Storm & Convective Discussion - 01/03/15 onwards

[A.J]

NMM 06z out, and broadly the same as the 00z run.....it does show very little/no ppn on the ppn charts but I always take those with a large pinch of salt....again, 1000j/kg of both SB&MLCAPE progged during the afternoon/early evening for the west country & central/southern Eng, high lapse rates, a finger of higher PWAT values (basically a marker of precipitable water in the atmosphere) along the M4 corridor coinciding with surface wind convergence in that area to give a little extra forcing.......I'd take a stab (given the current NMM) that if there are any storms, they might initiate over higher ground over the west country (Mendips/Cotswolds) drifting ENE along the upper winds.........I'd be interested to see Nick F's & W09's thoughts when they're on later

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This Corpus Christi livecam is amazing right now... Strobe Lightning crazy rain and mad windy!

Sound too!

http://www.cctexas.com/customer-service-center/bayfront-webcam/index

[Mapantz]

Ample ingredients on the charts, but not much of a trigger! Still a risk of something isolated though.

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Convectiveweather issued an ISOL for Home Counties for tomo:

http://www.convectiveweather.co.uk/forecast.php?date=2015-04-15

[StormChaseUK]

Very warm here in Saint Malo today, reached 27-28c

 

Will keep you guys posted if any storms form over the next 48 hours.

 

[Spikecollie]

Very warm here in Saint Malo today, reached 27-28c

 

Will keep you guys posted if any storms form over the next 48 hours.

Yep, 28c here in Limousin. T-storms progged for Thursday! Woohoo!

[Nick F]

Yep, ridge across the south looks likely preventing storms developing across southern counties where diurnal surface-based CAPE is indicated to build, though sea breeze convergence inland from the south coast against the mean slack NWly flow further north means an isolated heavy shower or even thunderstorm can't be ruled out with the heat of the day. Isolated risk Weds night of thundery showers across the far SW creeping up from France from mid-level Ac convection and again during Thursday. But risk is too low for me to issue a storm forecast.

Edited April 14, 2015 by Nick F

[Harry]

BBC last night and the Metro this morning talking about risk of an isolated thunderstorm or thundery showers (respectively).

 

There was an impressive storm last year (early June?) in the Reading area which blew up under fairly dominant High pressure conditions, but those occurrences are fairly rare for the UK (and it was June with a lot more heat/moisture on tap).

 

Not anticipating much today, although the site of a nice Cb (even if distant) would be nice...haven't seen nice convection for what seems like months and months

[Tom Jarvis]

Up near Oxford for work today currently no sign of any clouds in the sky at all very nice 25c already

[StormChaseUK]

22C now in Saint Malo, 2C higher today than this time yesterday (yesterday max around 27C) 

 

Humidity also higher, so possible scattered showers later which may push up into SW UK into tomorrow.

[Nick L]

Up near Oxford for work today currently no sign of any clouds in the sky at all very nice 25c already

 

I think that thermometer is a bit off!

[A.J]

Not really convinced, AJ.  Ridge aloft overlapping region of marginal CAPE (per GFS) looks to prevent deep convection occurring, indicated by lack of anything breaking out during afternoon to early evening period on recent model outputs. Noticed the GFS does, however, break out shower activity toward SW coast during night and into early hours Thurs as heights slowly recede southward, so perhaps potential there. 

 

 

Yep, ridge across the south looks likely preventing storms developing across southern counties where diurnal surface-based CAPE is indicated to build, though sea breeze convergence inland from the south coast against the mean slack NWly flow further north means an isolated heavy shower or even thunderstorm can't be ruled out with the heat of the day. Isolated risk Weds night of thundery showers across the far SW creeping up from France from mid-level Ac convection and again during Thursday. But risk is too low for me to issue a storm forecast.

 

Bugger!.......thanks for your summaries though chaps 

BBC last night and the Metro this morning talking about risk of an isolated thunderstorm or thundery showers (respectively).

 

There was an impressive storm last year (early June?) in the Reading area which blew up under fairly dominant High pressure conditions, but those occurrences are fairly rare for the UK (and it was June with a lot more heat/moisture on tap).

 

Not anticipating much today, although the site of a nice Cb (even if distant) would be nice...haven't seen nice convection for what seems like months and months

nice to see you out of hibernation H! 

