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04-08-2019, 17:49   #991
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Many of us have heard about the extreme rainfall of August 1986 that was the result of ex-hurricane Charley and also the lesser known though still reported every now and then, 5th August 1986 deluge. However, you probably have not heard about the washout of 24th/25th August 1905.

On its own merits, August 1905 was a very poor summer month with below average temperature, well above average rainfall and below average sunshine. It followed on from a relatively warm July (CET of 17.2c) with a CET of only 14.7c. Phoenix Park had a mean temperature of only 13.6c compared to a typical August nowadays (1981-2010) which has a mean of 15.2c. The number of days with rain was high with up to 26 such days at Valentia Observatory and even Phoenix Park observed 24 days with rain. Roches Point observed the least with 19 such days.

The month was disturbed with Ireland being threatened by deep depressions on numerous occasions. The first of these depressions pushed up from the southwest on 4th August 1905. Valentia Observatory observed a minimum pressure of 982mb from this depression which is quite significant for the time of year although Belmullet would see a record low MSLP of 968mb in August 1959. This low would weaken and fill day by day along with its associated troughs but continue to meander around Ireland bringing further bouts of showery rain.




A ridge finally pushed up from the southwest by the 12th. This would bring a fine few days with reasonably sunny days though cloudy in the north at first. This would result in the only "warm" weather of the entire month. Birr Castle peaked at 23.5c on the 16th.



Westerlies came back with a bite from the 17th onwards with the high pressure collapsing. There was frequent showers and cool days with maximum temperatures stuck in the mid-teens at best as the westerly airflow brought air masses to Ireland from the North Atlantic.



On the 23rd, low pressure made its way eastwards across the UK and Ireland with high pressure from the Azores ridging to the southwest of Iceland. This forced another low pressure in the Atlantic to undercut to the southwest of Ireland. Through the next few days, this low would slowly progress eastwards across the south of Ireland as it got blocked somewhat by ridging over Europe. There was plentiful precipitation associated with this low.

This would become one of Ireland's worst "rainstorms" in recorded history. It resulted in a destructive flood at Bray according to UK Met Office report which is no surprise with such an exceptional rainstorm. Find a 28th August 1905 Irish Times extract below on Arklow streets being flooded along with a little report on the Shannon overflowing from the rain too:







Some of the highest rainfall totals recorded at Irish stations during the period:

Bray, Fassaroe, Co. Wicklow with 114.3mm on the 25th
Newcastle, Co. Wicklow with 104.4mm on the 25th
Dublin City with 87.4mm on the 25th
Phoenix Park, Co. Dublin with 85.1mm on the 25th
Trinity College, Co. Dublin with 83.8mm on the 25th
Clongowes Wood College, Co. Kildare with 74.4mm on the 25th
Roches Point, Co. Cork with 50.8mm on the 24th
Birr Castle, Co. Offaly with 49.3mm on the 25th

These totals are comparable to the exceptionally wet days of 25 August 1986, 11 June 1993, 9 August 2008, 24 October 2011 and 2 August 2014 in the east.




When the low that brought the intense rainfalls cleared, another one pushed in from the Atlantic on the 27th into the 28th bringing more rain to places that didn't need it.



This low would progress eastwards on the 29th and allow a northerly flow bringing cool air but drier weather too.





Data from the UK Met Office.
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09-08-2019, 14:09   #992
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July 2019 with an Irish rainfall total (based on an 11-station grid) of 67.3mm was nothing exceptional. Julys 2011, 2013, 2014 and 2018 were all drier whilst it was just barely drier than July 2016. Even January 2019 was slightly drier than July. Of course, regional differences do occur.

2019 *generally* has been changeable in terms of Irish rainfall when you compare the country as a whole though the south and east have tended to be relatively drier than average up to July. However, Spring 2019 was quite wet (second wettest of the decade just behind 2015) despite the dry May and this was largely down to an exceptionally wet March (approximately the wettest in Ireland since March 1982). Winter 2018-19 was dry and Summer 2019 so far has been close to average rainfall wise with a relatively wet June and relatively dry July.



Data from Met Éireann.
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12-08-2019, 22:29   #993
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After analysing the data we currently have from Irish climate stations for this year's warm Easter period, I found the highest temp recorded was 23.9c at Listowel, Co. Kerry on 19th April (Good Friday) which would make it the warmest April temp in Ireland since 2003.

