Uk Convective General Discussion & Forecasts - May 2012 Part 2

[MP-R]

Does anyone know a website from which I could get hold of old lightning maps for the each day for the UK, i.e. going back to the early 1990s as well as the more recent 2000s and 2010s as the wetterzentrale one seems to die on December 11th 2007. Thanks.

?

[Supacell]

The great chart i posted earlier from the gfs 6z was not mirrored on the gfs 12z. However, with all that potential just a mere distance from our shores, then eventually the uk must get to join in on the fun, shouldn't it?

[Convective]

Too be honest, Monday is looking pretty good here. CAPE 300j/kg, -1LI, air temperature 6°c and dew point 5°c. Sun should be out by the afternoon aswell!

[Aaron]

Could there be some convection potential on Monday? Laura Tobin mentioned thunder this morning and NAE shows a squall-like feature running from SW Wales to NE England

Edited May 6, 2012 by Aaron

[Coast]

Could there be some convection potential on Monday? Laura Tobin mentioned thunder this morning and NAE shows a squall-like feature running from SW Wales to NE England

Maybe parts of the North West and Northern Ireland....

You have a chart for Tuesday, I think that all but peters out before it gets to us??

Generally looks quite quiet to me for a while.

[Chris.R]

Wow looks great for tomorrow. 500 J/KG CAPE and -1 LI with a southerly wind. It might be are day at last.

[Chris.R]

Met office say nothing though, they just go for a further spell of rain from mid afternoon. Strange.

[gottolovethisweather]

Wouldn't say it looks great.

Messy 12z outputs from the GFS and NAE, with the cold front and associated cloud and RF trailing across England and Wales during the afternoon likely to hamper convective potential. Can't even tell if we're looking at a post front risk as the GFS can't distinguish between what's dynamic and what's convective wrt to its precip progs INVOF the front.

weather09, sorry to trouble you but what does RF stand for and also INVOF?

Cheers

gottolovethisweather

[Chris.R]

Was looking at the 06z GFS, has probably changed on the 12z.

[Chris.R]

Yes, a bit of a downgrade on the 12z, oh well.

[legritter]

any body out there ,i need some input from all you severe weather fans ,are we heading for a monsoon this week .mother inlaw been reading papers again , iv just had a loook through charts and it looks promising this week for some seriouse rainfall totals . not been around much the last couple of days so iv missed all the info , hope we can get some convective action between fronts especialy now the sun is getting stronger ,

[Mesoscale]

you wouldn't think the sun was getting stronger around here with how chilli it has been. Hopefully it does start to get warmer soon but being so close to the coast I don't know what my chances of seeing a decent storm would be. If storms came up from france normally they weaken over the water and regain strength over land but im so close to the water I can see it out of my window. :/ im moving back t hertfordshire in a couple of weeks though so hopefully when the storms come up from the south east london will intensify them like it has done on a few spectacular occasions. Looking at the charts it looks like it will be a spotty lightning chance with the odd rumble of thunder around. My early warning detection system/dog used to alert me at night and sometimes during the day but he won't help me this year as he died in Feb I may get a few surprises this year hopefully.

[Jane Louise]

Looking good for tomorrow!

...British Isles...

The frontal system of a mature cyclone, which parks itself just off the Irish West coast, crosses these areas from the Southwest and looks capable of sparking a round of maritime convection. Insolation and diurnal warming are expected to create one or two hundred J/kg of CAPE in the warm sector, where also deep layer shear is enhanced (15 to 20 m/s) underneath the polar jet. While the bulk of a strongly helical flow will be placed ahead of the warm front, still veering wind profiles (100-200 m^2/s^2 of 0-3 km SRH) and some low-level shear (~10 m/s between 0 and 1 km) will probably persist into the warm sector. Showers and thunderstorms in this environment may turn into multicells and low-topped supercells with a chance of small hail, marginally severe wind gusts and maybe an isolated tornado. The threat is maximized over Southern England and in particular over Wales, where persistent upslope flow and a possible convective line along the trailing cold front may additionally cause excessive precipitation. A level 1 was drawn in order to reflect this combined threat.

