Convective / Storm Discussion - 14th May 2014 onwards

[Supacell]

Met Office now have the thunderstorm symbol over Derby for 1pm. The latest BBC forecast online now mentions thunder and thunderstorms several times for today, tomorrow and later Wednesday.

[lassie23]

Met Office now have the thunderstorm symbol over Derby for 1pm. The latest BBC forecast online now mentions thunder and thunderstorms several times for today, tomorrow and later Wednesday.

About time!

[tara303]

What's the chances for Eastern Ireland? Are we out of the risk area as usual...

I'm out here in the wild west, wondering if we'll get lucky too lol!

[Candice]

SkywarnUK have issued a watch :- SKYWARN UK HAS ISSUED A WATCH FOR SEVERE WEATHER AS FOLLOWS:BRIEF, POTENTIALLY DAMAGING TORNADOES - SOUTHERN,WESTERN, NORTH WEST ENGLAND, SOUTH WEST SCOTLAND.BRIEF, POTENTIALLY SEVERE THUNDERSTORMS MIDLANDS, SOUTHERN, WESTERN NORTH WEST, SOUTH WEST ENGLAND AND CENTRAL SCOTLANDFLASH FLOODING - SOUTH WEST ENGLAND AND SOUTH WALES

 

More details can be found here http://www.skywarn.org.uk/current.html

[Mokidugway]

First rain shower over chorlton Manchester , sky becoming increasingly threatening very humid , my wife's flying back from spain today, she could be in for a bumpy ride !!!....

[Nick F]

THERE IS A RISK OF THUNDERSTORMS FORECAST

 

Synopsis
A deep upper trough over the E Atlantic extends south from Iceland towards NW Iberia during the forecast period, with a blocking high pressure system over NW Russia/Scandinavia. Warm Air Advection (WAA) ahead of the trough to the west continues to spread relatively warm and moist air north across western Europe including mainland UK, with a gradual destabilisation across the north and west today, ahead of cold front lying across western Scotland and south through the Irish Sea/east coast of EIRE/N Ireland.

... SW ENGLAND, WALES, N MIDLANDS, N ENGLAND, SCOTLAND ...

Plume of relatively warm/moist air noted at 850mb on midnight radiosonde ascents spreading north across mainland UK has destabilised this morning across on western edge of the plume, with elevated storms in last 3-4 hrs across SW England, Wales, N England and E Scotland, as increasingly colder air between 500-300mb overspreads from the west in association with upper trough to the west. These storms may continue to bring a risk of localised flooding and cloud-to-ground lightning across parts of northern and western Wales, IoM, east coast of N Ireland and NE Scotland over next few hours before gradually clearing away north and easing.

Airmass is then expected to stabilise later this morning and through the early this afternoon, before destabilising later again from the SW, as upper flow increases and heights/surface pressure begin to fall, increasing ascent of warm moist plume, so there will be a risk of further heavy showers and some isolated elevated storms breaking out across the far SW England and Wales by the evening ... also isolated heavy showers and thunderstorms may break out across the southern uplands of Scotland and over the Pennines, in response to surface heating and upslope ascent of easterly flow.

... S ENGLAND and WALES Monday night ...

Some elevated thunderstorms may push up from N France into the above areas in the early hours of Tuesday morning, as forced ascent increases with approach of a shortwave trough in the upper flow moving north and arriving across SW/S England overnight and cold front moves in from the SW Tues morning. With increasingly strong upper flow and deep-layer vertical shear - any storms may organise into mulitcell structures bring a risk of flash-flooding, hail, gusty winds and frequent cloud-to-ground lightning.

Full forecast can be found here: http://www.netweather.tv/index.cgi?action=convective;sess=

Edited May 19, 2014 by Nick F

[Biggin]

couple of heavy showers forming in the channel heading exeter torquay way.

Edited May 19, 2014 by Biggin

[Lauren]

Hmmmmm, I am far too near the edge of the risk for my liking.

[paul m]

First rain shower over chorlton Manchester , sky becoming increasingly threatening very humid , my wife's flying back from spain today, she could be in for a bumpy ride !!!....

IS THAT WHEN SHE GETS HOME!!!!!!!!!!!

[Jane Louise]

With all these warnings appearing I must say I'm feeling more positive now. I have been rather baffled this morning as to what is going to happen and felt that it was all maybe over hyped. Seeing these warnings have cheered me up and here's to wishing everyone good luck and may me and all of you  get a storm.  Looking forward to your pics and reports.

[Mapantz]

Looked busy across Wales this morning?!

[NO LONGER POSTING]

Boom! Looks like we could get some juicy imports!

[Mapantz]

The MetOffice app shows nothing more than a few rain showers here.

It is the opposite on Netatmo and Weatherpro, they've issued a level one and two warning..

[Nick F]

With all these warnings appearing I must say I'm feeling more positive now. I have been rather baffled this morning as to what is going to happen and felt that it was all maybe over hyped. Seeing these warnings have cheered me up and here's to wishing everyone good luck and may me and all of you  get a storm.  Looking forward to your pics and reports.

