Very Warm, Thunderstorms, Flash flooding - Friday through weekend

Kermit.de.frog · 15-07-2014 5:10am #1

On Thursday an area of instability will approach the country from the south after some very warm and humid air embeds itself over the country. Incidentally this brings nice beach and garden weather at times with temperatures in to the mid twenties but also the real threat of some potentially severe storms.

The main focus of concern is Thursday night and Friday morning. This is the period that we could see some severe weather originating in the Bay of Biscay and driving north toward Ireland with focus of attention the south coast but even more so the southeast and east though in reality all areas are at risk.

This will probably materialise and at this point flash flooding is likely so it's something to be aware of. Frequent lightning and some hail is also possible but the hail is more likely during the weekend in western and midland areas. Rainfall totals could mount quickly in downpours.

Having seen the main action through on Thursday night and Friday the focus turns inland for the weekend were thunderstorms should develop when convection gets going during daylight. Though different in origin and homegrown so to speak these could conceivably be unusually large and intense storms for Ireland. All the ingredients are there for intense weather. The midlands, west and north are most at risk over the weekend.

It will be very warm and humid throughout the weekend.

Thunderstorms by their nature are hit and miss. Just make sure you don't caught out! I'm sure the mods will change it as best fits the risk because the models can change suddenly. I'm happy enough with this forecast.

whitebriar · 15-07-2014 8:54am

In theory,if I liked lightning and for that initial biscay push wexfords the place to be.
The fly in the ointment from the thunderstorm point of view is a gale off the Irish Sea.
That could scupper and often does scupper the thunder.
A lot of rain though.

Harps · 15-07-2014 11:12am

BBC forecast this morning warned of 'potent and disruptive thunderstorms' for Friday and Saturday with some very bright colours across Ireland and the UK on the rainfall chart. Temperatures will get above 30C over here with high humidity so it's definitely going to be an interesting spell of weather if all goes to plan

Needless to say though the forecast will change over the next 48 hours so it's still too early to get our hopes up

KingdomRushed · 15-07-2014 1:01pm

England looks set for the really severe weather, more particularly the south and east of England. There will probably be a few thunderstorms here, but I don't think it will be explosive enough for anything truly memorable.

Gonzo · 15-07-2014 2:12pm

temperatures here also will be alot lower than England, particularly eastern Ireland may only see 17-20C over next few days, with higher temperatures of 18-23C in the midlands and west. That's still warm enough for most people.

Iancar29 · 15-07-2014 2:57pm

Not be best to keep everything in the Convective thread no?

Kermit.de.frog · 15-07-2014 3:15pm

At the moment this looks like a potential "event" (that could change) rather than the usual inland convective storms with warnings possible nearer the time from the met agencies so I think it deserves a separate build up and discussion thread. And lets be honest - it's been a pretty straight forward summer so far - so lets hope this sparks some interest.

I see mentioned above the possibility of some high rainfall totals, rates too but I disagree a little about the winds off the Irish sea. I don't think it will be that brisk and in any case on Thursday night it's not the usual inland convective based storms but something more organised from the south that we have to watch. These sort of setups tend to deliver. I have memories of good storms from identical synoptic situations in previous summers.

Will post a more comprehensive update after the 12pm model runs.

Larbre34 · 15-07-2014 3:50pm

Iancar29 wrote: »

Not be best to keep everything in the Convective thread no?

More for modelling, this is no harm for a "golfball hail in my back garden" or "why is it only drizzling" thread, specific to this progged event

goat2 · 15-07-2014 5:36pm

mt cranium made a long term forecast and so far his predictions are right,

Kermit.de.frog · 15-07-2014 6:02pm

whitebriar wrote: »

In theory,if I liked lightning and for that initial biscay push wexfords the place to be.

Some of the higher resolution models certainly giving signals that way and some decent rain rates too.

12 pm GFS delays by 6 hours the advance of the shower troughs on Thursday night and continues it's random precipitation generator. A bit of intuition is needed. We know broadly what the situation will be with pulses of rain and embedded thunderstorms moving north but we'll have to wait another 24 hrs to get a more accurate picture. Be interesting to see the ECM charts later on.

whitebriar · 15-07-2014 7:32pm

Kermit.de.frog wrote: »

Some of the higher resolution models certainly giving signals that way and some decent rain rates too.

