Summer 2019 - General Discussion

DOCARCH wrote: »

June 2012....my wettest month on record! What a month. 242.4mm.

Interesting. What was your highest daily rainfall of it?

Rainfall totals for a range of selected Irish stations during 1st-8th June 2012 and 10th-14th June 2013.

Good few stations recorded at least 70mm during the period in 2012 (with up to 137.2mm at Carrick-on-Suir, Co. Tipperary) whilst only Valentia Observatory stands out for the period in 2013.



Data from Met Éireann.

Thelonious Monk wrote: »

I may not be able to cycle to work all week due to rain, can’t remember this happening before. Did we have weather this bad in winter or is summer more likely to be the rainier season? Shocking stuff though

Well we did have one of the most anticyclonic winters of the past decade.. other one was 2016-17.

Thing with summer is that it can be exceptionally wet or exceptionally dry depending on the pattern that develops because the jet stream is weakest in late spring and most of summer (due to little contrast in temperatures between the tropics and arctic unlike during winter) so there is not much to give patterns a push. Some years, blocking sets in the right place to deliver us hot weather like 2018 whilst other times, the blocking is in the wrong place to deliver hot weather like it was in every summer from 2007 to 2012, 2015, second half of 2017 and now early summer 2019.

As a case in point, here's a comparison between two different types of blocked summer patterns you can have.

The first chart is from 7th July 2012. There is a trough of low pressure centred over southwestern England with blocking anticyclones out in the Atlantic to the northwest of Ireland and ridging up to Greenland. With a weak jet stream given the time of year, there is nothing to push the low pressure away from the UK and Ireland due to all the high pressure out to the west. Therefore, the low pressure gets stuck around the country for a good few days before eventually getting a push by the 12th July only allowing more areas of low pressure to come in.



This second chart is from 28th June 2018 (the hottest day of the season). There is an omega block of high pressure dominating the UK and Ireland with the jet stream stuck way to the north. Iceland had one of its worst Junes on record with less than 80 hrs of sunshine recorded at Reykjavik if I remember correctly. Our weather systems that would normally affect us were displaced northwards in 2018 by a favourable blocking pattern (Scandi High and a ridgey Azores High) resulting in the coolest summer for Greenland in quite a while as the vast majority of summers have been unusually mild since 2007 there.