Uk General Convective Discussion & Forecasts, 10th October 2012>

[Coast]

Sorry a bit late really, but there isn't much on the horizon for England for a few days:

[Supacell]

Despite it being mid-November and the chances of thunderstorms is continually dwindling, I am still keeping one eye on those slight possibilities.

And so onto tonight, there could be some sferic activity along Channel coasts and maybe getting inland south of the M4, as per Estofex latest forecast:

http://www.estofex.org/

There looks to be some overnight CAPE across CS England, maybe Isle of Wight a good place to be.

Will most likely stay out to sea, if it occurs at all, but worth a heads up I feel

[Coast]

And so onto tonight, there could be some sferic activity along Channel coasts and maybe getting inland south of the M4, as per Estofex latest forecast:

http://www.estofex.org/

There looks to be some overnight CAPE across CS England, maybe Isle of Wight a good place to be.

Blimey I'd neglected to look at convective chances this late in the year, cheers Supacell for the reminder!

Here's that ESTOFEX chart:

and a few more sources to see if we think the chances are good or not:

21st OWS seem to think not:

Aviation briefing has it further North and with wider coverage:

GFS lightning Wizard has very little to support things other than a bit of SB CAPE this afternoon:

and some low Lapse rates along the South coast:

The best I can see is demonstrated by this simple format GFS overview:

You might need good eyesight and hearing for anything today!

Edited November 16, 2012 by Coast

[Andy Bown]

I think it will take a particularly heavy burst of rain from an embedded CB to bring anything thundery very far inland from the South coast. Guess it depends how

slow the Cold Front is moving NW-SE allowing pulses of activity to run SW-NE along it.

(We nearly had a week with no posts in this thread)

Edited November 16, 2012 by Andy Bown

[DAVID SNOW]

Just had a loud crack of thunder, very suprised.

[Supacell]

Just had a loud crack of thunder, very suprised.

A little east of where I was thinking it would be, but good stuff. I wonder if there will be more tonight for you southern folk?

[Coast]

Focus on Scotland and the North West today?

Storm Forecast

Valid: Mon 19 Nov 2012 06:00 to Tue 20 Nov 2012 06:00 UTC

Issued: Sun 18 Nov 2012 21:56

Forecaster: TUSCHY

SYNOPSIS

A broad upper trough over the C-Mediterranean shifts to the east and becomes more or less stationary atop the Ionian Sea. Unsettled conditions continue over most parts of the Mediterranean.

The frontal zone is far displaced to the north with numerous strong low pressure areas affecting Ireland and Scotland during the forecast period. Any thunderstorm activity west of Ireland/Scotland remains very sporadic.

SKYWARN UK SEVERE WEATHER WATCH #063

ISSUED: 2100UTC SATURDAY 17TH NOVERMBER 2012 (GJ/GS)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:

NORTHERN IRELAND

SCOTLAND

NORTHERN ENGLAND

ISLE OF MAN

WALES

SOUTHWEST ENGLAND

IN EFFECT FROM 0000UTC MONDAY 19TH UNTIL 0000UTC TUESDAY 20TH NOVEMBER 2012

DEEPENING LOW CROSSING THE NORTHWEST SECTOR BRINGING GALES AND INTENSE RAIN WITH STRONG GUSTS

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...FLASH FLOODING...GALES...STRONG GUSTS

DISCUSSION:

THERE IS STRONG MODEL AGREEMENT ON THE POSSIBILITY OF A SEVERE WEATHER RISK THROUGH MONDAY, AS A SURFACE LOW DEEPENS TO 980MB AND MATURES AHEAD OF A LARGE UPPER TROUGH OVER THE ATLANTIC. AN ACTIVE SET OF FRONTS WILL BRING HEAVY RAIN AND GALES, REACHING OVER 50MPH THROUGH THE IRISH SEA AND ADJACENT AREAS. STRONG GUSTS, POSSIBLY EXCEEDING 70MPH, MAY OCCUR WITH HEAVY RAIN ACROSS THE AREAS SPECIFIED IN THE WATCH, WITH FURTHER STRONG GUSTS POSSIBLE THROUGH NORTHERN IRELAND AND NORTHWESTERN SCOTLAND LATER MONDAY. ALSO, LEE WAVING DOWNWIND OF HIGH GROUND MAY SEE STRONG GUSTS OCCURRING IN AREAS OF EASTERN SCOTLAND AND NORTHERN ENGLAND. OVERALL RAINFALL ACCUMULATIONS OF 30MM ARE EXPECTED, WITH PERHAPS 60MM POSSIBLE OVER HIGH GROUND AND WESTERN COASTAL AREAS AS WELL AS WHERE LEE WAVE EFFECTS OCCUR AS STATED. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

Risk of flooding?