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I'm still clinging on to the storm possibility for later... :-P

[Harry]

Bugger!.......thanks for your summaries though chaps 

nice to see you out of hibernation H! 

 

Indeed, this nice plume of warmth has definitely woken me up! 

 

Absolute stunner of a day today, as was yesterday. Will be surprised if somewhere across the South doesn't exceed 25C today (according to the Met Gravesend leading the way at 24.6C)

 

Bit of a disappointing start to the year convection wise...very little in the way of 'April showers' in these parts and with High pressure dominating for the foreseeable, could certainly be very shower-less.

 

Still, as an opener, if this year turns out to be anywhere near as thundery as last year for my area I'll be one extremely happy chappy

[Flash bang flash bang etc]

Hey I think there might actually be something stirring in the channel... Rain radar picking up bits and pieces ... Then again they might just be Russian warships

[A.J]

Not this time. 

 

'Tis anaprop.

what about overnight tomorrow night mate?.....I've only had the briefest of glimpses at the 12z NMM but it does show isolated elevated storms breaking out in southern counties?

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Not this time.   

 

'Tis anaprop.

What's anaprop again? I knew once...

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Still unconvincing (lol). Having said that, with slight erosion of 500mb heights, looks like there might be a short time frame during period in question for elevated showers/possible storm(s) to develop and drift slowly north to affect southern coastal areas (possibly further inland) in advance of weakening cold front (frontal wave) currently moving south, which looks to shift region of steep lapse rates/moisture away around 00Z. So an increased risk on today, but wouldn't be too optimistic.  

 

http://www.theweatherprediction.com/habyhints/247/ 

Gotcha. Fanks :-)

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This forecast for tomo courtesy of convectiveweather:

Day 2 Convective Outlook

VALID 06:00 UTC Thu 16 Apr 2015 - 05:59 UTC Fri 17 Apr 2015

ISSUED 21:00 UTC Wed 15 Apr 2015

ISSUED BY: Dan

... S ENGLAND, CHANNEL ISLANDS ...

The upper low over Iberia continues to push some upper forcing northwards towards northern France and English Channel regions. There is potential, given a tongue of mid-level instability, for a couple of elevated showers (or thunderstorms) at the beginning of the forecast period over the English Channel/Channel Islands etc, although a fairly low point probability (20%).

This area of mid-level instability remains present across southern counties of England, the English Channel and northern France throughout the day, but with little in the way of trigger to encourage destabilisation. However, a shortwave trough is expected to cause some destabilisation across northern France during the afternoon, this then drifting a little farther north across the English Channel and into southern coastal counties of England through the evening. Current thinking is there could be a few scattered high-based showers/thunderstorms developing over the English Channel late in the day tomorrow and through tomorrow evening, perhaps a few more developing inland for a time, before the surface cold front sinks southwards through the early hours of Friday. In fact, given some slightly better upper support, there does appear to be a better chance of this occurring than Wednesday evening/night`s potential convection. Can`t rule out isolated showers/storms from AcCas across the ISOL during daylight hours, but best potential (albeit still limited) appears to be through the evening hours.

---

And looking good at the moment in the channel - some rain showers developing and the odd sferic showing up... :-)

[A.J]

some mid level instability around here this morning......some Ac Cas drifting up from the SW trying to tower but not succeeding at the moment.....not expecting anything of note, but it's nice to see anyhoos.....

 

just seen the above forecast from convectiveweather.co.uk.....just realised it's the rebranding of the old UKASF site, nice to see them up and running again

[Flash bang flash bang etc]

some mid level instability around here this morning......some Ac Cas drifting up from the SW trying to tower but not succeeding at the moment.....not expecting anything of note, but it's nice to see anyhoos.....

 

just seen the above forecast from convectiveweather.co.uk.....just realised it's the rebranding of the old UKASF site, nice to see them up and running again

Yeah - for the last year they have had a severe storm warning in place for most of the UK... :-D

[A.J]

a few sharp showers breaking out over the south Irish Sea and into North Devon...elevated in nature.....in a line arching through the south irish sea, into north devon and away to the south coast (a few echoes showing up nr Southampton/IOW).....very hit and miss though

[A.J]

et voila....first storm fires near Bideford, North Devon

Edited April 16, 2015 by ajpoolshark
sorted out my caps lock button

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So looking good for the southern coasts for later this evening and tonight?

Lovely looking skies - I think Ac Cas is my favourite type of cloud :-)

[Mapantz]