Storm & Convective Discussion April 2016 Onwards

[Liam J]

Time for a new thread as we're nearly halfway through spring with summer just around the corner.

Storm & convective discussion for the UK & Ireland, if you want to discuss storms across the rest of Europe there's a thread here.

Unhappy with the lack of storms in your area? There's a thread here if you want a moan.

Old thread here.

 

Edited April 11, 2016 by *Sub*Zero*

[Flash bang flash bang etc]

In there first!

:-D

[alexisj9]

Completely clouded over here now, don't know if that's good or bad. Feels chilly out and humid in.

[Speedway Slider]

The "click heres" don't seem to work on the old thread...

 

[Flash bang flash bang etc]

Overcast here but the sun is beginning to make an appearance. Warm-ish though so it's all still to play for. Wind direction and activity in France seems to be favouring my area at the moment but how much influence will our chilly channel have on proceedings? Only time will tell... :-D

[Speedway Slider]

Closed in here in Leicester now, temps dropped from 16c to a chilly 13c, but it has a clammy/humid/dank feeling to it, if you know what I mean.....

[alexisj9]

Raining now started with big drop but has modified to normal drops as it got a bit heavier, no thunder heard or lightening seen as yet.

[Stormyking]

Referring to Mapants quote to me in the last thread, I think there is a risk of showers here around Mid morning but i think they will be fairly light - moderate in nature  Middle of the Island may develop its own afternoon shower if we can create our own land warmth which is very common on the island too! Though the main interest is definitely North Devon and Dorset.

Lets see what the 12z brings!

[Raidan]

With Bristol getting a mention im quite interested in seeing what tomorrow brings though if anything hope its after 2pm when i finish work.

[tornadomanuk]

Interesting little cell now fired up over Exmoor according to the radar. Wonder if anything electric will come of it!

[alexisj9]

Looks like France is starting to wake up now, still not holding my breath that it will get here. Still cold cloudy with patches of rain, with some mist in between.

[Flash bang flash bang etc]

Anyone confused by the direction of those showers over France?

seem to be going all over the place!

[Mapantz]

5 minutes ago, Flash bang flash bang etc said:

Anyone confused by the direction of those showers over France?

seem to be going all over the place!

Overlay the wind vectors at 500 or 850hpa- good way to to see what's going on.

[Spikecollie]

28 minutes ago, alexisj9 said:

Looks like France is starting to wake up now, still not holding my breath that it will get here. Still cold cloudy with patches of rain, with some mist in between.

I'm in Limousin, mid/southwest France. The best storm was about 1730 this evening. Most notable by the incredible winds that came with it and the daytime darkness, but also some thunder and IC lightning. Most of the storms will probably be to the north for late evening and night. Plenty of activity to come over the following days...

[William Grimsley]

There's some lovely thunderstorms over on the continent, if only the English Channel was land, then we'd have some great thunderstorms here. LOL. Tomorrow is looking good for areas north of me, but unfortunately I can't chase. Thursday Night, Friday, Saturday and Monday look very convective for my area. Something to watch.

Edited April 11, 2016 by William Grimsley

[Convective]

More interest in the days to come as the advection of continental-based energy continues to make its way towards Britain. Not too bad with the energy in the next few days, considering we're in early April. More disappointing are the 850 temperatures and dewpoints. Not much in the way of strong winds aloft either so anything that does develop would be likely to be fairly localised although potentially relatively strong as they root into the boundary layer where surface temperatures are more favourable.

[Spikecollie]

Just wanted to say: I know there's a thread for European storms not affecting the UK, but sometimes folks want to know what's happening on the near continent so that they can inform their own storm awareness and anticipation of what may and may not make it across the channel etc.. I'm in an interesting meteorological position here, getting land generated storms and those that come from the Bay of Biscay.

I'll always report objectively, and any purely continental mainland storms I'll report in the appropriate thread...

[A.J]

as it's quiet (relatively speaking in this thread this time of year) you're more than welcome to post your stormy goodies in here so we can all get our fix 

[Spikecollie]

3 minutes ago, ajpoolshark said:

as it's quiet (relatively speaking in this thread this time of year) you're more than welcome to post your stormy goodies in here so we can all get our fix 

Cheers! All hoping for t-storminess on both sides of the channel, shared if possible.

[Greeny]

Mainly indoors but its feeling warm and muggy for the first time for me this year. Raining a little outside. I much prefer this to the cold thats for sure.

