Uk Convective General Discussion & Forecasts, 12th to 14th August 2012

[Eskimo]

The south could get some sferics soon.

[A.J]

must admit I'd be somewhat sceptical reading reports of seeing lightning from 100 miles distance, so I've just popped outside, and sure enough saw 3 flashes to NNW in about 5 minutes, and I'm just 10 miles north of Wolverhampton!!...Flashes must be at least 80 miles away...astonishing!

[Slowpoke]

Very unexpected storm that was, it's moving away now! Was quite the corker!

Mighty Blackpool!!!

Edited August 13, 2012 by Slowpoke

[I Cumbria Marra I]

its cloudy here so cant even see

[Chris D]

Very unexpected storm that was, it's moving away now! Was quite the corker!

Mighty Blackpool!!!

Pretty much every storm we get is unforecasted or unexpected lol. And they always seem to be at night for some reason!

[liambailey09]

Doesn't surprise me some of you are seeing flashes from such long distances. Earlier on in the year I could see lightning at least 75 miles away to my east towards the essex coast, gradually getting brighter until over me.

Looking forward to see how wednesday pans out, have the day off work and also looks like saturday night might be good if something can bust the cap!

[Tim B]

must admit I'd be somewhat sceptical reading reports of seeing lightning from 100 miles distance, so I've just popped outside, and sure enough saw 3 flashes to NNW in about 5 minutes, and I'm just 10 miles north of Wolverhampton!!...Flashes must be at least 80 miles away...astonishing!

Indeed, lightning seems to be shooting out of the tops of these clouds as its moving closer to me now and the flashes aren't as distinct. Lower level clouds must be scattering the light more.

[IanR]

just back from watching a nice lightning show from the back window, some vivid sheet lightning at times but still to far to hear the thunder , started well over an hour ago and still seeing faint occasional flashes

[Supacell]

I could see flashes from the viewpoints near my house too, just got back in after watching it.

[Costa Del Fal]

must admit I'd be somewhat sceptical reading reports of seeing lightning from 100 miles distance, so I've just popped outside, and sure enough saw 3 flashes to NNW in about 5 minutes, and I'm just 10 miles north of Wolverhampton!!...Flashes must be at least 80 miles away...astonishing!

Last year in a storm during September (10th??? Sometime in September anyway!) I remember seeing Lightning flashes coming as far as Oxfordshire and Gloucestershire from my house! :D

[NUT]

Started raining here but light (for now) tomorrow may well be a different matter or anytime in next few hours possibly depends on how bands move or weaken or whatever

[I Cumbria Marra I]

thats the 2nd time tonight that a storm has hit cumbria and turned into a light/moderate rain shower, f*** it am going to bed!

[Convective]

Just been treated to 2 hours of continuous lightning miles out over the sea!

[Chris.R]

Well that was a lovely storm. As other people have mentioned, could see the lightning for ages after the storm had passed. Some really great strikes towards Southport! The closest strike was only about 2 miles away, and I think the core of the storm passed somewhere towards Formby way. Was quite fun actually, because I was standing on Crosby Beach, sheltering under the Crosby leisure centre porch. The rain was bouncing off the roof, the thunder was reverberating around and the lightning was just spectacular. The rain was torrential, and a lot of the roads around here are completely flooded! My first storm of the year, and hopefully not my last. Very surprised and amazed to hear that the lightning could be seen that far away. The Northwest storm shield, especially in Merseyside seems to be broken at last, so it just shows, when the right ingredients are there, amazing things can happen around here. PS: sorry I couldn't report during the storm, but as you can imagine I was too busy watching the lightning, and I didn't want my phone to get wet!

[Convective]

Well that was a lovely storm. As other people have mentioned, could see the lightning for ages after the storm had passed. Some really great strikes towards Southport! The closest strike was only about 2 miles away, and I think the core of the storm passed somewhere towards Formby way. Was quite fun actually, because I was standing on Crosby Beach, sheltering under the Crosby leisure centre porch. The rain was bouncing off the roof, the thunder was reverberating around and the lightning was just spectacular. The rain was torrential, and a lot of the roads around here are completely flooded! My first storm of the year, and hopefully not my last. Very surprised and amazed to hear that the lightning could be seen that far away. The Northwest storm shield, especially in Merseyside seems to be broken at last, so it just shows, when the right ingredients are there, amazing things can happen around here. PS: sorry I couldn't report during the storm, but as you can imagine I was too busy watching the lightning, and I didn't want my phone to get wet!

Saw all of it from here!

