Storm & Convective Discussion 12z 21/7/14 ------>

[vladthemert]

missed the fun yesterday but  2 storms here.   Another is turns out there was few notches in some storms Tony Gilbert showed one here its a bit further down I cant post pics from here. 

 

http://www.ukweatherworld.co.uk/forum/index.php?/topic/104468-convective-outlook-sat-2nd-aug-2014/

 

 

 

Today Tony Gilbert has moderate risk over scotland.

 

Crikey bit strong breeze here.   15 mph winds with gusts of 31 mph getting average of 26mph.   Was this scheduled 

[Spikecollie]

We had a 90 minute thunderstorm here in Limousin this morning which started at about 0900. Daytime darkness, and the storm seemed very elevated and was very slow moving. The pre-storm clouds were amazing. Magic!

Edited August 3, 2014 by Spikecollie

[East_England_Stormchaser91]

TS Bertha could well pose a risk of producing a mother of all plumes should she head towards Iberia and Bay of Biscay. The ECM seems keen on this solution anyway.

Interesting model watching coming up this week I feel!

[Ross Andrew Hemphill]

Big showers to the south of me currently. Sky is threatening, just have to wait and see if it produces lightning or just very heavy rain.

 

 

Edit: First big rumble heard!!

Edited August 3, 2014 by Ross Andrew Hemphill

[Stormyking]

This next week is interesting me in terms of showers and possible storms in places, gotta good feeling it could well be an interesting one

[mountain shadow]

Boom in Belfast with sheet lightning and torrential rain

[Cookie]

Thunderstorm here on the isle of lewis been sat on the beach watching! 

[Stuart]

seen some Lighting but was about 10 miles northwest  from  us but it all gone now but next day is Wednesday  

[davehsug]

Big storm about to hit Malmo/Copenhagen. Been looking around for a decent webcam, but can't find anything. Anyone got any help?

[Paul Sherman]

Thunderstorm here on the isle of lewis been sat on the beach watching! 

 

Who has taken over your account Richard ?

 

Now I know YOU Would not be sat on the beach watching a thunderstorm! Lol

[Mapantz]

Strange few weeks ahead.. No definitive thundery outbreak but there's likely to be plenty of opportunities for showers with hail and thunder mixed in. Too early for details but it shouldn't be a ghost town- Fun synoptics from someone who is a weather all-rounder.

[Stormyking]

Got a good feeling that friday could see some thundery downpours behind the main band of rain, especially the further South you are

 

[BrickFielder]

 Possible occluded front crossing parts of the UK tomorrow afternoon. Environment is likely to be slightly unstable.

Not the most unstable environment or richest environment for thunderstorms on the face of it.

What does interest me is the wind flow environment.

Slight veering in the wind at the lowest level.

Marked veering of the wind between 850hpa and 500hpa, but also notice 925hpa winds are slightly stronger than at 850hpa.

Quite a strong wind aloft as well.

 

Since the winds speeds veer with height even though the winds are not that strong, which could give rise to some storm rotation. Moisture inflow into any storm would be from the south while storms will generally travel east with a touch of northwards. Stronger winds aloft should help lift and would tend to drag any anvils eastwards. If temperatures are high enough and the forcing actually materializes then it might be possible to get a weak supercell.

 

Models dont seem to agree at the moment and the forcing for any convection seems a little dubious, but there is some potential for a surprise tomorrow. I just cannot get a grip on what the forcing is exactly.

 

Certainly something to keep an eye on, although it may still come to nothing.

 

 

Note:

With storms moving due east and with surface winds moving from the south unstable, warm, moist air enters the storm on the south side. The storm moves east because the upper-air steering winds are pushing it in that direction. Therefore, when the tower of the storm goes up it gets tilted downwind to the east of the updraft, and rain falls ahead of the storm.Here rain falls ahead of the updraft. So when you have warm  air flowing toward the southern side of an eastbound storm, that air can enter the storm unobstructed by precipitation, thus allowing for warm, buoyant air to drive the updraft. A strong unobstructed updraft is key to lifting low level horizontal vorticity. (Think very slight weak tornado risk tomorrow - still questions marks about the available tilt in towers tomorrow - if any form at all )

[Paul]

We're just tuning an updated NMM model behind the scenes currently and thought I'd share a few shots from it to tie in with BF's very informative post above. As he said there's quite a lot of uncertainty between models currently & the new (still experimental) NMM gives a slightly different slant.

Edited August 4, 2014 by Paul

[Lauren]

So what does that mean, Paul?

[Paul]

Comparing to BF's post which uses the NMM6 it's  firing the convection in slightly different places, but just subtle differences at this point which highlights the difficulty in nailing down any potential activity tomorrow.

[Stormyking]

Few showere around at the moment, had a fairly heavy one come through earlier, skies looks quite strange

[Frank Trough]

Apologies if this has been mentioned elsewhere but I just stumbled on this photo taken yesterday at about 8:30am out in the channel south of the Isle of wight:

 

http://iowbirds.awardspace.com/Pictures/Waterspout919aCulver040814.jpg

[BrickFielder]

Today 

 

Slight change in the models from Yesterday to today.

 

  Fairly high cloud tops sugegsted yeterday , but today.

 

This makes the difference between a storm and a heavy shower. It also means convection does not really tap into the faster winds aloft. What we should get is some photogenic heavy showers. Winds are light but turning through the convective height. This will mean that towers will tend to lean eastwards giving good updraft and downdraft seperation. Low level winds will still feed in from the south, but cloud cover ahead of these showers may limit convection along with temperatures struggling to get into the 20s.

 

 

Tomorrow

 

More chances tomorrow with at current steeper lapse rates forecast.

 

East Anglia maybe looking best at the moment.

 

[Evening thunder]

Some torrential showers to my north producing nice CB's, some turrets seem to go up higher than the rest of the CB with pelius on top, before being blown downwind. 

[Weatherbimbo]

Absolutely chucked it down here about an hour ago. Local roads flooded. Bright sunshine now with huge Clouds building. Exciting.

[TonyH]

Sferics from heavy showers over Powys near Welshpool

[Supacell]

Some isolated, rather weak storms scattered around the West Midlands currently.

[Joey.G]

Some decent storms over NI at the mo, slowly coming this way. Very rare I think for storms over there to make a crossing over to here but think there maybe is a chance tonight. The current rain over here has a v high cloud base and its v warm and muggy for here. Maybe someone could give a bit more insight into whats going on and either boost or dash my hopes?!

[Dazza]

Some decent storms over NI at the mo, slowly coming this way. Very rare I think for storms over there to make a crossing over to here but think there maybe is a chance tonight. The current rain over here has a v high cloud base and its v warm and muggy for here. Maybe someone could give a bit more insight into whats going on and either boost or dash my hopes?!

You're right there Joey, fantastic storm passed over us for about an hour, plenty of Lightning and cloud rotation too, passed NE though, not sure if you are inline or not. It really built out of nothing and intensified, I got very excited about the cloud rotation but it moved off on its merry way taking the rotation with it into the distance. Some pics: