Irish Weather Statistics

echat wrote: »

Thanks for reply and link. If climate change results in an earlier start to the warming of the land and sea, will that tend to pull the warmest days back into July?

It's possible but I'm a skeptic of climate change (not a denier nor believer). It's a funny quirk in Ireland how the warmest day on record took place on 26th June 1887 with a maximum of 33.3c at Kilkenny Castle whilst the warmest July temperature on record here is 1 degree less than that of 32.3c at Elphin, Co. Roscommon on 19th July 2006. The warmest day of the year just all depends on how patterns go down. There are years where the highest temperature of the year was recorded in September like 1906 and 1998.

I would like to do January 1881 - the month of a great blizzard that struck the UK and Ireland's all-time lowest minimum temperature - but ECA&D's site is still recovering from its security issues which is where the temperature recordings for Phoenix Park and Valentia Observatory would come from for the post I would make on it.

For now, I am doing the blizzard of February 1978. This blizzard tends to get overshadowed by those of 1917, 1933 (which itself tends to not get much light nowadays), 1947, 1963 and 1982. I think a reason being is the fact that it didn't affect the east coast of Ireland much. The snow was mainly around southern regions of Ireland.

I will start off with a brief summary of the weather during February 1978. February 1978 was the coldest February since 1969 with mean temperatures as low as 3.2c at Glenties, Co. Donegal and Dunsany, Co. Meath, around 1 to 1.5c below average using the 1981-2010 averages. To put this into perspective, Dunsany's mean for February 1978 equals that of February 2018 at the station. The reason for February 1978's cold mean temperatures was down to the cold spell from the 8th-19th which was dominated by easterly winds of continental origin. High pressure built over Scandinavia linking up with the high over Greenland to form one monster block. Low pressure tried to invade from the Atlantic a couple of times but were forced to track southwards and pass close by the south coasts courtesy of this anticyclonic block up to the north. These depressions led to heavy falls of snow accompanied by the bitter strong easterly winds to southern and some midland or eastern regions. Roche's Point had nearly 5 inches of precipitation (including 39.5mm on the 11th and 38.7mm on the 18th) during the cold spell as a consequence of these depressions whilst parts of the north, west and other midlands received very little but still very cold nevertheless.

The first week was westerly based but not all that mild with temperatures relatively below average in spite of a lack of severe air frost whilst the last week of the month brought in southwesterly winds resulting in a warming trend (in comparison to February 2018 which went the opposite way) and thus why the February 1978 mean temperatures weren't as severely cold as they could have been.

The air minimum temperature for February 1978 at Irish stations that I know of was -10.0c at Glenties on the 13th whilst the grass minimum temperature plunged to -16.0c at the same station on the 12th. Mean temperatures for the period 11th-20th February 1978 were -0.3c and -0.5c at Carlow (Oak Park) and Glenties respectively. The lowest the UK got to was -22.0c at Keith (Grampians) on the 19th/20th, the lowest since 1963.

Some notable low maximum temperatures include -0.8c at Cork Airport on the 12th and 0.8c on the 19th, 0.3c at Carlow (Oak Park) on the 12th, 0.1c at Kilkenny on the 12th, 0.6c at Birr on the 11th and 0.4c on the 12th.

On to the blizzard I go. On the 18th and 19th February 1978, an area of low pressure slid just to the southwest of Ireland with the cold being well established by then over the country. Easterly winds gusted to nearly 70 mph at Malin Head on the 18th with a maximum 10-minute wind speed of 45 mph on the same day. The precipitation increasingly turned to heavy snowfall as it hit the cold air over the Irish and British lands. The strong winds led to large snow drifts of up to 20 ft in the southwest of the UK. The weather front carrying the snow was expected to move right across the south and continue to move eastwards into the midlands of the UK, but stalled over the southwest bringing depths to these regions unknown to man. Over 34cm of snow with 24 ft drifts were reported at Exeter Airport and a depth of 26cm at Cork Airport was recorded. To this day, this is Cork Airport's greatest snow depth on record. Enormous drifts on the moors in England blocked scores of roads, paralysing the transport network. Power lines were brought down and for three days many parts of Devon had no electricity or running water. Supplies of food and water were flown into the worst hit areas by helicopter. Not much is known in regards to the blizzard in Ireland (I couldn't even find a picture taken in Ireland of the blizzard) but it was one of the worst blizzards ever to hit the south of Ireland and the southwest of the UK.

Fun fact: February 2018 was the 40th anniversary of February 1978 and we got a blizzard in 2018 (albeit on 1st/2nd March) too.

So Corkians, you should be dreaming of a February 1978 repeat.

The beginnings of the cold spell, 8th February 1978.





A low that developed out to the west on the 11th brought a snow depth of 6cm at Shannon Airport, its greatest snow depth on record to this day.



The period of the February 1978 blizzard.





All data comes from Met Éireann and the UK Met Office.

http://www.bbc.co.uk/devon/content/articles/2008/02/21/blizzards_1978_archive_video_feature.shtml

This was a last minute choice since I didn't really prepare for today's historical post but this is the storm of 23rd-26th September 2012.

What happened was that a deep area of low pressure with a centre of 973mb approached from the south of England and pushed northwards during the evening of the 23rd. This lingered in the central and northern swave of the UK as well as affecting northern and east parts of Ireland nearly all day on the 24th with persistent heavy rainfall in gusty easterly winds, later veering to northwesterly to northerlies. Further heavy rainfall occurred over the same places on the 25th before finally starting to clear southeastwards into south England during the afternoon of the 26th. This was the deepest September storm since 1981 and it was so unusual to be seeing a low as deep as this in September especially considering that much of September 2012 up to that point was sunny and dry. This was a reminder that Mother Nature wasn't done with us just yet in delivering a poor to atrocious period of weather that begun in April that year and would only end in the third to last week of May 2013.

I remember the event so well and Monday 24th September 2012 remains one of the wettest September days I've experienced with Monday 6th September 2010. Like the 1st May 2012 and 7th/8th June 2012, the skies for the 24th September 2012 were so dark and it looked like nightfall all day long under the ongoing persistent rainfall. Not a peak of sunshine or daylight! Like the 6th September 2010 though, I absolutely loved it and wouldn't mind a repeat. It was one of the few days I liked in the god awful year of 2012. I love the extremes ok! Again silly me did not take any videos or pics just like I didn't in 2010! :mad:

Rainfall totals for Irish stations during the period.

Station|Rainfall total (mm)|Date
Ardee (Boharnamoe)|33.5|24th
Casement Aerodrome|36.6|24th
Celbridge|26.3|24th
Dublin Airport|37.9|24th
Dunsany|22.2|24th
Malahide Castle|70.5|24th
|18.2|25th
M. Sally Gap|49.3|24th
|30.5|25th
Glenbride Lodge|45.1|25th
Glenmacnass|18.1|26th
Naas C.B.S.|24.5|24th
Ringsend|43.9|24th
Phoenix Park|32.6|24th


Malahide Castle's daily total of 70.5mm on the 24th was over 2/3 of its September 2012 monthly rainfall total of 106.8mm - its wettest September since 1975. In contrast, Ballineen, Co. Cork recorded only 5.7mm of rainfall throughout September 2012 making it the driest September here on record since its records began in 1994. All parts of Cork received under 30% of their average September rainfall whilst places like Malahide Castle had up to 181% of their September rainfall and the main reason for this was this event or storm of the period 23rd-26th.

It wasn't only the rain that was notable, it was also how cold for the time of year it was. According to the BBC, several Met Office stations recorded their coldest September day on record on the 24th. They include Glenanne (Armagh), Altnahinch (Antrim), and Lough Fea (Tyrone), all in Northern Ireland. Slieve Bloom Mts (Nealstown) recorded a maximum of 9.2c on the 24th whilst Dublin Airport recorded a max of 10.4c under the heavy rain on the same day.

Data comes from Met Éireann.

Impacts for the UK from the UK Met Office:

An unusually vigorous area of low pressure brought very unsettled weather to most parts from the 23rd to the 26th, giving particularly high rainfall totals (most notably 130 mm at Ravensworth, North Yorkshire, over a 3-day period) and some strong winds. Prolonged heavy rainfall across SW England overnight 23rd / 24th resulted in some transport disruption, with localised flooding of roads, and main rail routes closed for a time. During the 24th, the heavy rain moved north, bringing disruption to road and rail journeys in the West Midlands, North Wales and northern England. On the 25th, strong winds in eastern Scotland resulted in fallen trees, power cuts, and restrictions on road bridges. Rail services on the East Coast mainline and roads and properties in NE England were further affected by flooding. By the 26th, there were concerns about the rising levels of rivers across northern England, such as the River Ouse at York, and also across north Wales. Around 600 homes and businesses were reported to have been flooded across England and Wales since the 23rd.

Satellite on 24th September 2012, the main day of the event.





Event thread:

https://www.boards.ie/vbulletin/showthread.php?t=2056759625

echat wrote: »

Do they make these presentations available online afterwards? https://www.irishmetsociety.org/programme/june-public-lecture-details

Not sure, I don't think so but I really do not know so I can't answer that sorry for certain.

Exceptionally dry June for the south of the UK, not just the south and east of Ireland. Most parts of England have had under 10% of their average June rainfall and is likely to be the driest June since 1925 if not THE driest June on record for some.

https://twitter.com/metofficenews/status/1009069777170640896

I have done posts on a lot of the heatwaves that Ireland has recorded but I have not done the warm spell of late August and early September 1991. There is the traditional Back to School week with fine weather after a poor Summer in Ireland as we all know and 1991 certainly fit that category. It was the best possible Back to School week Ireland could have really.