[Cheshire Freeze]

Well that was a lovely storm. As other people have mentioned, could see the lightning for ages after the storm had passed. Some really great strikes towards Southport! The closest strike was only about 2 miles away, and I think the core of the storm passed somewhere towards Formby way. Was quite fun actually, because I was standing on Crosby Beach, sheltering under the Crosby leisure centre porch. The rain was bouncing off the roof, the thunder was reverberating around and the lightning was just spectacular. The rain was torrential, and a lot of the roads around here are completely flooded! My first storm of the year, and hopefully not my last. Very surprised and amazed to hear that the lightning could be seen that far away. The Northwest storm shield, especially in Merseyside seems to be broken at last, so it just shows, when the right ingredients are there, amazing things can happen around here. PS: sorry I couldn't report during the storm, but as you can imagine I was too busy watching the lightning, and I didn't want my phone to get wet!

Saw a flash in the NW horizon as I left work but thought it couldn't possibly be a storm as there had been no evidence of even rain round here today. Still firmly in the NSC here unfortunately.

In terms of Wednesday, the NAE doesn't make too much of the rain.

Edited August 13, 2012 by CreweCold

[Hathers]

Check out estofexs warning for the incoming front on Wednesday

http://www.estofex.org

[Costa Del Fal]

How much cloud is likely on Wednesday?? This is likely to be the only real inhibiting factor imo but in these situations there quite often regularly seems to be a cloud issue.

[Cheshire Freeze]

How much cloud is likely on Wednesday?? This is likely to be the only real inhibiting factor imo but in these situations there quite often regularly seems to be a cloud issue.

I can't see the 'event' being more than a period of moderate- heavy rain TBH. The SB CAPE figures will only really be realised under periods of insolation and, as the highest figures appear to coincide with the front passage, I can't really see much of a convective threat IMO.

[Robbie Garrett]

Damn, if that continued to go north... Southern England wouldn't exist come the next morning if anything did kick off.

[Coast]

Damn, if that continued to go north... Southern England wouldn't exist come the next morning if anything did kick off.

Lovely charts, but somehow it never does quite pan out that way eh?

Looking at today, ESTOFEX have that huge level 1 area associated with the incoming low, just off Ireland and the Bay of Biscay:

Storm Forecast

Valid: Tue 14 Aug 2012 06:00 to Wed 15 Aug 2012 06:00 UTC

Issued: Mon 13 Aug 2012 23:20

Forecaster: KOROSEC

A level 1 was issued for NW Iberia towards NW France/SW UK mainly for large hail, damaging winds, excessive rainfalls and tornadoes.

SYNOPSIS

An omega blocking pattern persists over Europe with two upper lows on its western and eastern flank. A small but intense upper low wobbles over central Ukraine while a larger upper low is located over eastern Atlantic sea. Its axis moves towards NW Iberia and W Europe on Tuesday where a deep cyclone with a sharp surface cold front takes place.

DISCUSSION

... NW Iberia into parts of W Europe ...

A well-defined DCVA will be a focus for convective activity on the western flank on the blocking area. A sharp trough is pushed from Atlantic towards NW Iberia where strong mid-level jet rounds its base and creating favorable strong shear for organized storms. 20-30 m/s of deep layer shear will result in the afternoon/overnight hours. Marginal instability will become available along the front, so expect severe storms to take place posing threat for large hail, intense rain and damaging winds. A tornado or two is also possible given the strongly enhanced LL shear/helicity just ahead of the cold frontal boundary. This threat seem maximized towards the evening hours before activity spread northwards towards UK overnight. Extreme NW France towards SW UK were also included into the level 1 area given the some threat for especially severe winds, excessive rainfalls and possibly a tornado as both SREH and LL shear remain high overnight.

UKASF:

Storm Forecast Moderate

Forecaster: Dan

Last Updated: 2012-08-13 20:54:00

Valid: 2012-08-14 00:00:00 - 2012-08-14 23:59:00

Synopsis:

Large, elongated area of low pressure over the Atlantic beneath an upper trough. A warm, humid airmass is advected northwards across Britain ahead of the upper trough, while cool mid-levels are present over northern Britain.

Discussion:

... ATLANTIC OCEAN & CELTIC SEA ...

During the early hours of the morning, a swathe of several hundred J/kg CAPE will move northwards into southern Ireland from the Atlantic. With this, it is possible that a few thunderstorms will form offshore, and may move inland to Ireland during the daybreak hours, but will probably decay/weaken during the morning hours.

... SCOTLAND, NORTHERN IRELAND, IRELAND ...

Scattered showers and thunderstorms will form as up to 1000J/kg CAPE develops in response to diurnal heating. With jet developing aloft, 30kts DLS will allow storms to become fairly well organised, with the most widespread sferics coverage expected in the highlighted MDT areas.

Low-level convergence and slight LLS may allow a funnel or weak tornado to develop, while hail locally >2.0cm in diameter is possible in any stronger cells. Slight backing of the surface winds may also allow a low-topped supercell to form.

