Convective / Storm Discussion - 30th March 2014 onwards

[Supacell]

Estofex appear to have two similar but differing forecasts for today 

[Arnie Pie]

Nice one W09... Was wondering what was causing the 40 odd percent storm risk over our area for the early hours

Edited April 5, 2014 by Arnie Pie

[Nick F]

Potential for an eastward-moving squall line to develop across England and Wales tomorrow along cold front moving in from the west. 

 

 

Strong jet parallel to front and veering winds towards the surface will create fairly strong deep layer shear, couple this with a fairly steep dew point/temperature gradient along front and large scale forced ascent - ingredients for a squall line to develop. GFS is indicating a few 100 j/kg  or more CAPE ahead of cold front across E Wales, central and eastern England early to mid-afternoon.

 

Main risk from the potential squall will be strong wind gusts to 50-55mph, perhaps a few cgs and intense rainfall leading to localised flooding. Given marked low-level veering of winds indicated with passage of front, there is a low risk of a tornado with any broken line segments that form along front or tail-end charlie - where inflow is not disrupted so much by the outflow of linear cells. 

Edited April 6, 2014 by Nick F

[vladthemert]

thanks nick love the possible weak tornado development with this.  I hope so always wanted to see one for real but not damaging one though.  Might get some action here finally .  Got some strange wet stuff through the night 3.3mm.   Forecast on met red, purple band heading here around roughly 5pm.   Lightening wizard has this potential to drop 20-38mm  rainfall and some hail activity.

[Mapantz]

thanks nick love the possible weak tornado development with this.  I hope so always wanted to see one for real but not damaging one though.  Might get some action here finally:yahoo: .  Got some strange wet stuff through the night 3.3mm.   Forecast on met red, purple band heading here around roughly 5pm.   Lightening wizard has this potential to drop 20-38mm  rainfall and some hail activity.

The Euro 4 accumulation chart suggests minimal totals in the east over the next 24 hours, larger totals west/south west.Similar story from the NMM..Nice radar loop.

[vladthemert]

thanks mapantz suggesting we miss out again 

[Mapantz]

thanks mapantz suggesting we miss out again:( 

Don't take those maps at face value, they're only a guide, you never know though, you could get something interesting.

[Summer Sun]

Met office text forecast for tomorrow

 

Monday:

 

Mainly dry start in the north. Rain, heavy at times, in central and southern areas clearing gradually eastwards. Clearer, brighter conditions follow with showers, some heavy, mainly in the west

[vladthemert]

cheered me up mapantz  this was posted on weather forum link to website if mods unhappy just delete.  He updated it show possible location for tornado risk.

 

http://www.ukweatherworld.co.uk/forum/index.php?/topic/102964-convective-outlook-mon-7th-april-2014/

[Mapantz]

The radar went downhill quickly..

[Supacell]

A level 1 from Estofex for East UK tomorrow.

 

 

They are saying (relating to the UK)

 

Incoming wave still offers a neutral or even a slightly positive tilt, which raises concerns about warm sector quality in respect of CAPE-build-up. Combination of rich BL moisture and neutral mid-layer lapse rates should keep the atmosphere in the proximity of breaking the cap, although GFS favors an even strenghtening cap around noon with faint warming of the 850-700 hPa layer. Therefore, isolated and elevated thunderstorm activity proceeds the cold front and affects the warm sector until noon. Nothing severe is forecast .
Focus for enhanced convection remains along the eastbound moving cold front, which crosses E/SE-UK during the late afternoon/evening hours. Cooling mid-layers and incoming forcing (synoptic-wise and due to the front itself) with rich prefrontal moisture probably assist in 200-500 J/kg MLCAPE along the front. Strong 0-6km bulk shear in excess of 20 m/s, enhanced BL shear (directional and speed shear) and low LCLs cause a wind gust and isolated tornado risk mainly with more discrete cells ahead/along the cold front. Marginal angle of the deep-layer shear vector to the front keeps the risk of longer-lived discrete structures low however. As the cold front leaves the forecast area to the east around sunset, thunderstorm probabilities drop rapidly from W to E. 

 

http://www.estofex.org/

 

It's looking interesting tomorrow with a possible squall line developing and pushing east, across my area at some point in the afternoon. ScottRichards10 said earlier that it looks similar to the 25th January and I would be inclined to agree with this. It may not be the same reasoning (i can't remember the forecast behind the 25th squall) but the results could be very similar. If so I would be very happy as that produced a great little storm over Derby.

Edited April 6, 2014 by Supacell

[Nick F]

Storm & Convective Forecast

 

Issued 2014-04-07 09:01:42

Valid: 07/04/2014 0900z to 08/04/2014 0600z

 

 

THERE IS A RISK OF THUNDERSTORMS FORECAST

 

Synopsis

Upper trough will shift eastward across the UK/Ireland today, ahead of it - a waving cold front will shift NE across England and Wales, with an area of low pressure in the wave deepening as it moves toward NE England and out into the N Sea this afternoon.