Ardfert, Co. Kerry recorded 23.5c on 21st April 2011 (Maundy Thursday) - this temp was joint equaled twice during 2019 spell and Belmullet, Co. Mayo recorded 24.2c on 17th April 2003 (Maundy Thursday also). Amusing how all these temps coincided with Easter.

Some of the highest temps during the period 17th-23rd April 2019.

1. 23.9c at Listowel on the 19th
2. 23.5c at Killarney on the 19th
3. 23.5c at Lullymore on the 20th
4. 23.1c at Athy on the 20th
5. 23.1c at Glasnevin on the 21st
6. 23.0c at Ardfert on the 19th

Daily max records considering the data I have (so not confirmed):

Wed 17th Apr - 16.6c at Ardtarmon
Thu 18th Apr - 22.0c at Dooks
Fri 19th Apr - 23.9c at Listowel
Sat 20th Apr - 23.5c at Lullymore
Sun 21st Apr - 23.1c at Glasnevin
Mon 22nd Apr - 22.3c at Ballyshannon
Tue 23rd Apr - 21.1c at Sligo Airport

This was a rather impressive spell for consecutive days of 20c+ in Ireland as usually such a day in April is a one off.

Casement Aerodrome had 4 consecutive days of 20c or more from 19th to 22nd April 2019. Dunsany had 4 consecutive days of 20c or more also from 19th to 22nd April (including a new April record max of 22.2c on the 20th). Mullingar and Phoenix Park had the same as Casement and Dunsany. Edenderry had 5 consecutive days with 20c or more from 19th to 23rd April as did Lullymore.

Data from Met Éireann.

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14-08-2019, 18:53   #994
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Following on from the coldest Winter since 1962-63 and the coldest Spring since 1962, Summer 1979 wasn't anything to write home about. It was cool, wet and dull but not exceptionally so, therefore a very forgettable Summer in the sense of the overall statistics. However, this season stands out for one single event that occurred in mid-August 1979. This was of course the Fastnet Storm.

From a synoptic stand point, what happened was that a depression of approximately 1010mb at this time near Newfoundland in Canada moved eastwards over the North Atlantic Ocean on the 11th/12th August. Rather than the low filling and weakening, it did the opposite with it intensifying as it got closer to Ireland. The low pushed into the southwest of Ireland on the night of the 13th being directed northeastwards over the country. At midnight on the 14th, minimum pressure dropped to 984mb in contrast to the pressure being 1010mb at 16:00 on the 13th. This was a 26mb drop in pressure in an 8-hour period and it was officially a "weather bomb" or in scientific terms, explosive cyclogenesis. What defines a weather bomb is that the pressure of a low drops at least 21mb within a 24-hour period and in this case, the pressure dropped 26mb from 1010 to 984mb within 8 hours! Many of the storms or weather bombs you know of in recent times like say the 9/10 December 2014 or 23 December 2013 have their pressure dropping gradually over the 24-hour period but in August 1979, the pressure dropped very rapidly which led to high seas and unseasonably windy conditions.

From Met Éireann:



The maximum wave height recorded at The Marathon Gas Platform was 14.5 metres. In comparison, Storm Darwin of 12 February 2014 caused a maximum wave height of 25m at the Kinsale Energy Gas Platform. August 1979's wave height may not seem that extreme here compared to Darwin but you got to remember that a race was taking place and not to mention, this was in the Summer season.

Look how the low evolves.







Satellite for near midday on 14th August 1979.



Hundreds of yachts were lost and unfortunately, there were 15 fatalities courtesy of the storm.

Was it unprecedented? No. Summer storms like it have happened before and have happened since. They are rare due to the weak zonal flow in Summer time. Two other examples of Summer storms include the one in July 1956 and in July 1988.

http://news.bbc.co.uk/onthisday/hi/d...00/3886877.stm

Data come from Met Éireann.
40th anniversary now of the Fastnet disaster.

https://twitter.com/rtenews/status/1...339203586?s=21
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20-08-2019, 10:23   #995
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Highest temps I have found for February 2019 from the synoptic stations and climate stations' data that have come in so far so still no country record (18.1c at Phoenix Park in February 1891) beaten but an exceptional amount of 17.0c observations recorded and on four separate days too.