Lapse rates down the West coast:

But more extensive areas of shear and tornado possibilities:

and some big gusts around midday:

Hang on to your hats up there!

[Coast]

Still some emphasis on the low pressure system off Scotland today:

Short wave trough / cold front crosses western Europe and only some sporadic lightning activity might be possible within the cold maritime airmass over western UK

All out to the West:

Look at the Lapse rates out there ( http://en.wikipedia.org/wiki/Lapse_rate) :

A wide coverage of gusty winds again today:

A slight chance of thunderstorms embedded in the activity off to the West of Scotland and Ireland today?

[Coast]

There's a few threads that could benefit from today's charts, but these are the convective elements of what could be on its way today:

Storm Forecast

Valid: Thu 22 Nov 2012 06:00 to Fri 23 Nov 2012 06:00 UTC

Issued: Wed 21 Nov 2012 21:26

Forecaster: GATZEN

SYNOPSIS/DISCUSSION

A ridge extends from the central Mediterranean to eastern Europe. An intense trough will move into north-western Europe during the period. This will be associated with a cold front moving into the North-Sea region and northern France. Stable air masses will limit convection over most places. In the wake of the cold front, some showers and thunderstorms may develop near the trough's base due to rather steep lapse rates and relatively moist low-level air.

SKYWARN UK SEVERE WEATHER WATCH #064

ISSUED: 2230UTC WEDNESDAY 21ST NOVEMBER 2012 (GJ/SG/RB/SM)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:

ENGLAND WALES NORTHERN IRELAND WESTERN SCOTLAND CHANNEL ISLANDS

IN EFFECT FROM 0000UTC THURSDAY 22ND UNTIL 0600UTC FRIDAY 23RD NOVEMBER 2012

MATURE LOW PRESSURE SYSTEM COMBINED WITH UPPER JET BRINGING STRONG WINDS/HEAVY RAIN.

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...FLASH FLOODING...GALES...STRONG GUSTS...BRIEF FUNNELS/TORNADOES

DISCUSSION:

A STRONG AND MATURE LOW CENTRED BY ICELAND, COUPLED WITH A CYCLONIC UPPER JET FORCES A WELL DEFINED COLD FRONT ACROSS THE UNITED KINGDOM. WIND CONVERGENCE AHEAD OF THE FRONT WILL LIKELY CREATE SQUALL LINE CONDITIONS OVER THE SOUTHERN HALF OF THE UNITED KINGDOM. PRE-FRONTAL WINDS OF UP TO 45MPH OVER HIGH GROUND IN PARTS OF THE SOUTH WEST ACCOMPANIED BY INTENSE RAINFALL RESULTS IN 20MM ACCUMULATIONS IN 3 HOURS WITH TOTALS OF OVER 40MM LIKELY FOR THE SOUTH-WEST, NORTHERN AND CENTRAL ENGLAND WHILE 50MM CAN BE EXPECTED OVER WALES AND THE WEST MIDLANDS. STRONG HORIZONTAL WIND SHEAR ALONG THE COLD FRONT MAY PRODUCE BRIEF FUNNELS/TORNADOES OR OTHERWISE ENCOURAGE STRONG GUSTS IN EXCESS OF 70MPH. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

More rain in areas already flooded and susceptible to flooding:

Mega shear ahead of the front:

Gusty winds up to 70 mph on the coasts:

Maybe some thunder and lightning in the West of Scotland and Ireland later?

Edited November 22, 2012 by Coast

[Coast]

TORRO have a warning out too:

A TORRO CONVECTIVE DISCUSSION has been issued at 23:40GMT on Wednesday November 21st 2012

Valid from/until: 00:00 - 02:00GMT on Thursday 22nd/Friday 23rd November 2012 for the following regions of the United Kingdom & Eire:

Eire N Ireland England, Wales, Scotland, IoM, Channel Is

THREATS

Tornadoes; wind gusts to 70mph; torrential rain; isolated CG lightning

SYNOPSIS

A large upper trough to the west of the British Isle will move slowly eastwards whilst a well-marked cold front also moves eastwards. A powerful warm conveyor belt ahead of the front will tend to back as the upper trough sharpens, increasing low-level lift up and over the frontal surface. Forced line 'convection' is expected along the surface front, although the evolution of this is expected to be complex, and it may break up into several lines. Strong flow ahead of and along these lines may allow for misocyclones to run up the frontal zone - where any low-level convergence/lift is maximised, tornadoes are possible. The highest threat appears to be across parts of Eire, Wales, and SW England.

