Convective / Storm Discussion - 22nd October onwards 2013

[Guest William Grimsley]

Next week? maybe:

 

 

 

 

That's interesting. Thunder snow?

[Convective]

Reports of thunder from parts of Donegal apparently. A few of them showers look quite lively out there. Good unstable evening out there.

 

Anyone fancy heading down to the West coast of Italy with me..?

 

[Coast]

Anyone fancy heading down to the West coast of Italy with me..?

 

 

Are you paying?!

 

A big juicy level 1 for severe wind gusts from ESTOFEX for Scotland and the North today:

 

 

 

Storm Forecast

Valid: Tue 19 Nov 2013 06:00 to Wed 20 Nov 2013 06:00 UTC

Issued: Tue 19 Nov 2013 01:25

Forecaster: TUSCHY

A level 1 was issued for Scotland and N-UK mainly for strong to severe wind gusts.

 

SYNOPSIS

 

A strong upper trough over NW Europe continues to amplify south. A decaying upper low over the C-Mediterranean gets caught by this approaching trough and a constant NE-ward motion of this decaying upper low is expected during the forecast. A strong cyclogenesis occurs N of Scotland and a confined but healthy depression exists over the W-Mediterranean. Both features are described more in detail below. Strong high pressure over E-Europe keeps the weather calm.

 

DISCUSSION

 

The main risk with that feature will be a confined area with strong to severe wind gusts, which runs from south of Sardinia to the Tyrrhenian Sea to S-C Italy. Strength of LL winds, LCLs below 800 m and some SBCAPE/LLCAPE also points to a somewhat enhanced tornado risk with onshore moving showers/thunderstorms. The tornado risk seems to be maximized over S-Sardinia (noon and afternoon) and around Napoli (Italy, 00-06Z). An isolated strong event can't be ruled out. For now a level 1 was issued due to ongoing uncertainties regarding strength and final track of that depression.

 

... Scottland and parts of UK, 00-06 Z...

 

Rapid cyclogenesis is forecast SE of Iceland and N of Scotland during the overnight hours. This deepening rate is driven by impressive dynamics (e.g. left exit of a 55 m/s jet stream at 500 hPa). Despite rapid advection of higher theta-e air towards the center, no warm seclusion process is yet anticipated ( which will affect this forecast area during the following day ! ). Therefore, our main concern will be the southbound racing cold front. Warm ELs and meager prefrontal moisture lower confidence in more than isolated storms. However, intense forcing and some low-end SBCAPE should assist in the development of a forced line of shallow convection, which races to the south. Postfrontal pressure tendencies don't look that strong mainly due to the rapidly developing back-bent occlusion to the north. Nevertheless we expect strong to severe wind gusts as postfrontal winds at 850 hPa increase to 25-30 m/s. A level 1 should cover that event due to a rapid weakening trend onshore and deteriorating environmental conditions for a more severe and widespread convectively induced wind event. Also, confidence in more than spotty lightning activity is quite low.

 

 

 

Watch out for that spotty lightning!!!

[Coast]

Lightning Wizard GFS shows those convective gusts:

 

Iceland gets battered:

 

 

 

 

Then Scotland is under some helicity:

 

 

Big convergence:

 

[Stuart]

I look out for the spotty lightning Coast

[Methuselah]

Is it contagious?

[Stuart]

Last Update: 1100UTC Tuesday 19th November 2013  

SKYWARN UK SEVERE WEATHER WATCH #040ISSUED: 1100UTC TUESDAY 19TH NOVEMBER 2013

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE WEATHER AS FOLLOWS:STRONG, POTENTIALLY DAMAGING WINDS - WESTERN, NORTHERN, NORTH-EASTERN AND EASTERN SCOTLAND, ORKNEY AND SHETLAND

IN EFFECT FROM 2300UTC TUESDAY 19TH UNTIL 2300UTC WEDNESDAY 20TH NOVEMBER 2013

LOW PRESSURE PASSING CLOSE TO THE NORTHEAST QUARTER, BRINGING AN ACTIVE COLD FRONT FOLLOWED BY GALES AND SEVERE GALES FROM THE NORTH DOWN ITS WESTERN FLANK.