12 pm GFS delays by 6 hours the advance of the shower troughs on Thursday night and continues it's random precipitation generator. A bit of intuition is needed. We know broadly what the situation will be with pulses of rain and embedded thunderstorms moving north but we'll have to wait another 24 hrs to get a more accurate picture. Be interesting to see the ECM charts later on.

yup
Isn't it funny how nature repeats itself.
Some of the most fantastic biscay events in my lifetime followed that same pattern with massive storms with mad lightning importing themselves into Wexford.They usually eventually impact the Arklow area but whilst still potent and bloody good near Dublin they lose some ooumph heading north.
Hence they are worth a chase the hour or so down the M11 if they are Biscay/welsh stuff and position yourself on higher ground near the sea (plenty east of Enniscorthy or just north of courtown harbour)
The night Michael Jackson died (google the date,lightning strike records,charts etc) was a classic example of wexfords fortune though I think it was a welsh import that night.
We were teased listening to the long rumbles and all the forks for a good hour non stop in Arklow that night from the storm which at that point was south of Gorey.
2hrs into that and it came overhead.Thunder shaking the house like mortar bombs and continuous non stop forks.
There are in my opinion no storms quite as potent and long lasting as a biscay or welsh import source.

Regarding what I said earlier on the Irish Sea,I just don't want to see a returning lower RH feed entering the mix.

On a related note,serious drought in the Wexford/South Wicklow area (we got none of the recent rain ye got in Dublin) so we could do with these downpours!!

Oneiric 3 · 15-07-2014 11:13pm

whitebriar wrote: »

yup

The night Michael Jackson died (google the date,lightning strike records,charts etc) was a classic example of wexfords fortune though I think it was a welsh import that night.
We were teased listening to the long rumbles and all the forks for a good hour non stop in Arklow that night from the storm which at that point was south of Gorey.
2hrs into that and it came overhead.Thunder shaking the house like mortar bombs and continuous non stop forks.
There are in my opinion no storms quite as potent and long lasting as a biscay or welsh import source.

I was in full storm mode that night so got a chance to cache a couple of radar images as the storm/s moved in. I do recall a lot of sferics being picked up that night along southeast coastal regions.

C/O Met.ie

Chart for 00z that night, thundery trough lines slicing up towards SE coast:

C/O UK Met

We got the remains of those showers (minus the thunder) the next morning; they were monsoonal. Both sky and atmosphere a thick, soupy dark grey as the rain poured, yet everyone was out in their teeshirts. Classic Summer weather. If it rained like that 365/24/7, I'd not mind in the least.

whitebriar · 15-07-2014 11:50pm

Cheers big ears.I'd forgotten the full specifics and how big that storm system/shower was-basically covering all of co wexford as it hit shore.
I think it may have been born around the bristol channel south wales area?

fleet_admiral · 16-07-2014 12:10am

Im going to take a spin down to the Hook on thursday night to (hopefully) see the storm

Elmer Blooker · 16-07-2014 1:16am

The talk here of Wexford thunderstorms reminds me of a big one on this night which was the beginning of the big August heat wave in 2003. I was on me holliers down there and it was absolutely glorious, who needs the Mediterranean when we can get weather like that!

piuswal · 16-07-2014 9:14am

Have a look at www.yr.no for places like Rosslare Harbour (you can in fact enter most places and they'll produce values) for forecasted hourly rainfall values for later Thursday into Friday.

Kermit.de.frog · 16-07-2014 10:44am

Tomorrow night is coming in to the 48 hr range. Euro4 has the focus of the action in the southwest but this will certainly change over the next few outputs.

GFS shows less intense but more widespread pulses of rain with the southeast the main focus.

Very warm tomorrow btw - temperatures in to the mid 20's inland.

The south and midlands of the UK could be in for a hammering during Friday night. They will be getting nice imports from France.

pad199207 · 16-07-2014 11:08am

I predict Heavy Rain pushing up from the South with a few scattered sferics along the Waterford Coastline.

Kermit.de.frog · 16-07-2014 11:15am

pad199207 wrote: »

I predict Heavy Rain pushing up from the South with a few scattered sferics along the Waterford Coastline.