17.6c at Delphi Lodge on 25th Feb 2019
17.5c at Killarney (Muckross House) on 25th Feb 2019
17.3c at Delphi Lodge on 26th Feb 2019
17.3c at Mount Dillon on 25th Feb 2019
17.2c at Casement Aerodrome on 26th Feb 2019
17.2c at Glasnevin on 15th Feb 2019
17.1c at Dooks on 27th Feb 2019
17.0c at Valentia Observatory on 26th Feb 2019
17.0c at Dooks on 26th Feb 2019

Data from Met Éireann.

Last edited by sryanbruen; 20-08-2019 at 11:15. Reason: EDIT: Thanks Artane2002!
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20-08-2019, 11:14   #996
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Quote:
Originally Posted by sryanbruen View Post
Highest temps I have found for February 2019 from the synoptic stations and climate stations' data that have come in so far so still no country record (18.1c at Phoenix Park in February 1891) beaten but an exceptional amount of 17.0c observations recorded and on three separate days too.

17.6c at Delphi Lodge on 25th Feb 2019
17.5c at Killarney (Muckross House) on 25th Feb 2019
17.3c at Delphi Lodge on 26th Feb 2019
17.3c at Mount Dillon on 25th Feb 2019
17.2c at Casement Aerodrome on 26th Feb 2019
17.2c at Glasnevin on 15th Feb 2019
17.1c at Dooks on 27th Feb 2019
17.0c at Valentia Observatory on 26th Feb 2019
17.0c at Dooks on 26th Feb 2019

Data from Met Éireann.
Looks like four separate days rather than three. The 15th, 25th, 26th and 27th. Incredible for February!
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29-08-2019, 11:29   #997
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Up to 28th, Casement Aerodrome has seen 180.4 hrs of sun this August making it the sunniest August since 2010 there (183.6 hrs) and sixth sunniest on record back to 1964. I think this is more a reflection of how dull August has been as a summer month recently rather than how sunny this August is. Like in comparison, August 1995 had 252.7 hrs and August 1976 had 236.0 hrs - the only two Augusts that have had a monthly sun total of at least 200 hrs at Casement. It will be the sunniest month of the year (unless September turned out to be exceptionally sunny) in Dublin it looks like.

Dublin Airport has seen almost 20 hours less than Casement with 161.1 hrs although still the sunniest August here since 2010.

Data from Met Éireann.
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02-09-2019, 15:09   #998
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With a monthly Irish rainfall total of 149.0mm (based on an 11-station grid), August 2019 was the wettest August of the 2010s decade and the wettest month since January 2018. Previous wettest August was 2012 with 122.0mm.



In terms of rainfall anomalies to average, August 2019 saw the highest deviation from average since December 2015 with 58.7mm above the 90.3mm average.

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03-09-2019, 13:56   #999
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297mm Athenry
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03-09-2019, 14:44   #1000
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Originally Posted by sryanbruen View Post
Up to 28th, Casement Aerodrome has seen 180.4 hrs of sun this August making it the sunniest August since 2010 there (183.6 hrs) and sixth sunniest on record back to 1964. I think this is more a reflection of how dull August has been as a summer month recently rather than how sunny this August is. Like in comparison, August 1995 had 252.7 hrs and August 1976 had 236.0 hrs - the only two Augusts that have had a monthly sun total of at least 200 hrs at Casement. It will be the sunniest month of the year (unless September turned out to be exceptionally sunny) in Dublin it looks like.

Dublin Airport has seen almost 20 hours less than Casement with 161.1 hrs although still the sunniest August here since 2010.

Data from Met Éireann.
In the end, Casement had 190.6 hrs of sun during August 2019 making it the fourth sunniest August on record at the station and sunniest since 2003. It's also the first year to have August as the sunniest month of the year in Dublin since 2003 (assuming September won't be record sunny). Most other stations had May as their sunniest month.
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13-09-2019, 14:58   #1001
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Just looking at some short term stats here, and have noted that regarding the running 90 day (or near 3 months) average for Ireland, that we have not gone into a negative figure yet this year, which if the trend continues, and likely it is, would be first time this has happened since 2014. This rough graph might better explain (black line is 90 day running deviation from 1981-2010 avg, while blue is the 28 day)



As the chart suggests, I would really need to look further back into the data to see if this is a sort of pattern which occurs regularly or more part of a longer term change in trend. Regardless, interesting in itself I think.


All data used is from the mighty Met Eireann.

Last edited by Oneiric 3; 13-09-2019 at 15:02.
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