DISCUSSION:

THERE IS GOOD MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF A SEVERE WEATHER RISK THROUGH WEDNESDAY. A LOW PRESSURE SYSTEM MOVING SOUTH-EAST FROM ICELAND WILL DEEPEN TO NEAR 984MB AS IT APPROACHES THE NORTHEAST OF SCOTLAND. AN ACTIVE COLD FRONT PUSHES SOUTH INTO NORTHERN HALF OF SCOTLAND, WITH SLIGHT INSTABILITY BUT IMPRESSIVE FORCING LEADING TO A POTENTIAL FOR CONVECTIVE GUSTS ABOVE 55MPH TO BE MIXED DOWN TO THE SURFACE AFFECTING WESTERN SCOTLAND AND ISLANDS AND PARTS OF NORTHERN AND EASTERN SCOTLAND, THOUGH DIMINISHING INLAND. BEHIND THIS, STRONG GRADIENT WINDS WILL INCREASE FROM THE NORTH UP TO AROUND 50MPH, GUSTING TO PERHAPS ABOVE 70MPH, DOWN ITS WESTERN FLANK WITH COASTAL AREAS MOST EXPOSED TO THE RISK. HIGHER GROUND AND LOWLAND IN LEE OF HIGHER GROUND WILL ALSO EXPERIENCE STRONG GUSTS, INCLUDING SOUTHERN FACING AREAS. HIGHER GROUND AND AREAS OF INLAND SCOTLAND MAY ALSO SEE BLIZZARD CONDITIONS FOR A TIME, REDUCING VISIBILITY. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

 

SPOTTER ACTIVATION IS REQUESTED AND SPOTTERS ARE REQUESTED TO REPORT ALL FACTORS EXCEEDING ACTIVATION CRITERIA

 

http://www.skywarn.org.uk/current.html

[Nick F]

Storm & Convective Forecast

 

Issued 2013-11-20 08:15:05

Valid: 20/11/2013 0800 to 21/11/2013 0600

 

 

THERE IS A RISK OF THUNDERSTORMS FORECAST

 

Synopsis
Deep long-wave upper trough lies across much of Europe and the eastern side of Britain, while a ridge extends north over the N Atlantic. A surface depression NE of Scotland at 0800z will continue SSE across the North Sea today, associated cold front will surge south across England and Wales, clearing S England early afternoon.

... ENGLAND and WALES ...

Cold front, currently across N England and N Wales, will continue to surge south this morning, clearing the south coast of England early this afternoon. A strong jet aloft and veering wind profiles towards the surface (creating strong deep-layer shear) will mean a squall line is likely to form along the cold front, as forced ascent of the 'warm' sector occurs. Strong convective wind gusts, brief intense rainfall, sporadic lightning and small hail are likely with passage of the squall line. Also, given strong veering of winds at the surface, an isolated tornado can't be ruled out. But main risks will be strong wind gusts and intense rainfall with risk of localised flooding.

Edited November 20, 2013 by Nick F

[Coast]

Storm & Convective Forecast

 

You beat ESTOFEX to it this morning Nick!

 

 

Storm Forecast

Valid: Wed 20 Nov 2013 06:00 to Thu 21 Nov 2013 06:00 UTC

Issued: Wed 20 Nov 2013 08:06

Forecaster: PUCIK

A level 1 was issued for western coastline of Greece, Albania and Western Turkey mainly for excessive precipitation and to the lesser degree for marginally large hail and tornadoes.

 

SYNOPSIS

 

Satellite imagery reveals several disturbances embedded in the large pool of low geopotentials over Western and Central Europe. Two most distinct ones are as of 06 UTC centered over northern Scottland quickly moving to the south and over southern France that will translate towards southeast across the Western Mediterranean. Several other short-wave troughs are observed especially at the southern flank of the pool in the westerly to southwesterly flow over the Mediterranean. A frontal zone will run from the Central Mediterranean towards Hungary and Eastern Poland. In contrast to the previous days, convective activity will be less significant albeit western coastline of southern Balkans and Turkey deserve some closer inspection.