Let's not get ahead of ourselves with the old optimism.;)

whitebriar · 16-07-2014 12:34pm

pad199207 wrote: »

I predict Heavy Rain pushing up from the South with a few scattered sferics along the Waterford Coastline.

Yeah that is a probability given the perfect storm making conditions are way east of us to the south so you might be looking for imports that just dont make it.

Larbre34 · 16-07-2014 2:52pm

Meanwhile, in the alternative reality that is the Irish Indo -

"While the projected rainfall – about 10mm – is usually not enough to fall within warning criteria, the short bursts of rain are a cause of concern for forecasters.

These heavy downpours may be as intense as those seen in Dublin in October 2011 when a number of rivers burst their banks, resulting in widespread infrastructural damage in the city."

Take your pick from lazy, careless, scaremongering.

Billcarson · 16-07-2014 3:51pm

Hope i get some thunderstorms over the coming days,but overall im not really looking forward to the coming weather,warm,humid,sticky,sweaty stuff. Cant stand humidity especially at night when you are trying to get to sleep.

vickers209 · 16-07-2014 4:41pm

Feeling very warm in wicklow at the minute, 25c according to the car while driving

whitebriar · 16-07-2014 4:49pm

Got a peak of 24.4c today and currently 22.1c here in costa del Arklow.
Utterly Balmy.
Lots of penting up energy and we haven't even got high 850s yet.

Thargor · 16-07-2014 4:56pm

Do you think this Sunday will be a hot one in Galway? I mean heatwave temps not just pleasant...

Kermit.de.frog · 16-07-2014 5:34pm

GFS a bit of an upgrade for tomorrow night. We are on track and things are bubbling nicely.

Thargor - perhaps not heatwave temps on Sunday but still very warm, low- mid 20's. However next week could be a hot one but we will have to wait a little longer to see how that develops.

Calibos · 16-07-2014 5:35pm

Hopefully MT's forecast for Sunday is accurate. ie. Reasonably Sunny, Reasonably calm, Reasonably Warm. Bray Airshow is on that day as well as Man U playing Bray Wanderers.

RobertKK · 16-07-2014 6:32pm

The UK met office do seem confident we will get thunderstorms here tomorrow evening/night.

lolie · 16-07-2014 6:33pm

Bbc weather giving heavy possibly thundery showers moving up late tomorrow night.
Any on Saturday in England it's forecasting intense possibly violent thunderstorms and disruption on Saturday.

Larbre34 · 16-07-2014 6:38pm

The Open golf in Merseyside could be rightly messed up.

M.T. Cranium · 16-07-2014 7:49pm

Watching this closely, still think that the zone most at risk of heavy or severe storms would be something like Wexford-Carlow northwest through Laois, Offaly, west Kildare into east Galway, possibly in tandem with a second impulse moving north through Cork, Clare and western Galway, and later these might then reduce below heavy or severe limits moving further north, but Donegal Bay region still in the mix by Friday afternoon. That scenario would be from Thursday late evening to Friday mid-day or afternoon. Having said that, I think it will have the potential to create one or two areas of torrential rainfall resulting in localized flood concerns, so would advise keeping close to the forum (and of course your news media) and/or the radar if you're experienced and know how to use it. Expect cells of concern to your local area to come at you from the SSE.

Saturday's activity is somewhat more of an afterthought but could be significant in parts of north Leinster and east Ulster. That activity would be drifting more from west to east again. Britain appears likely to get a pounding from a frontal zone that develops there Friday night into Saturday, extending from about Newcastle south to London. To the west of this, some long-duration thunderstorm cells could give local rainfalls of 100-150 mm in parts of the east Midlands and regions near London. Back further west for the Open it's more likely to be 25-30 mm. Delays are only likely from lightning dangers as the sandy soil should be able to cope with that fairly easily.

Sunday (back to Ireland) at the present time looks a bit more widely scattered so that most but not all places should have a reasonably fair weather day. This could change closer to the time, however.

I won't be all over this thread given that I am almost on holiday except for an hour or two a day of weather watching, so any further thoughts from me would be over in the forecast thread from time to time.

Very Warm, Thunderstorms, Flash flooding - Friday through weekend

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