Very gusty winds are also likely along and ahead of the frontal zone.

Given the uncertainties over the evolution and also instability ahead of the front, a discussion has been issued rather than a watch. However, this forecast is unlikely to be updated on Thursday, due to work commitments - however, it is possible that a somewhat higher tornado threat could develop, should the line convection become well-organised.

http://www.torro.org.uk/site/forecast.php

[Coast]

Are we up for a bit of convective action today then?

Storm Forecast

Valid: Sun 25 Nov 2012 06:00 to Mon 26 Nov 2012 06:00 UTC

Issued: Sun 25 Nov 2012 07:33

Forecaster: VAN DER VELDE

SYNOPSIS

An intense depression lies over the North Sea and moves slowly to northern Denmark. The pressure gradients surrounding it are very tight and produces gale conditions from eastern England to western Denmark with the strongest winds north of the Netherlands. This depression currently is wrapping up its occlusion, surrounded by a WV dry slot. Its cold front is not well defined at low levels. The mid level cold front pushes into France and Germany. No deep convection is forecast around this low.

West of Ireland lies a satellite low with comma cloud appearance which is becoming the main low as the day progresses. Cold airmass at mid altitudes advects southward over the Celtic Sea. Cold convective cloud tops (EL<-20°C) allow some thunder, but CAPE is marginal along the occlusion, better in the cold airmass. By the end of the period instability is enhanced over the English Channel and storms may affect the UK south coast. An isolated severe gust or tornado is not ruled out, but the CAPE-shear overlap is not well established (in GFS model) and lacks veering with height. In some WRF models, SREH is locally around 200 m²/s² in the unstable air in the Channel.

But later tonight:

Maybe it's more like tomorrow morning?

Edited November 25, 2012 by Coast

[Nick F]

Risk of some heavy showers and a few storms for Sern England today:

Valid: 26/11/2012 07:00 - 27/11/2012 06:00

Headline: ... THERE IS A RISK OF THUNDERSTORMS FORECAST ...

Synopsis

Slow-moving deep upper trough will continue to dig S/SE across western Europe, while associated surface low tracks slowly east across S England.

... S ENGLAND ...

Polar airmass across Sern Britain, characterised by steeper lapse rates, will follow cold front clearing eastern England this morning. Lapse rates will be steepest across Sern England beneath 500mb cold pool (circa -30C), this will create around 100-200 j/kg CAPE - especially towards southern coastal counties with relatively warmer maritime flow at the surface coming onshore beneath cold pool.

Scattered heavy showers and a few thunderstorms seem likely through the day, with a risk of hail and heavy downpours leading to a risk of localised flooding in places. Although wind shear will be rather weak, some organisation/training of cells is possible near one or more minor troughs moving through. Risk should susbside later this evening, as wind switches offshore bringing drier surface air from the north.

Issued by: Nick F - Forecaster for Netweather

Also can be found here: http://www.netweather.tv/index.cgi?action=convective;sess=348f5ba217cb0fa78b98f3640998470a

[Coast]

Nothing from ESTOFEX so far today, SkyWarn say:

SKYWARN UK SEVERE WEATHER WATCH #066

ISSUED: 1630UTC SUNDAY 25TH NOVEMBER 2012 (GJ/GS/RB)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:

NORTH WALES NORTHERN ENGLAND MIDLANDS SOUTHWEST ENGLAND SOUTHERN ENGLAND

IN EFFECT FROM 1800UTC SUNDAY 25TH UNTIL 1200UTC TUESDAY 27TH NOVEMBER 2012

COLD CORE ATLANTIC LOW SLOWLY TRANSITING SOUTHERN UK

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...PERSISTENT RAIN...RIVER FLOODING...LIGHTNING...FUNNELS/WEAK TORNADOES

DISCUSSION:

THERE IS MODERATE MODEL AND PARTNER AGENCY CONFIDENCE OF THE POSSIBILITY FOR FURTHER WEATHER RISKS OVER THE PERIOD. A SLOW-MOVING LOW SYSTEM CROSSES THE SOUTHERN HALF OF THE UK IN THE BASE OF THE UPPER TROUGH. DESPITE LOW MOISTURE VALES THE ATMOSPHERE IS DEEPLY SATURATED AND SOME PERIODS OF HEAVY RAIN MAY AFFECT NORTH WALES AND NORTHERN ENGLAND, THOUGH PERSISTENT RAIN WILL BRING A MORE WIDESPREAD RISK GIVEN RECENT OVER-SATURATION OF GROUND AROUND SOUTHWEST ENGLAND AND THE MIDLANDS. WEAK INSTABILITY AND STRONG DYNAMICS CLOSE TO THE LOW CENTRE MAY GENERATE THE POSSIBILITY OF STRONGER CONVECTION INTO THE SOUTH COAST AND SOUTH CENTRAL ENGLAND THROUGH MONDAY, PERHAPS WITH THE RISK OF WEAK TORNADOES GIVEN LOW LEVEL HELICITY. THIS WATCH MAY BE UPDATED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

Plenty of SBCAPE in the South and West:

Lapse rates up:

Tornado risk looks to be more towards France?

