Convective/Thunderstorm Discussion : Spring/Summer 2017

Meteorite58

George Sunsnow

https://twitter.com/estofex/status/899746707231080448

Meteorite58

http://www.convectiveweather.co.uk/forecast.php?date=2017-08-22



Day 2 Convective Outlook
VALID 06:00 UTC Tue 22 Aug 2017 - 05:59 UTC Wed 23 Aug 2017

ISSUED 21:57 UTC Mon 21 Aug 2017

ISSUED BY: Dan

Plume of high WBPT will be drawn northwards across the British Isles on Tuesday, ahead of an approaching Atlantic upper trough. Shortwaves running ahead of the main trough will provide the focus for mostly mid-level instability release, resulting in elevated showers and perhaps a few thunderstorms - the greatest risk of deeper, more widespread convection seems most likely on Tuesday evening / night as better forcing arrives from the southwest, destabilising the plume.


Some uncertainty exists as to the extent of this destabilisation (especially considering the messy mix of stratiform vs convective precipitation), and hence how widespread lightning activity may be - a SLGT has been issued for now, though this could perhaps be upgraded locally to a MDT should confidence improve. In general, better forcing and shear will be found towards the NW, whilst instability will be more significant farther southeast. Should any convection become rooted in the boundary layer, more likely late afternoon/early evening, then there would be scope for an isolated tornado - particularly across northern parts of the Republic of Ireland into Northern Ireland. Some hail is also possible, but the greatest threat will probably be from localised surface water issues given embedded convective elements.

prinzeugen

You have 4 hours to see this.. Never get thunder in my part of Dublin..

Live

https://www.youtube.com/watch?v=ifmuEH-Lg1c

pad199207

Orange warning from Met Eireann

"Widespread thunderstorm activity likely this afternoon and evening"

A bit vague but exciting nonetheless

Mac_

[font=Open-Sans, sans-serif]Storm & Convective Forecast[/font]
[font=Open-Sans, sans-serif][/font]
[font=Open-Sans, sans-serif]Issued 2017-08-22 06:31:30
Valid: Tuesday 22 August 6am to Wednesday 23 August 6am[/font]
[font=Open-Sans, sans-serif]Day 1 Convective / Storm Forecast[/font]
[font=Open-Sans, sans-serif]Synopsis
Upper and collocated surface low (the weakened remnants of ex-Hurricane Gert) will pull a plume of warm and humid air of sub-tropical origin across the UK, which will destabilise across Ireland/N. Ireland initially then across Scotland and N England Tuesday evening/night.
… IRELAND, N. IRELAND, SCOTLAND, N ENGLAND and N WALES …
 A plume of warm and humid air advecting north across the British Isles on Tuesday, with wet-bulb potential (WBPT/Theta-w) values reaching 16-18C and characterised by steep lapse rates, will contribute to modest CAPE values reaching 300-700 j/kg ahead of cold front moving in across the far west during the evening and reaching N. Ireland, Wales and SW England early hours of Wednesday.
This potentially unstable airmass will be capped across much of the UK during Tuesday, however, falling heights and cooling aloft with approach of upper low from the Atlantic combined with divergence in left exit of jet stream, shortwave trough and drier air aloft moving NE across the west will create large scale ascent which will destabilise the plume across Ireland/N Ireland initially in the afternoon … supporting development of heavy showers and thunderstorms, which will then develop or spread northeast across N England then the southern half of Scotland Tuesday evening and overnight into Wednesday morning as forcing moves NE.
30-40 knots of deep layer shear, strong upper level winds/divergence and linear forcing along/ahead of surface cold front will support organisation of convection/storms into clusters/line segments capable of producing torrential rainfall leading to flash-flooding, strong straight-line winds and hail. Increasing low level shear ahead of cold front and low LCLs (Lifted Condensation Levels or cloud bases) indicated across the west may support an isolated brief tornado too across Ireland, N. Ireland and NW England during diurnal heating cycle before risk drops after dark as surface/boundary layer becomes stable and storms become elevated.
Have issued a MARGINAL risk, mainly for flooding, across Ireland, N Ireland, far N of Wales, N England and SW Scotland.
... SW / CENTRAL S ENGLAND ...
There is a risk of some elevated heavy showers and thunderstorms across the above areas, mainly this morning before perhaps waning, though risk of isolated thunderstorms along S coastal areas through the day and into the evening as warm moist advection destabilises in mid-levels.[/font]
[font=Open-Sans, sans-serif]Issued by: Nick Finnis[/font]