 

Always difficult to forecast storms in the UK compared to other parts of the world, though I do think warnings of supercells and tornadoes maybe going a little far based on current charts and analysis, storms coming up from the south across the west  and tonight across the south/southwest UK will be mostly elevated - so will not pose a severe threat other than localised flooding/CG lightning ... storms may pop up this afternoon, but not widespread as suggested by GFS CAPE charts, they appear most likely to form over the higher ground of the Pennines/southern uplands Scotland this afternoon - which  may bring some flash flooding problems given fast run-off ... though not say there won't be a few isolated storms popping up elsewhere with the heat of the day.

Edited May 19, 2014 by Nick F

[Mokidugway]

IS THAT WHEN SHE GETS HOME!!!!!!!!!!!

oh paul !!!!.......

[NO LONGER POSTING]

Looks like its go in the channel!

[Mokidugway]

I would be lucky to hear any thunder , planes coming in to land at Manchester are so loud today !!...

[Jane Louise]

Always difficult to forecast storms in the UK compared to other parts of the world, though I do think warnings of supercells and tornadoes maybe going a little far based on current charts and analysis, storms coming up from the south across the west  and tonight across the south/southwest UK will be mostly elevated - so will not pose a severe threat other than localised flooding/CG lightning ... storms may pop up this afternoon, but not widespread as suggested by GFS CAPE charts, they appear most likely to form over the higher ground of the Pennines/southern uplands Scotland this afternoon - which  may bring some flash flooding problems given fast run-off ... though not say there won't be a few isolated storms popping up elsewhere with the heat of the day.

Thank you for the explanation Nick.Going to take my dog across the fields  to look at any cloudscapes that may be an indication for later around here.

[Harry]

What do you reckon the chances for us in the SE Nick?

 

Obviously, both your forecast along with those from the mainstream forecasting sites (ie Estofex) including the SE in the forecast zones but I can't see it myself with 'west being best' - anything there which should keep my interest alive?

Edited May 19, 2014 by Harry

[lorenzo]

Looks like a fun day ahead, decent CAPE values picking up from 1400 onwards. Handy site for soundings etc http://rasp.inn.leedsmet.ac.uk/RASPtableGM/RASPtableGM.html

 

Best weather yet for up here having remained with the junk spewed off the low passing North over the weekend and a definitive divide from clear skies and a grey blanket of doom.

Best of both worlds nice and hot or potentially for the odd bang later this afternoon. 

 

Here's a vid of the cell that skirted the East Coast of Scotland last night before landing on Peterhead to give a nice night time show of sferics.

 

http://cameo.tv/c/dvHTk2ub

[Bobby]

Had no idea there were so much activity in Wales early this morning, not a drop of rain last night. Might have been some distant lightning and thunder that I slept through,  seems it mainly passed to the West. Anyway lets hope we get hit today, looking fairly promising.

 

Currently calm with spells of sunshine and a lot of altocumulus castellanus and higher level cirrus/cirrostratus.

[Nick F]

What do you reckon the chances for us in the SE Nick?

 

Obviously, both your forecast along with those from the mainstream forecasting sites (ie Estofex) including the SE in the forecast zones but I can't see it myself with 'west being best' - anything there which should keep my interest alive?

 Difficult to say other than a broad zone of potential overnight across S/SE England, these situations it's best to nowcast :-)

[Mokidugway]

Clear sky's now albeit hazy temperature climbing now ,insolation should start pushing stuff up soon , well I hope so it would be a waste of a day off !!!....

[Liam J]

Warm and humid here already up to 20c with some high level cloud. The activity that was over Wales earlier has passed well to the west heading into N Ireland. Hoping for some action later

[BrickFielder]

Today 

Its a little bit complicated to forecast whats going to happen over the next few days. Looking at a forecast SkewT for today a couple of things show up. Firstly that low level moisture is not that deep which means instability (CAPE) is probably over stated on the charts. Secondly that top level lapse rates (no chart for this) are not that great, which means cloud tops may be a little limited. So not that impressed with storm opportunities today.

 Overnight we have a cold front approaching ( looking at UKMO Fax charts) swinging into the south of the UK. Ahead of this is just a suggestion of a trough. This might suggest some elevated storms ahead of this overnight.

Forecast SkewT's suggest rather meagre instability which will be elevated rather than surface based.

There is also the possibility that the front becomes convective itself especially into tomorrow where it would tend to effect areas further north.

Tomorrow

 

I rather like the look of the storm potential tomorrow, but I think cloud cover may play a part. Looking at a forecast SkewT then we can note that instability is not so much reliant on shallow low level moisture. Upper level lapse rates are high meaning cloud tops can reach quite high.

The Uk comes under the nose of a high level jet streak, with a little divergence aloft.

 

 

There seems to me just enough wind speed shear through the mid levels for some updraft downdraft seperation. Low level winds are light and although there is not much wind speed shear between the surface and cloud bases winds might be light enough for any storm to develop its own winds. Weak directional shear and low level shear could limit severity. Over All I am still not convinced about tomorrow and am worried about cloud cover. Its still too early to really forecast at the moment so its just initial thoughts at the moment.