Storm Desmond - Heavy Rainfall 4/5 December 2015

omicron wrote: »

All we need now is the ten hour version of this. Could be worse...

Hairy baby are thinking of printing these:

Oneiric 3 wrote: »

Two day totals as per Met.ie

For a comparison from the UK met office. Incredible amount of rain!
Carlisle and Lancaster seem badly hit.

two wheels good wrote: »

For a comparison from the UK met office. Incredible amount of rain!
Carlisle and Lancaster seem badly hit.

Impressive totals. I think though that either those stations are on high ground or near enough to high ground to feel the full impacts of a phenomena known as 'orographic rainfall'. What would make our highest total (105mm) more impressive though is that it occurred at a station located well inland and situated on a lowland plain with no high ground of note in the area.

SeaBreezes wrote: »

More Bandon photos.

https://www.facebook.com/gavin.monaghan2/media_set?set=a.10153850148694668.1073741831.730624667&type=3

dosn't work if your not on Facebook

Oneiric 3 wrote: »

Met ag rainfall total & percentage maps for the last 7 days and for the 7 day period Nov 16th - Nov 22nd 2009, which was the wettest period of that particular month, for comparison.

7 day rainfall totals for each of the periods

In terms of both rainfall totals & percentages for both notably wet 7 days periods, the last 7 days were actually slightly wetter than the wettest period in 2009, at least in parts of the west. And on closer inspection, not just parts of the west, but pretty much most of the country too.

Maps from Met.ie

Where on the site are those details?

Stats from storm Desmond from met.ie

[IMG][/img]

mayo.mick wrote: »

Stats from storm Desmond from met.ie

[IMG][/img]

440 year return period. Impressive.

maquiladora wrote: »

440 year return period. Impressive.

Its great to have another record here in Mayo :pac:

Zzippy wrote: »

Most hopelessly optimistic football fans in one county?

Why, are they all Liverpool fans or something?

Thanks for all those recent posts, will have to have a close look at the site of Derrypark (Mayo) to see if it might approximate highest potential rainfall in the orographic zone. My post mortem on this prolific rain event was that models gave us a reasonable preview although some of them made it appear a little more localized to high ground than it turned out to be in Connacht at least, perhaps in Kerry and Donegal this was more the case although Malin Head and north Donegal in general seemed to get very heavy falls without much orographic influence.

As the very heavy rain spread out over a large portion of Connacht it gave more scope for regional flooding to develop than if the extreme rainfalls had been on higher ground and let's say 40-60 mm had fallen lower down. So point taken on that issue for any future situations.

If anyone happens to know with more precision where the Derrypark rain gauge is located, that might speed up my search. I'm mainly interested in assessing whether there would be potentially heavier rainfall locations in the general area. From what was recorded in Cumbria in the same event, one suspects a local max of 250-300 mm to be quite possible. As to the return periods shown on the met.ie graphic, something around 400 years is of course very approximate, it could in reality be anywhere from 100 to 1,000, if I had to guess, 200 mm of rain in a little over 48h might not have a 400 year return period, I suppose the main clue might be historical records of flooding as prior to about 1850 there would not be much actual rainfall measurement data for comparison.

Also, once again as stated elsewhere, thanks to moderators and various forum members for taking timely action on thread "development" and everything worked out well, I certainly support the concept of split threads if warning levels are not the same, avoids confusion, also in this case it made it a lot easier for general boards users to find the type of information of most concern to them. The split happened just about when I was thinking that the original title needed more of a level three emphasis and I was trying to figure out how not to have that sound like a level three wind warning, so good moves all around by the weather forum unpaid (ahem) staff.

I see where that heavy rainfall (Derrypark) location is, at least approximately, near Mayo-Galway border at southwest end of Lough Mask. Fast rising ground to the north with 600m elevation gain nearby, so this probably is about the event epicentre as far as we can tell.