Convective / Storm Discussion - 31st July onwards 2013

[Bluebreezer54]

Seen some very tornadic looking skies North and East of Peterborough, saw some real low level cloud moving at a rapid pace, pity I didn't have my camera on me.

Shame on you. What sort of storm chaser leaves home without a camera ?!

[East_England_Stormchaser91]

Shame on you. What sort of storm chaser leaves home without a camera ?!

I was on my way to the girlfriends house driving through what was light drizzle, then all of a sudden, I must've drove into that line of showers that I saw when I checked the radar! Gutted! Camera was at home !

[WillinGlossop]

Temp 19c dew 18c quite warm/ sticky out there.....

[Convective]

Nice Estofex forecast.

[Summer Sun]

Chief Forecaster's assessment for tomorrows yellow rain warning for London and the south east

 

After another spell of hot weather there is the potential for thundery rain to affect parts of SE England. However the most likely outcome is considered to be a "near miss", where the worst of the thundery activity runs just to the south and east of UK land areas.

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&regionName=se&fcTime=1375398000

[NO LONGER POSTING]

Chief Forecaster's assessment for tomorrows yellow rain warning for London and the south east

 

After another spell of hot weather there is the potential for thundery rain to affect parts of SE England. However the most likely outcome is considered to be a "near miss", where the worst of the thundery activity runs just to the south and east of UK land areas.

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&regionName=se&fcTime=1375398000

 

We want this.. 

 

Guys it wont happen..

 

Then it might.. just might happen

 

[Biggin]

Chief Forecaster's assessment for tomorrows yellow rain warning for London and the south east

 

 However the most likely outcome is considered to be a "near miss", where the worst of the thundery activity runs just to the south and east of UK land areas.

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&regionName=se&fcTime=1375398000

 

 

 

Quelle Surprise 

Edited August 1, 2013 by Biggin

[Supacell]

Whats with the thick cloud cover here?

[robt]

Whats with the thick cloud cover here?

It feels like I'm sat in a sauna.

[Darren Bown]

There's a lovely breeze here today, but as soon as it drops, ther air becomes thick. The office is stifling today!

[wimblettben]

I have just noticed there are a few slightly unstable looking mid level clouds to my south.

 

Don't know whether this maybe a good sign or not for something thundery somewhere later today.

[Stuart]

SKYWARN UK SEVERE THUNDERSTORM WATCH #028
ISSUED: 1000UTC THURSDAY 1ST AUGUST 2013

SKYWARN UK FORECASTS THE POTENTIAL FOR SEVERE WEATHER AS FOLLOWS:
HEAVY RAIN LEADING TO A RISK OF LOCALISED FLOODING - NORTHERN IRELAND, NORTHERN & WESTERN SCOTLAND
STRONG, POTENTIALLY DAMAGING WIND GUSTS - NORTHERN IRELAND, WESTERN SCOTLAND & NORTHEAST ENGLAND
LARGE, POTENTIALLY DAMAGING HAIL - NORTHERN IRELAND, WESTERN SCOTLAND & NORTHEAST ENGLAND
BRIEF POTENTIALLY DAMAGING TORNADOES - NORTHERN IRELAND & NORTHEAST ENGLAND