[Coast]

Interesting across the SE from lunchtime:

 

 

 

 

 

 

[Coast]

 

SKYWARN UK SEVERE WEATHER WATCH #040

ISSUED: 1100UTC TUESDAY 19TH NOVEMBER 2013

 

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE WEATHER AS FOLLOWS:

STRONG, POTENTIALLY DAMAGING WINDS - WESTERN, NORTHERN, NORTH-EASTERN AND EASTERN SCOTLAND, ORKNEY AND SHETLAND

 

IN EFFECT FROM 2300UTC TUESDAY 19TH UNTIL 2300UTC WEDNESDAY 20TH NOVEMBER 2013

 

LOW PRESSURE PASSING CLOSE TO THE NORTHEAST QUARTER, BRINGING AN ACTIVE COLD FRONT FOLLOWED BY GALES AND SEVERE GALES FROM THE NORTH DOWN ITS WESTERN FLANK.

 

DISCUSSION:

 

THERE IS GOOD MODEL AND PARTNER AGENCY CONFIDENCE IN THE POSSIBILITY OF A SEVERE WEATHER RISK THROUGH WEDNESDAY. A LOW PRESSURE SYSTEM MOVING SOUTH-EAST FROM ICELAND WILL DEEPEN TO NEAR 984MB AS IT APPROACHES THE NORTHEAST OF SCOTLAND. AN ACTIVE COLD FRONT PUSHES SOUTH INTO NORTHERN HALF OF SCOTLAND, WITH SLIGHT INSTABILITY BUT IMPRESSIVE FORCING LEADING TO A POTENTIAL FOR CONVECTIVE GUSTS ABOVE 55MPH TO BE MIXED DOWN TO THE SURFACE AFFECTING WESTERN SCOTLAND AND ISLANDS AND PARTS OF NORTHERN AND EASTERN SCOTLAND, THOUGH DIMINISHING INLAND. BEHIND THIS, STRONG GRADIENT WINDS WILL INCREASE FROM THE NORTH UP TO AROUND 50MPH, GUSTING TO PERHAPS ABOVE 70MPH, DOWN ITS WESTERN FLANK WITH COASTAL AREAS MOST EXPOSED TO THE RISK. HIGHER GROUND AND LOWLAND IN LEE OF HIGHER GROUND WILL ALSO EXPERIENCE STRONG GUSTS, INCLUDING SOUTHERN FACING AREAS. HIGHER GROUND AND AREAS OF INLAND SCOTLAND MAY ALSO SEE BLIZZARD CONDITIONS FOR A TIME, REDUCING VISIBILITY. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

 

 

[TheToastPeople]

Morning all, was pretty surprised to be woken up earlier by a rumble of thunder and hail hitting my window! Not to shabby for November

[Coast]

Thunder, sleet, snow the lot being reported now in the SE/EA regional thread as the front comes down across the country!

[Coast]

[emilyc]

Had 3 claps of thunder here (Woking, Surrey) about 30 mins ago and some hail, although it's cleared now.

[Stormyking]

Wow its violent out there! very very strong winds, torrential rain and have has 4 cracks of thunder!

[Neilsouth]

Almost looks like sleet, but we've also had hail... bloody cold now too

[Coast]

A quiet period coming up to see November out:

 

 

 

[East_England_Stormchaser91]

Meanwhile, it looks like Zeus is hitting Rhodes, Kos and Turkey big time!! Sat24 showing an area of lightning that looks comparable to the size of England!

[matty40s]

Cairngorm forecast for Friday is the cold coming back in with a bang and thunderstorms.

[Coast]

Cairngorm forecast for Friday is the cold coming back in with a bang and thunderstorms.

 

 

Nothing showing on GFS really yet, maybe some snow on higher ground:

 

[Convective]

Thunderstorms north of Glasgow and Edinburgh! Two well established lines of cells moving north-eastwards and putting out a few sferics!

[lorenzo]

No escaping the weather.. just when you think you have had enough for one day and try to get some zzzzzs

[poseidon]

Estofex shows a slim chance of some electrical activity over southern UK....

 

 

"Another feature of interest is a mid level frontal boundary in the surface level warm sector with elevated instability of up to 200 J/kg MUCAPE between the Azores and southern England. GFS computes significant convective precipitation signals. EL is colder than -20°C and there is a sort of atmospheric river of moist air (8-10 g/kg) rapidly advected to the English south coast with rain sums locally exceeding 15 mm."

Edited December 15, 2013 by poseidon

[Convective]

More thunderstorms just teasing the northwest coast of Scotland.

Meanwhile here there has just been a fairly strong squall as this rain made landfall! Wind has decreased rapidly again now.