But here's the thunderstorm symbols for later on!

[virtualsphere]

Last Thursday (22nd November) my son was born at 11:45am in Carmarthen and later in the afternoon there was a thunderstorm ahead of the cold front which produced a couple of loud bangs which were audible from the hospital room. Unfortunately, although I could make out the flashes, I couldn't see much due to the frosted glass in the room and with my mind on other (my wife would say, more important) things I wasn't really in a position to be checking out the radar or sferics!

Yesterday we had a phone call from a family friend who my wife had left a message with a few days ago about the birth. She apologised for not replying sooner - it turns out she had only just received our message because the lightning strike I'd seen from the hospital had struck her house and incinerated her telephone line. According to her report, a ball of lightning entered her neighbour's adjoining house through a window which was slightly open, which caused all of the electrical equipment in the property to buzz. The telephone line and power cables were pretty much destroyed and most of the electrical equipment was ruined including her husband's computer which was on the Internet at the time and "turned to ash" (not sure how much exaggeration there is here). The fire brigade were called and said that the occupants were lucky to be alive.

Anyway, this is probably a long shot but I'm wondering if anyone happens to have any radar grabs / sferics plots for that day? The time would have been sometime between 1 and 3.30pm, hospital postcode SA31 2AF. It would be interesting to see what happened and save them for posterity so I can show my son one day!

[Methuselah]

Congrats Dad!

[Coast]

A rumble up the Cheshire gap today according to the BBC?

None of the usual sites are showing any forecasts, so what do the charts say?

21st OWS, say no:

Aviation weather has a maybe:

Some low levels of MLCAPE around the UK coastline:

A bit of ICAPE and shear:

+ rain (maybe hail?)

Lapse rates up:

Simple format GFS :

Showing something off the North coast of Scotland and Ireland midday:

Otherwise I'm not sure what the BBC are alluding to at the moment?

Edited December 4, 2012 by Coast

[jamesbhx]

There was a thunderstorm in the Shoreham/Brighton vicinity between 1830 and 1900 this evening. A few flashes of forked lightening and loud thunder with some torrential rain and gusty winds. Anyone else witness it? It was one of the best I've seen this year funnily enough!

[Coast]

There was a thunderstorm in the Shoreham/Brighton vicinity between 1830 and 1900 this evening. A few flashes of forked lightening and loud thunder with some torrential rain and gusty winds. Anyone else witness it? It was one of the best I've seen this year funnily enough!

Damn I missed that!! I could have swung past that way on the journey home too

[Coast]

Keeping an eye on the end of this week.....

[Robbie Garrett]

Slight bit of mid-level convection at the moment falling as rain. I do wonder, any chance of this convection improving coast as the temperatures drop??

[Coast]

Sunday still then?

[Coast]

Tomorrow stacking up to be interesting:

Rain, lots of it:

Substantial shear out over France and clipping the Channel coast:

Gusty, convective wind:

Leading into a few days of convective possibilities:

[Nick F]

Convective potential developing from the west Friday afternoon onwards over the weekend across southern and western areas . Polar maritime flow following the cold front bringing the heavy rain north and east tomorrow will be characterised by steep lapse rates, particularly over coastal areas where cold air aloft contrasts with the relatively warmer SSTs. So heavy showers and thunderstorms look to drift onshore across southern and western areas - most frequent near southern and western coasts, but the 500mb southwesterly flow should drive convection inland too. Should be some hail mixed in.

Makes a change from the rather quiet spell convective-wise since late November.

Edited December 13, 2012 by Nick F

[virtualsphere]

Yes, looks like a potentially active few days coming up for us western coastal folks with some heavy showers and hail and thunder a possibility starting tomorrow evening and through into the weekend. NMM brings the negative LI figures quite far inland along the south coast as well come Saturday. Something to keep an eye on!

[Coast]

Morning storm fans!