IN EFFECT FROM 1000UTC UNTIL 2300UTC THURSDAY 1ST AUGUST 2013

MOIST AND UNSTABLE AIRMASS WITH STRONG CAPPING FOSTERING HIGH INSTABILITY

DISCUSSION:
THERE IS GOOD MODEL AND PARTNER AGENCY AGREEMENT ON THE POSSIBILITY OF SEVERE THUNDERSTORM RISKS THROUGH THE PERIOD, IN TWO MAIN AREAS. ACROSS IRELAND, THE FRONTAL ZONE IS EXPECTED TO PROVIDE A FOCUS FOR CONVECTIVE DEVELOPMENT THROUGH TODAY, WITH STRONGER INSTABILITY EXPECTED LATER WITH AFTERNOON HEATING. THOUGH THE MAIN AREA OF CONVERGENCE IS WELL WEST OF NORTHERN IRELAND, MATURE CELLS MAY MIGRATE NORTHWARD FROM EIRE DURING THE AFTERNOON AND EVENING. GIVEN HIGH PWAT VALUES AND LESS CAPPING, THESE STORMS ARE EXPECTED TO GENERATE HEAVY RAINFALL WITH SOME LOCATIONS SEEING SUCCESSIVE OR BACKBUILDING CELLS WHICH MAY LEAD TO EXCESS SURFACE WATER AND FLASH FLOODING, ESPECIALLY GIVEN RECENT RAINFALL IN THE AREA. STRONG INSTABILITY MAY ALSO GENERATE INCIDENTS OF MODERATE TO LARGE HAIL SIZES IN STRONGER CELLS. LATER IN THE AFTERNOON, CONVECTION FROM IRELAND IS EXPECTED TO ADVECT OVER WESTERN AND NORTHERN SCOTLAND WITH SIMILAR RISKS POSSIBLE THERE. THE OVERALL DIRECTIONAL SHEAR PROFILE, AND LOW LEVEL SHEAR GIVEN A STRONG LOW LEVEL JET UP THE FRONTAL ZONE SUGGEST ORGANISED STORMS WITH ATTENDANT STRONG GUSTS AND POSSIBLE TORNADOES.

WHILE THE MAINLAND WILL REMAIN HEAVILY CAPPED THROUGH THE DAY, VERY HIGH INSTABILITY IS EXPECTED TO BE GENERATED BY INCUBATION OF SURFACE TEMPERATURES UP INTO THE HIGH 20'S WITH HEALTHY DEWPOINTS. CONVERGENCE OWING TO HIGH GROUND AND COASTAL EFFECTS ACROSS NORTHEAST ENGLAND, AND PERHAPS EASTERN SCOTLAND, MAY SERVE AS A FOCUS FOR STRONG CONVECTION. WHILST INITIATION HERE IS LESS CERTAIN, ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL FOR LARGE HAIL AND STRONG GUSTS OWING TO ROBUST UPDRAFTS AND AMPLE DEEP LAYER SHEAR. SUPERCELL MODES ARE POSSIBLE, ALLOWING FOR A POSSIBLE TORNADO RISK, THOUGH THESE ARE NOT EXPECTED TO BE STRONG GIVEN MEAGRE LOW LEVEL FLOW. THIS WATCH MAY BE 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

Edited August 1, 2013 by Stuart

[weatherobsuk]

Cant tell from vis satellite image, but looks like a MCS to the south of Ireland (offshore) where the low-pressure LLC should be? could be interesting for southern Ireland if so.

[A.J]

I have just noticed there are a few slightly unstable looking mid level clouds to my south.

 

Don't know whether this maybe a good sign or not for something thundery somewhere later today.

yep, same thing here Ben...bands of Ac trying to develop Cas turrets but then starting to flatten, indicative of  a a little lower/mid instability with a capped upper mid-level

[BrickFielder]

 Estofex----------------At mid-levels, steep lapse rates have started to spread northward and will overlap with the moisture. Current thinking is that elevated storms will develop over a broad region. During the day, storms will have a greater potential to root to the boundary-layer. Storms that form may be capable of producing large hail and tornadoes given the moderate low-level vertical wind shear. Main potential will be the British Isles, but a weak threat cannot be excluded for northern Germany and Denmark. Limiting factor will be the increasing capping inversion that will suppress deep moist convection further to the south.----------------Yet most of the models do not agree. Certainly there appears to be some instability forecast for today.For surface bound storms though you need some sort of trigger and there really is not much of a trigger. Perhaps late afternoon early evening in some parts of Northern England.As for the elevated storms that Estofex is thinking about then humidty through the mid levels is rather low.Despite that forecast SkewT's do suggest posibilities for elevated and surface based storms today.Overnight soundings do hint at a CAP though which is not clear on the forecast skewT's.Overall the greatest risk today is in Ireland, but there is just a hint of risk (20%) for parts of Northern England. Wind speed shear and drier air aloft could indicate a slight tornadic risk as well. Its one of those situations where some models are not so keen and 8 times out of 10 they will be right. Still worth a quick discussion though.