[East_England_Stormchaser91]

9 minutes ago, Greenday said:

Mainly indoors but its feeling warm and muggy for the first time for me this year. Raining a little outside. I much prefer this to the cold thats for sure.

Definitely with you on that one. There's a muggy feel to the air tonight. Which in my view is welcomed in open arms! Just started raining here with convective drops. 

This weather setup is by far my favourite in the UK by a mile, even more so when all the right parameters are in place. Low pressure cut off to the SW scooping up unstable muggy air from the SSE is the best recipe for those proper thunderstorms. Not what we saw last week! 

[alexisj9]

16 minutes ago, East_England_Stormchaser91 said:

Definitely with you on that one. There's a muggy feel to the air tonight. Which in my view is welcomed in open arms! Just started raining here with convective drops. 

This weather setup is by far my favourite in the UK by a mile, even more so when all the right parameters are in place. Low pressure cut off to the SW scooping up unstable muggy air from the SSE is the best recipe for those proper thunderstorms. Not what we saw last week! 

You think it's still on for later then, or do you mean tomorrow.

[East_England_Stormchaser91]

6 minutes ago, alexisj9 said:

You think it's still on for later then, or do you mean tomorrow.

May see the odd spark over E Anglia with that stuff exiting the Benelux, chances are pretty low I'd say though. Tomorrow looks like the interesting day. More opportunities by the looks of things further into the week too. 

[weather09]

Trouble is we're not actually drawing up any warmth/moisture of note from the south. Yesterday and today saw modest theta-w environment in the low to mid levels advect across the country (which destabilised off SW coast and over Cornwall with aid of sharpened upper trough/large scale ascent and cold front), which has now moved away to the NE. The potential over the next few days is going to be diurnally-driven, where instability is generated via heating of landmass under cold air aloft, creating steep low-mid level lapse rates and low-end CAPE.  Certainly no advection of deep moisture sourced from far south/SW for the short term. For that, we'd need to see a more robust ridge develop northward over SW/central Europe, building heat over the continent and putting a more negative tilt on the upper trough to the west. The GFS and ECM appear to be modeling this sort of upper pattern post-T144- remains to be seen if that theme will continue. 

Tomorrow sees another low risk for southern half of the UK, with focus on Midlands south where clearing skies allows for the sun to get to work during the day, which looks to build a few 100j/kg CAPE mid-late afternoon per latest modeling.  Very little movement aloft and non-existent shear, so another day of slow-moving, 'pulse' convection. Light, converging sfc winds likely focus for deep convective/storm activity, but anywhere where heating is maximised can see convection develop into showers/storms. Strongest storms likely to bring a hail (given steep lapse rates) and gusty wind threat. 

Edited April 11, 2016 by weather09

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Tue 12 Apr 2016 - 05:59 UTC Wed 13 Apr 2016

ISSUED 20:28 UTC Mon 11 Apr 2016

ISSUED BY: Dan

Omega Block over NW Atlantic maintains a broad upper low west of Biscay, extending towards the British Isles through Tuesday. The associated cold mid-levels combined with diurnal heating will generate 300-500Jkg-1 CAPE. Forecast profiles are quite dry, and convective initiation will be heavily reliant on low-level wind convergence (from sea breeze and topographical effects), hence even within the broad SLGT there will be a good deal of dry weather still in many places with showers generally well-scattered and focussed over small areas.

Scattered showers and a few thunderstorms will develop, particularly from late morning and moreso through the afternoon and into the evening, capable of producing hail locally bigger than 1.0cm in diameter in any stronger cells. DLS is rather weak and hence showers/storms will be rather lacking in organisation, but slow storm motion will likely produce 10-15mm rain accumulations in just 1-2 hours, with elements of shower training also - and hence there is a risk of some local surface water flooding issues.

It is hard to ascertain any particular areas where showers/storms are most likely to occur, hence the broad SLGT, although most NWP are in agreement for north Cornwall/Devon eastwards along M4 corridor to Thames Estuary as being on area of focus, along with S + E Wales into the W Midlands perhaps. Coverage (albeit still fairly well-scattered) may continue to expand in the SLGT well into the evening hours, before eventual decay takes over later in the evening due to nocturnal cooling. A few funnel clouds or a weak tornado are possible close to convergence zones.

Some question marks remain over how quick frontal rain clears East Anglia/Lincolnshire during the morning, which may inhibit convection here until quite late in the day. There is also a suggestion that frontal rain may turn more convective in nature across parts of northern England perhaps. 

http://www.convectiveweather.co.uk/