Summer 1991 was largely mixed. June was a very cold, wet and dull month whilst July was quite dull but warm and dry. August tended to be on the dull side too but not as significantly so as the preceding few months. It was a warm and dry August too. We would most certainly not turn down a month like August 1991 today due to how many poor Augusts we have had since 2006. The best spell of the entire Summer and year for warm, settled and sunny weather (May 1991 was exceptionally dry but mainly dull) occurred during the last week of August and first week of September. Perfect timing for going back to school! I would have not liked to be a student in 1991.

To start off, how did this spell come about? High pressure built just to the east of England at the end of August keeping the Atlantic depressions out at bay and dragging in a warm southeasterly wind. This became a very stubborn area of high pressure and retrogressed up to the north of Ireland during early September with a maximum pressure of 1034.5hPa at Malin Head on September 3rd. Ardfert, Co. Kerry recorded 26.8c on August 29th whilst Belmullet reached 26.7c on August 30th. These were to be beaten in early September with temperatures rising as high as 28.4c at Valentia Observatory on September 5th, its highest September temperature on record and Ireland's highest September temperature since 1906. This was recorded in abundant sunshine with much of the fortnight of September 1991 being very sunny, dry and warm whilst the second half was much cooler and became very unsettled. For instance, Cork Airport recorded 40.7mm on September 27th.

Other notable recordings include 26.2c at Fermoy (Moore Park) on September 5th, 26.4c at Roche's Point on September 2nd, 26.1c at Shannon Airport on September 5th, 27.6c at Ardfert on September 5th, 27.0c at Mooncoin on September 3rd, 26.6c at Kilkenny on September 3rd & 5th and 26.3c at Dungarvan on September 2nd.









All data comes from Met Éireann.

pauldry wrote: »

heres a difficult one

There seems to be a constant NW wind in most Summers when there is no heatwaves

Im wondering is there or am i imagining it

Those bad Summers of 2007 -12 were plagued with NW winds in Sligo

I thought SW was our prevailing but NW seems to outnumber it

It's always tricky to pin down exactly the prevailed wind direction for a season because Ireland is so changeable and not to mention that each year, it tends to be unique from the other in multiple different ways whether it's the length of warm spells, the timing of warm spells, the intensity of the rainfall, number of thunderstorms and so on.

I have the NOAA Summer reanalyses with me here and going by their 500mb height anomaly maps (though this isn't an accurate way of doing so), the wind direction would tend to be from:

2017: Westerly
2016: Southwesterly
2015: Westerly
2014: Northeasterly
2013: Southeasterly
2012: Northeasterly
2011: Northwesterly
2010: Northeasterly
2009: Southwesterly
2008: Westerly
2007: Northeasterly
2006: Southerly
2005: Southerly
2004: Southwesterly
2003: Southerly
2002: Northwesterly
2001: Southwesterly

Going by these charts, it looks like there's been two northwesterly dominated Summers and those are 2002 and 2011. Not surprisingly enough, both were very dull Summers as to be expected from northwesterlies in Summer. 2011 was the dullest Summer on record at Knock Airport ('til it was beaten by 2016) and 2002 was the dullest Summer in the east since 1986. I think a good reason why you would think that way is because of the fact that you're often underneath a trough of below average 500mb heights which defines the zonal pattern that makes Ireland, Ireland. Sure, there have been some northwesterly patterns in Summers a lot of times, I've just named two of them. Another example is 1981 which was a dull, cool and dry season.

I do find it odd how (going by you here) Summer 2007 would be a northwesterly Summer for you because you in the northwest was the warmest out of the entire country in 2007 due to the distribution of the below average heights centred over England and Wales than to the northwest of Ireland which brought in a northeasterly airstream. This resulted in cool conditions to the east of Ireland and much of the UK too with some very notable rainstorms.

It's an interesting discussion I have to say.

Whilst generating this graph, I just noticed that Dublin Airport has not had a July with a monthly sunshine total of 250 hours or more since 1989. Even July 1990, 2006 and 2013 didn't reach 250 hours or more at the station.

Interesting how July 1971 is the second sunniest July at the station. Certainly not a month OR Summer that sticks out in my mind.

A July with 200 hours or more is a rare occasion too. July 2013 was the last occurrence. July 2014 was pleasantly sunny though.

In response to yesterday saying how dull Summer 2002 was, you can see July 2002 being a very dull month at Dublin Airport on the graph too.

Leo Bonacina developed a snowfall catalog as a guidance to looking at how snowy each historical Winter was for the UK. He used multiple sources to give his assessments and information on snowfalls during the seasons in his catalog. The problem is that this can be quite a subjective task to do and regional variation would matter a lot.

It will be a difficult task but I would like to do an Irish version of this as far back as possible (most certainly won't be as many Winters as the UK one due to the lack of data and sources on Irish snowfalls). With this, I will be posting my assessments possibly numerous times and asking for your opinions.

http://www.neforum2.co.uk/ferryhillweather/bonacina.html

Two higher minimums I just found than the 18.1c at Shannon Airport on 22nd July 2014.

18.5c and 18.2c at Dublin (Merrion Square) on August 15th and 21st 1997 respectively.





Data comes from Met Éireann.