Vertical wind shear is much weaker in Ireland in the vicinity of the vertically stacked low pressure system, which might result not only in locally excessive precipitation but also in the formation of a few funnel clouds or even landspouts. A threat level does not seem to be necessary, in particular as the center of the low pressure system remains offshore.

http://www.estofex.org/

[DubWeatherAddict]

SLIGHT upgrade for me here in DUblin on the 18z run! -3 LI and 580 cape?... SURE ILL HAVE THAT thank you very much! ... KINDA getting a TAD excited now!

Camera ready to rock. Bring it on!

[multi cellular thunderstorm]

Not too far outside the Estofext level 1 here in Nottingham, so with the lack of action here so far, I'll definitely be keeping a close eye on things tomorrow.

Hoping Nick will put out a convective forecast for Netweather too.

[Convective]

Bring it on!

[AWD]

You lucky welsh people! Lol!

TORRO include a large swayth of the Midlands in theirs too!

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

Edited May 7, 2012 by Active Weather Dude

[Supacell]

There has already been sferic across SW Wales this morning. Looks like some promise for today. I will be around the North Midlands this evening so hopefully may see something down there.

[AWD]

A tweet from my local forecaster expecting action after the main band as passed through!

Ian Fergussonâ€@fergieweather

W COUNTRY, cont'd: More heavy rain, with embedded t-storms possible, arrives into many districts (mostly N'ern/W'ern) late evening/tonight..

[Jane Louise]

A tweet from my local forecaster expecting action after the main band as passed through!

Ian Fergussonâ€@fergieweather

W COUNTRY, cont'd: More heavy rain, with embedded t-storms possible, arrives into many districts (mostly N'ern/W'ern) late evening/tonight..

Yes, I got that too. fingers crossed we all get something later

[Coast]

You lucky welsh people! Lol!

TORRO include a large swayth of the Midlands in theirs too!

Blimey, that one crept up on me, must take more notice on BH weekends!!

Almost to late to put up these charts, but here they are for info:

Ireland and Wales today then?

[Coast]

Staplehurst's UKASF forecast summing things up nicely for today:

Forecaster: Dan

Last Updated: 2012-05-06 20:36:00

Valid: 2012-05-07 00:00:00 - 2012-05-07 23:59:00

Areas Affected:

SLGT: SW Scotland, Northern Ireland, Ireland, IoM, C + E Wales, NW England, Midlands, E Anglia, SE, CS + SW England

Synopsis:

A deepening surface low under the base of an upper trough will approach and cross western Ireland during Monday. Several zones of potential convection exist.

Discussion:

Primary focus during much of the daylight hours will be across Ireland and Northern Ireland. Behind the occlusion, insolation and rising LSTs will steepen lapse rates as cold mid-levels overspread the area (-30C at 500mb), generating some 500-600J/kg CAPE. This, coupled with several lobes of vorticity will allow numerous showers and a few thunderstorms to form, and some will become slow-moving across northern parts of Ireland into Northern Ireland with lighter winds here under the trough axis.

Showers/storms will generally move in a N/NNE direction with time, but with relatively weak shear away from the South, thus convection may become rather messy and poorly organised.

However, across the southern half of Ireland, with the jet aloft, some 20kts LLS and up to 40kts DLS will allow convection to become better organised, with a heightened risk of a weak tornado forming here. Hail is likely in many of the showers, with a risk of diameters >2.0cm in any intense cores. Showers will become reduced in coverage during the evening hours as daytime heating subsides, with any sferic activity becoming gradually confined to the far north where a few hundred J/kg MLCAPE will continue into the evening hours.

Ahead of the cold front, scattered showers are also likely to develop from SW England through into the Midlands. A few hundred J/kg CAPE with cold air aloft will allow ELTs to reach -40C at times, with the potential for some sferic activity, but main concern is excessive cloudiness due to the warm sector environment and proximity to cold front may inhibit deep convection somewhat. Nevertheless, here there is a chance of perhaps some lightning activity during the afternoon and early evening, rapidly diminishing during the evening hours. Due to the surface-based nature of such showers/storms, with jet aloft and some 20kts LLS/30kts DLS, there also exists the risk of a weak tornado, with some small hail also likely in some showers.

The third area of interest is the Isle of Wight -- Wash eastwards, during the evening hours. There appears to be some reasonable inter-model support for a post-warm/pre-cold -frontal trough to enhance shower activity across northern France/English Channel during the late afternoon and evening hours, associated with a short-wave running northeastwards.