 

 

[Darren Bown]

Those convergence zones place me in a prime spot for any storm formation this evening, if anything. Will be keeping an eye out.

[wimblettben]

Have just noticed that the Met Office have taken away their warnings in the southeast for thundery rain.

 

Not suprising really, its a shame because theres obviously pleanty of instability about availiable but the Caps just too strong.

Edited August 1, 2013 by wimblettben

[Guest William Grimsley]

Any showers/thunderstorm for East Devon for tomorrow?

[BornFromTheVoid]

Galway Bay this afternoon

 

[shaky]

There nothing forecasted today thunderwise for england and wales but i swear i can see convective clouds going up in the distance here in leicester!!looking more towards kettering and northampton!!just taken a look at sat 24 and there seems to be a bank of cloud coming in from the channel across the centre of england!!any thought anyone??

[TheToastPeople]

There nothing forecasted today thunderwise for england and wales but i swear i can see convective clouds going up in the distance here in leicester!!looking more towards kettering and northampton!!just taken a look at sat 24 and there seems to be a bank of cloud coming in from the channel across the centre of england!!any thought anyone??

The sky has gone rather convective looking round these parts, But im not expecting any storms seems as the capping is pretty strong. Just a case of clouds bubbling up in the heat of the day, they wont be around for long i suspect.

[Utahraptor]

Lightning strikes now detected towards the north west of Ireland

[NL]

There nothing forecasted today thunderwise for england and wales but i swear i can see convective clouds going up in the distance here in leicester!!looking more towards kettering and northampton!!just taken a look at sat 24 and there seems to be a bank of cloud coming in from the channel across the centre of england!!any thought anyone??

Thunderstorms are forecast to effect quite a large portion of England and Wales (50+%) and a level1 issued for most of Ireland and northern parts, only the far SW and South Central and South East have a lower chance put around 15%

.

http://www.estofex.org/

[Supacell]

Looking at the charts there are several possibilities for severe thunderstorms to occur over the next 2 days but whether they will form is the question

 

Ireland today looks to have the opportunity to develop some severe thunderstorms, with this area being the highest risk with less capping and more influence from the low pressure area to our west. Southern and Western Ireland look particularly good with the risk of 2-3cm hail, gusty winds and torrential rain bringing the risk of flooding, especially where cells line up and backbuild. There is also a risk of tornadoes here with some strong helicity and shear. Basically, all the parameters slotted into place for a severe threat.

 

This evening the NE of England along the eastern Pennines eastwards, north of the Humber is another area to watch. If the cap is broken, and that is a big if, then explosive convection would occur with storms taking advantage of high CAPE values, 40knts of DLS and some helicity which would lead to the risk of severe thunderstorms, maybe even supercells with large hail and torrential rain the greatest threat along with frequent CG lightning. These storms would rumble on into the first part of the night - if they do indeed initiate.

 

Tomorrow there now looks to be a brief risk of severe thunderstorms over Lincolnshire looking at the 6z GFS. CAPE build up of over 1000j/kg, this time less capped, coupled with some 60knts of Deep layer shear would allow thunderstorms to organise bringing a risk of torrential downpours, gusty winds and large hail. I would not be surprised to see a level 1 from Estofex for this risk tomorrow if it still there on the 12z. It is a brief window though, with most storm activity offshore by the time we get to evening.

 

A lot to watch

[Convective]

Tomorrow there now looks to be a brief risk of severe thunderstorms over Lincolnshire

 

Oh, surprise, surprise...