mentioned January). On the coldest temperature, there is a wide spread of opinion. Some believe we will not see colder readings than we already had in November (minimum -5.2 is the highest value in the contest). About one-third think it could get down below -12 C. These are the same forecasters calling for heavier snowfall (at Casement, the contest validation site). Here, the range is quite large too, from 2 cms to 41 cms. The snowfall season for the contest includes March and early April so this would not all necessarily have to fall in the winter months. As far as strong winds are concerned, the spread of forecasts is fairly tight and the consensus is a maximum gust of 76 knots, while the range is from 65 to 84 knots.

Most of the forecasters believe December will be a little wetter than normal, while January and February are likely to be on the dry side of normal (which correlates well with their colder than average calls). The ranges are not extreme, with few individual forecasts outside the range of 80 to 120 per cent of normal for any month. The range for the season is from 89% to 124% of normal precipitation, and the consensus is very close to normal.
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