The July 1985 Thunderstorm
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18-06-2023 9:47am#1
For those that remember this memorable storm on 25th / 26th July 1985, here is a sequence of images capturing the activity that occurred that day. Feel free to drop in any other images or data you have found about that day (sferics would be a good one). I hope you enjoy taking a look back at this event which is often referred to as the "worst in living memory". This post can also serve as a record of this event to compare with recent and future events.
Met Eireann report of the event :-
Overview of the synoptic pattern the morning of the event. Slack low SW of Ireland and southerly flow :-
Close up of Ireland the morning of the event :-
Lunchtime and the first activity kicks off in the Midlands west of Dublin. Convection occuring over NI :-
Cold cloud tops over the Midlands west of Dublin at lunchtime :-
By 2pm activity is ongoing across the North Midlands with a large amount of convection occurring now in the SE :-
At 5pm activity is widespread away from the immediate SE, SW, and W stretching all the way from Cork up to western counties of Northern Ireland (I personally did not see significant lightning activity in Co.Antrim until 8pm in the evening. Though it was likely ongoing in Tyrone, Fermanagh, Derry at the time).
By 7:30pm there are now two distinct areas of cold cloud tops. One in NI moving towards the north coast, and a larger one moving up the heart of the country. Basically two MCS systems. Note that Northern Scotland was having similar activity at the time with even colder cloud tops :-
By 9pm the northern MCS is moving off shore from the north coast of NI and continuing to develop. The southern MCS is increasing in size and coverage with new development on it's southern flank and stretching out into the Irish Sea west of Isle of Man.
Into the overnight hours, this 11:30pm shot shows a large MCS stretching from Cork all the way up the Midlands, Dublin, Sligo, Dundalk, NI. Also some action in the SE which had be missing out earlier in the day, although images suggest the focus was Midlands, Dublin, and North. Meanwhile the W and SW missed this event altogether.
It's the middle of the night now at 1:00am. And at this stage there is a lot of activity going on where I lived in NI at the time. A large MCS is running up the spine of the country with everywhere except the W, SW, and far SE affected. At this stage if you refer back to earlier images, the Midlands and Northern Ireland would have already had hours and hours of continuous thunder activity :-
2:00am shot appears to show cells decaying the further south you go south :-
At 2:00am the most thunder activity likely occurring over NI. Coldest cloud tops there. Activity likely dying off in the South :-
4:00am shot shows the remainders of the MCS moving north over NI. I can confirm that there was still plenty of lightning action in the North at this time. Further south the event was likely over at this stage with just heavy rain :-
The last of the thunder activity finished up over eastern NI around 9:30am on the 26th. Although looking at 30 min sat images it is now clear that this actually came in from the Irish Sea rather than being a continuation of the overnight MCS :-
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Here are the temperatures for Belfast International Airport from the 25th. Nothing special that day. Also, the METAR reports (current conditions) 25th / 26th for the time period of interest :-
METAR reports from the 25th (see bottom of page) :-
METAR reports from the 26th (see bottom of page) :-
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