Unsurprisingly, ESTOFEX have a forecast for today:

Storm Forecast

Valid: Fri 14 Dec 2012 06:00 to Sat 15 Dec 2012 06:00 UTC

Issued: Thu 13 Dec 2012 20:33

Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

A diffluent cyclogenesis affects far NW Europe with mid-level cold air spreading rapidly east towards France and UK. Induced more zonal flow pattern results in rising height fields over SW Europe and keeps this area stable convective-wise. However, intense rain affects Portugal/NW Spain with abundant subtropical moisture spreading ashore. Weak lapse rates keep the main bulk of precipitation non-convective and therefore no level area will be added.

Cold and stable conditions continue over E-Europe.

The main show for some deep convection arises over the NE Atlantic within the highlighted areas. We issued a low probability lightning area due to missing LL convergence foci despite some marginal better chances along the westward facing coasts. Onshore moving thunderstorms may pose a local strong wind and marginal hail risk, but those storms become rapidly detached from the moist maritime BL which results in a fast onshore weakening trend.

SkyWarn on the case too:

SKYWARN UK SEVERE WEATHER WATCH #067

ISSUED: 1530UTC THURSDAY 13TH DECEMBER 2012 (SG/GJ/GS)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:

SOUTHWEST ENGLAND SOUTH WALES NORTHERN IRELAND WESTERN SCOTLAND

NORTHEAST SCOTLAND ORKNEY & SHETLAND ENGLAND

IN EFFECT FROM 0000UTC FRIDAY 14TH DECEMBER UNTIL 2359UTC SATURDAY 15TH DECEMBER 2012

ACTIVE FRONTS SPREADING NORTHEAST WITH A DEVELOPING LOW CIRCULATION PROVIDING INTENSE RAIN AND SEVERE GALES

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...LOCALISED FLOODING...GALES...STRONG GUSTS...DAMAGING GUSTS...HEAVY SNOW...BLIZZARDS

DISCUSSION:

THERE IS GOOD MODEL CONFIDENCE OF A SEVERE WEATHER RISK THROUGH FRIDAY AND SATURDAY. A BROAD LOW COMPLEX TO THE WEST SETS UP FRONTS INTO FRIDAY WHICH COME UNDER THE INFLUENCE OF A STRONG JETSTREAM, DEVELOPING A NEW LOW PRESSURE AND CIRCULATION TRANSITING FROM THE CELTIC SEA ACROSS SCOTLAND THROUGH THE WATCH PERIOD. EARLY FRIDAY, A STRONGLY DYNAMIC FRONTAL ZONE BRINGS RAINFALL ACCUMULATIONS POSSIBLY EXCEEDING 30MM IN A FEW HOURS INTO SOUTHWEST ENGLAND, SOUTH WALES AND WESTERN SCOTLAND OWING TO ENHANCEMENT FROM STRONG WINDS. ELSEWHERE, LESS THAN 20MM IS EXPECTED THOUGH MOST WESTERN AND SOUTHERN COASTAL AREAS MAY SEE HIGHER. ALONG THE LEADING EDGE OF THIS FRONT PRECIP MAY AT FIRST BE SNOW, PROVIDING BLIZZARD CONDITIONS FOR NORTHERN IRELAND, WESTERN SCOTLAND AND NORTHERN ENGLAND BEFORE TURNING TO RAIN. HIGHER GROUND MAY SEE ACCUMULATIONS EXCEEDING 10CM WITH DRIFTING SNOW. AS THE FRONT SPREADS WEST THROUGH FRIDAY, WINDS OF 30-40MPH GUSTING TO ABOVE 60MPH ARE EXPECTED IN EXPOSED SOUTHERN COASTAL AREAS AND OVER HIGH GROUND. DURING SATURDAY, THE NEW DEEP LOW TIGHTENS THE PRESSURE GRADIENT OVER THE NORTH SEA, WHICH MAY RESULT IN SEVERE GALES WITH DAMAGING GUSTS FOR FAR NORTHEASTERN PARTS OF SCOTLAND AND THE ORKNEY AND SHETLAND ISLES, AND STRONG GUSTS FOR MOST OF THE EASTERN SIDE OF THE MAINLAND. THIS WATCH MAY BE UPDATED OR UPGRADED. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY.

Nothing yet from UKASF or TORRO, 21st OWS showing the TStorm potential:

Aviation weather:

Here comes the system with associated MLCAPE:

Shear and convergence:

France has mega shear, we also get some of it (look out for helical activity!):

Gusty winds:

and plenty of rain:

Higher lase rates don't start affecting us until later:

But there is some moisture in that system:

What does it all give us then?

Plenty of rain and gusting winds, maybe up to 60 mph on exposed coasts and in The Channel, with a chance of a tornado or spout. Possible small rumble form TStorms out to sea later in the day?

Edited December 14, 2012 by Coast