Mac_

Met Office Yellow Warning
Between 13:00 Tue 22nd and 22:00 Tue 22nd

Outbreaks of rain will become heavy across some parts of Northern Ireland this afternoon and evening. Northern and eastern areas will be most affected. Some short-lived heavy thundery downpours may cause isolated flooding and affect prone sections of road and disrupt travel. The rain will ease early tonight with county Antrim last to see the rain clear.

JCX BXC

No airports on the island of Ireland have it in their forecasts yet.

pad199207

Very messy picture out there.

ronnie3585

JCX BXC wrote: »

No airports on the island of Ireland have it in their forecasts yet.

SIGMETs issued for the Shannon FIR. Big ball of activity in the middle of the country now, nothing electrical yet though.

Oscar Bravo

1104 update from met eireann saying the heaviest of the showers will be over Connaught Leinster and Ulster

Donegal Storm

Flash flooding could be an issue if some of the hi-res models are to be believed, showing upwards of 50mm of rain in a few hours over parts of Ulster.

Convection is exploding on the radar, from patchy drizzle to widespread heavy rain in the space of two hours. Will be an interesting one to follow, potentially right in the firing line here

pad199207

I'm nearly writing this off already. Too messy. Not organisation at all.

Just moderate to heavy rain.

Donegal Storm

pad199207 wrote: »

I'm nearly writing this off already. Too messy. Not organisation at all.

Just moderate to heavy rain.

While you're probably right, it's only just kicked off and warm moist air is already in situ so lack of surface heating shouldn't be a factor.

Have some faith :pac:

pad199207

Lightning now from those cells east of limerick city

Rikand

ronnie3585 wrote: »

SIGMETs issued for the Shannon FIR. Big ball of activity in the middle of the country now, nothing electrical yet though.

Big ball of ****e it is.

Soaked to my skin!

pad199207

That stream of cloud and muck in off the south coast needs to go do one

ninebeanrows

Whilst I expect there to be a few thunderstorms across the country today - I can't see it meriting an orange alert. Hopefully I am wrong!!

pad199207

Weathercheck wrote: »

Whilst I expect there to be a few thunderstorms across the country today - I can't see it meriting an orange alert. Hopefully I am wrong!!

I think the orange alert is for the risk of flooding more so Thunderstorms.

Plenty of the wet stuff around today without thunder

ronnie3585

Looks like we're threading the eye of the needle here in Galway. For once.

Comhrá

I'm going for another mid-August bust.

pad199207

Definelty a bust now, unless something gets going in the south later

JCX BXC

pad199207 wrote: »

I think the orange alert is for the risk of flooding more so Thunderstorms.

Plenty of the wet stuff around today without thunder

Nothing about flooding in the warning. Only thunder.

Storm 10

Well I am no expert but looking at the current radar I cannot see where this Thunder that ME forecast is going to come from. There is no sign of the rain they said we would get either, bone dry in Galway

cml387

There seems to be some instability building up in East limerick/Tipp at the moment.
Maybe too soon to call it off yet.

thomasj

Netweather had the forecast at thunderstorm possibility for Dublin tonight earlier. They have updated in the last hour or two to say just cloudy with no possibility of rain

George Sunsnow

There's certainly some instability up there still
Took this a few minutes ago near Arklow

Al_Coholic

Huge rattle of thunder in east Cavan/north Meath area ....very heavy rain for at least the last hour too

And a big flash of lightning just now

Jpmarn

cml387 wrote: »

There seems to be some instability building up in East limerick/Tipp at the moment.
Maybe too soon to call it off yet.

I find it very dull near Limerick City but no rain here yet

PukkaStukka

Humidity in Dublin city is very noticeable. Does have a stormy feel about it but doubt it will happen...:(