... ENGLAND AND WALES ...

Height falls with approaching trough will lead to large scale ascent of rich surface moisture advecting NE in warm sector across England and Wales this morning, bringing widespread rainfall with some embedded convective activity, strong enough to bring some isolated thunderstorm activity, with the risk of some torrential downpours leading to localised flooding.

Then the attention turns to this afternoon, when approaching upper trough from the west introduces increasingly cold and dry air aloft - which will serve to increase lapse rates and thus instability across the warm sector ahead of the cold front. GFS develops a pool of 200-500 j/kg CAPE from midday ahead of the cold front moving east. Strong jet stream winds parallel to the cold front and backing winds towards the surface will bring deep layer shear in the order of 40-50knts ... which will allow any storms that develop in increasingly unstable environment to organise into a squall line feature along the cold front with perhaps more discrete storms forming ahead of the front - capable of bringing strong wind gusts (up to 45-55mph), hail, cloud-to-ground lightning and torrential rainfall leading to flash-flooding. Furthermore, low LCLs (lifted condenstation level) of around 200-400m along with strong low-level shear with passage of cold front and ahead of wave low moving NE will enhance the potential risk of a tornado forming with strong updrafts in any of the more discrete storms. Therefore, have issued a SLIGHT risk.

Edited April 7, 2014 by Nick F

[Jane Louise]

And here's hoping once again Cheltenham doesn't miss out either Lol. It's going to be an exciting day again. Good luck all.

[Nick F]

Further to the forecast above, fax shows a split cold front feature which can be clearly seen on the current radar too:

 

 

Radar shows the two distinct areas of rain along the fronts across the north and west and also across the SE corner down into Normandy.

 

 

[Dancerwithwings]

Nick, I just love the way you make things sound so interesting & dramatic!!!

 

Strong wind gusts (up to 45-55mph), hail, cloud-to-ground lightning and torrential rainfall leading to flash-flooding. AND WAIT FOR IT...Furthermore....

The potential risk of a tornado forming with strong updrafts  WOW!!!...... BUT THEN.... Therefore, have issued a SLIGHT risk.

 

Love it! All that for a Slight risk  Can't wait till there's a high risk Be like reading armageddon... lol

Edited April 7, 2014 by Dancerwithwings

[vladthemert]

thanks nick and supercell.  I apreciate your posts.

 

GFS dont think it will be severe so there disagreement time will tell if its level 1 or not.   Been windy here and quite downpour this morning as the tail came through.   So excited to be in the slight region of this.  Could we finally get some action..  

 

By the way poster on the forum to my link moved tornado risk further north derby area to peterhead and width to the east coast looks like.  Interersting if we do get something where it will hit.

[Summer Sun]

So far we've managed to avoid the worst of the rain here in Darlington nothing worse than a bit of drizzle so far

 

The Darlo rain shield is working at its best this morning

Edited April 7, 2014 by Summer Sun

[vladthemert]

So far we've managed to avoid the worst of the rain here in Darlington nothing worse than a bit of drizzle so far

 

The Darlo rain shield is working at its best this morning

 

Darlo new english riviera Summer Sun, better not tell torquay.   This morning gods caught up our shield collapsed..  We had 2 days rainfall that we had whole winter though winter did not produce much rainfall so not hard to do.  It was sorely needed mind.

 

Winds been slowly increasing The clouds moving quickly through.

[Boro Snow]

Gavin I'm sure things are about to change

[Andy Bown]

Looking at the radar and lightning detector it seems today may be the first 'Kent Clipper' of the year!

[Mapantz]

Dorset found all the gaps again.

[Summer Sun]

Another band of rain which looked like it was going to hit has gone north of Darlington its amazing how we can often miss the rain yet 10 miles or so up the road it hits

[vladthemert]

Another band of rain which looked like it was going to hit has gone north of Darlington its amazing how we can often miss the rain yet 10 miles or so up the road it hits

 

we do the same normally here, we look too missed the worst.  Although meteox has smallish heavy cloud in the firing line later.  Looks like worst is in channel and france.  Acording to meteox you have had 1 lighting strike near your location Summer Sun can you confirm.

[Summer Sun]

we do the same normally here, we look too missed the worst.  Although meteox has smallish heavy cloud in the firing line later.  Looks like worst is in channel and france.  Acording to meteox you have had 1 lighting strike near your location Summer Sun can you confirm.

 

I haven't saw any lightening so I'm unable to confirm, the netweather lightning detection doesn't show anything for this area

[vladthemert]

thanks summer sun likely blip error.