Given some 400J/kg CAPE, showers with the potential for sferic activity will form, and will move northeastwards across CS/SE England and East Anglia during the evening and first part of the night. LSTs will fall rapidly during the evening, and thus most showers/storms will become elevated, and although activity may weaken there are signs it may invigorate across East Anglia before exiting over the North Sea during the early hours of Tuesday. Due to the elevated nature of such activity, severe weather will be limited, despite some modest values of shear simulated by the models.

SkyWarn much the same:

SKYWARN UK SEVERE THUNDERSTORM WATCH #018

ISSUED: 0130UTC MONDAY 7TH MAY 2012 (GJ/SM)

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

WALES NORTHERN ENGLAND MIDLANDS SOUTHWEST ENGLAND SOUTHEAST ENGLAND

NORTHERN IRELAND WESTERN SCOTLAND

IN EFFECT FROM 1000UTC MONDAY 7TH UNTIL 0200UTC TUESDAY 8TH MAY 2012

MATURING LOW WITH AN UNSTABLE WARM SECTOR AND FAVOURABLE SHEAR FOR ORGANISED CONVECTION

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...STRONG GUSTS...FUNNELS/WEAK TORNADOES...HAIL...FREQUENT LIGHTNING...FLASH FLOODING

DISCUSSION:

THERE IS GOOD MODEL AND METEOROLOGICAL AGENCY CONFIDENCE OF A POSSIBLE SEVERE THUNDERSTORM RISK THROUGH MONDAY AFTERNOON AND EVENING. AN OCCLUDED WARM FRONT CROSSES THE UK DURING THE MORNING, STALLING OVER SCOTLAND BY END OF THE AFTERNOON, WITH THE LOW CENTERING OVER IRELAND. NEAR THE CENTRE OF THE LOW, STEEP LAPSE RATES WILL AID STRONG CONVECTION AND SLOW MOVING THUNDERSTORMS PERSISTING INTO WESTERN SCOTLAND THROUGH TO LATE EVENING WITH LOCALISED ACCUMULATIONS OF UP TO 20MM IN SHORT PERIODS. ACROSS WALES AND SOUTHWEST ENGLAND, PERSISTENT OROGRAPHICALLY TRIGGERED CONVECTION MAY LEAD TO SUCCESSIVE PERIODS OF HEAVY RAIN WITH SIMILAR ACCUMULATIONS BY THE END OF THE PERIOD. LOW LEVEL SHEAR ACROSS THESE AREAS, ALONG WITH THE MIDLANDS AND NORTHERN ENGLAND, WILL INCREASE THROUGH THE DAY WITH CONVERGENT SURFACE WINDS BECOMING THE FOCUS FOR STRONGER CONVECTION INTO THE SECOND HALF OF THE AFTERNOON AND EVENING, POSSIBLY ORGANISING STORMS AND MAXIMISING THE CHANCE OF DETAILED THREATS. DEEP LAYER SHEAR INCREASES DURING THE PERIOD WITH THE DIVERGENT NOSE OF A CYCLONIC JETSTREAM PUSHING ACROSS THE WARM SECTOR ALONG WITH INCREASING MID TO UPPER LEVEL LAPSE RATES, SUPPORTING STRONGER AND SUSTAINED CONVECTION PARTICULARLY FOR WALES AND THE MIDLANDS. ACROSS THE SOUTHEAST OF ENGLAND, CONVECTION INITIATED OVER NORTHERN FRANCE MAY DEVELOP AND TRANSIT AS A CLUSTER OF STORMS DURING THE EVENING. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY. THIS WATCH MAY BE UPGRADED.

[Stuart]

look like i going missed out

[DeepSnow]

Nice to be in the level one for estofex, though on its southern edge! Its very cloudy here with some moderate-heavy rain earlier, so im not sure how well today will go with all this cloud :S

Edited May 7, 2012 by DeepSnow

[Kain]

Finally some for Blizzard and I!! Im in the 1 zone on Estofez and smack in the zone on Torro woohoo could be a good day.

Bring it on I say, damp squib here we come

Edited May 7, 2012 by Kain