SkyWarn have a watch out that commences from 00Z tonight:

SKYWARN UK SEVERE WEATHER WATCH #048

ISSUED: 1500UTC MONDAY 13TH AUGUST 2012

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

ALL AREAS UK

IN EFFECT FROM 0000UTC WEDNESDAY 15TH UNTIL 1500UTC THURSDAY 16TH AUGUST 2012

BISCAY LOW DEEPENS TO ~980MB INTO THE SOUTHWEST, DRIVING STRONG INSTABILITY AHEAD OF AN ACTIVE COLD FRONT WITH GALES FOLOWING

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...FLOODING...GALES...STRONGER GUSTS...FUNNELS/TORNADOES

DISCUSSION:

THERE IS ADEQUATE MODEL AND AGENCY CONFIDENCE IN A SEVERE WEATHER RISK THROUGH WEDNESDAY INTO THURSDAY TO WARRANT EARLY ISSUANCE OF A WATCH. A LOW DEVELOPS UNDER A STRONG JET CORE IN THE BISCAY AREA AND SOUTHWEST APPROACHES, DEEPENING TO PERHAPS BELOW 980MB WHICH IS UNUSUAL FOR SUMMER. A VERY WARM AND MOIST AIRMASS WILL BE ENCOURAGED NORTH FROM FRANCE AHEAD OF THIS, PROVIDING POTENTIAL FOR EXTREMELY HEAVY RAIN IN RELATIVELY SHORT PERIODS AS THE FRONT PUSHES ACROSS THE UK. ACCUMULATIONS OF UPTO 40MM LOOK LIKELY IN MOST AREAS, WITH SOUTH AND SOUTHEAST FACING SLOPES POSSIBLY HIGHER GIVEN STRONG WINDS ALONG THE FRONT. SOME CONVECTIVE INITIATION IS POSSIBLE AHEAD OF AND WITHIN THE FRONTAL ZONE, PROVIDING FOR POSSIBLE PRECIPITATION AND WIND ENHANCEMENT AS DIRECTIONAL SHEAR IS FAVOURABLE FOR ORGANISATION AND POSSIBLY FOR FUNNELS OR TORNADOES. STRONG THUNDERSTORMS IN FRANCE MAY ALSO CROSS THE CHANNEL IN THE EARLY HOURS OF WEDNESDAY AFFECTING MOST AREAS OF THE SOUTH COAST. BEHIND THE FRONT CLOSER TO THE LOW CENTRE, GALES ARE LIKELY WITH GUSTS PERHAPS EXCEEDING 60MPH, MAINLY AROUND AREAS BORDERING THE CELTIC AND IRISH SEAS BUT ALSO HIGH GROUND OF WESTERN MAINLAND UK AND EXPOSED AREAS OF NORTHERN IRELAND. THIS WATCH WILL BE UPDATED AND POSSIBLY UPGRADED

21st OWS for later tonight:

Lightning ensembles for midday:

Midnight:

Aviation weather for today:

GFS for today has some CAPE in Ireland and Scotland in daylight hours:

Rain in the North of Scotland:

Lower level lapse rates patchy, higher level can be seen sweeping into Scotland across Ireland:

Where there may be a small tornado risk mid afternoon:

Simple format GFS overview goes with some thunderstorms possible later:

Then there's tomorrow......

[Biggin]

Am liking the Skywarn " THIS WATCH WILL BE UPDATED AND POSSIBLY UPGRADED" and " STRONG THUNDERSTORMS IN FRANCE MAY ALSO CROSS THE CHANNEL IN THE EARLY HOURS OF WEDNESDAY AFFECTING MOST AREAS OF THE SOUTH COAST"

[Coast]

Am liking the Skywarn " THIS WATCH WILL BE UPDATED AND POSSIBLY UPGRADED" and " STRONG THUNDERSTORMS IN FRANCE MAY ALSO CROSS THE CHANNEL IN THE EARLY HOURS OF WEDNESDAY AFFECTING MOST AREAS OF THE SOUTH COAST"

I must admit I've gone into the other thread with tomorrows possibilities, but yes, I did get a little bit excited when reading that! I'm just not sure why the BBC/MetO are not picking up on anything - is it because there isn't anything to really comment on???

[Robbie Garrett]

Coast, well we can always hope You know what they say when we are well over due for something, it doesn't come at once, it comes like a London Bus, more than one at time.

The drought-killing rainfall all came in one go, pretty much...

NAO is currently neutral and if it is likely to stay there I am very optimistic for a storm end to August and September.

If a Euro High does build. pretty good chances of some plume weather.

Edited August 14, 2012 by Robbie Garrett

[Harry]

I must admit I've gone into the other thread with tomorrows possibilities, but yes, I did get a little bit excited when reading that! I'm just not sure why the BBC/MetO are not picking up on anything - is it because there isn't anything to really comment on???

If you run the MetO's radar forecast map, you can see why they are saying nothing. Their model seems very boring for the SE quadrant with no signs of convective activity either ahead or behind the frontal band (which itself is meh!!)

In fact, the scope for storms seems almost non existent for the UK at large on the back of these charts.

As for the charts Robbie has posted for next week, yuuuuuuuuuuuuuuuuuuuuuuuummmmmmmmmmmmyyyyyyyy!!!!!!!!!