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Storms and Convective discussion - 10th April 2020 onwards


Supacell

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Posted
  • Location: Bristol
  • Weather Preferences: Thunderstorms and Snowstorms
  • Location: Bristol
1 minute ago, Flash bang flash bang etc said:

GFS is actually showing storm potential for tomorrow afternoon. By tomorrow I mean today... Wednesday!

NMM actually supportive of this, some decent instability around actually.

NMM.thumb.png.7d3d6c4961d28a083c206deb588ebe65.png

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Posted
  • Location: Barton on Sea, Hampshire
  • Weather Preferences: Snowy winter, warm/hot summer with the odd storm thrown in
  • Location: Barton on Sea, Hampshire

Hints of something on UKV too for tomorrow afternoon

image.thumb.png.62ee20c44be861b718bb5ce6f3ff82db.png

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Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.

Tomorrow evening will hopefully give a better cross model agreement on the unfolding of this perplexed storm potential. Then it will be straight to the radar. 

Remember, we may see something elevated crop up out of the blue towards the SW during the night. It’s happened before!

Things do not by any means always go as per the precipitation predictions. 

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

Yep - convergence zones setting up in parts of East Anglia in the afternoon, combined with high Theta-E and some modest CAPE, certainly a small potential for a storm or two to develop.

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Posted
  • Location: Bedfordshire
  • Weather Preferences: Thunderstorms, plumes, snow, severe weather
  • Location: Bedfordshire

BBC Graphics. Mmmmm!!

0.png

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Posted
  • Location: Norwich, Norfolk, East Anglia
  • Weather Preferences: Sunny, stormy and I don't dislike rain only cold
  • Location: Norwich, Norfolk, East Anglia
41 minutes ago, Ben Sainsbury said:

EURO4 18z indicative of a marginally severe surface based thunderstorm across Norfolk Thursday mid-afternoon.

I'm not totally surprised about this, although I hadn't really focused on it, if anything develops nearby, I'll head out

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Posted
  • Location: Barton on Sea, Hampshire
  • Weather Preferences: Snowy winter, warm/hot summer with the odd storm thrown in
  • Location: Barton on Sea, Hampshire

Updated UKV

temp.gif

Edited by matt111
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Posted
  • Location: Bristol
  • Weather Preferences: Thunderstorms and Snowstorms
  • Location: Bristol

Sorry to put a downer on things but I'm quite disappointed by this mornings output. Intensity and distribution of storms seems to really have shunted east and definitely has been toned down overnight. I was all for chasing tomorrow but I don't think I will anymore unless CW issue a MDT. Hopefully we see improvements on today's runs.

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Posted
  • Location: Bexley (home), C London (work)
  • Weather Preferences: Thunderstorms
  • Location: Bexley (home), C London (work)
12 minutes ago, Ben Sainsbury said:

Sorry to put a downer on things but I'm quite disappointed by this mornings output. Intensity and distribution of storms seems to really have shunted east and definitely has been toned down overnight. I was all for chasing tomorrow but I don't think I will anymore unless CW issue a MDT. Hopefully we see improvements on today's runs.

Agreed, WRF-NMM 0z run rowing right back on CAPE extent and storm development, indicating decent MUCAPE moving in across the far SE around 05:00 then hanging around much of the day - seems to think some spotty storms in a line from say Brighton to Lowestoft through the morning then further storms across chiefly Kent/Essex during the afternoon. 

Euro4 still plumping for convective developments in similar areas to yesterday (per CW map) but more concentrated across EA.

The model the BBC use in my experience does tend to over-do precipitation, but it will be interesting to see which model 24 hours out has the best handle on this evolution.

With some MUCAPE still anticipated and elevated popcorn outbreaks indicated by the modelling, that’s good enough for me. Although the fact it’s limited increasingly to the SE suggests a chance the really unstable air may not make it here at all which would be the nail in the coffin for this ‘event’.

Edited by Harry
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Posted
  • Location: NW London
  • Weather Preferences: Convective Weather and Snow
  • Location: NW London

After waking up and reading the latest model thread, I was feeling quite sad about Thursday's potential until I had a quick look at the UKV model. There seems to be some more of a trend from the latest models of less elevated convection, allowing the sun to clear and some CAPE to build in the south-east corner, along with some surface based T-Storms. Although I would miss out on this scenario, it could be something that is worth taking note of.

Edited by Thunder and Lightning
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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

East Anglia spot to be tomorrow morning according to 00z EC ...

overview_20200520_00_033.thumb.jpg.dbfd6cacc007ccb81a2726b876a36317.jpg

... though given time of day, imagine the storms developing will be elevated. The upper trough passage, that's causing the large scale ascent of the warm humid plume of air around 850mb, a little to early to initiate surface-based convection during peak heating in the afternoon. As always, the models often struggle to simulate exactly where storms will develop, so by no means any model is correct with spatial distribution of breaking out storms. Suspect there maybe initian over the SE earlier before storms move NE across EA in the afternoon.

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Posted
  • Location: Plymouth, Devon
  • Weather Preferences: Thunderstorms, hail, tornado, cloud
  • Location: Plymouth, Devon

I personally think this has all been hyped up over nothing. We will see but as time goes on it’s looking lesser.

 

its like mummy telling you if you have been good you can have an ice lolly at the end of the day and you spend all day being good deciding what flavour you want to finally getting there and realising the lolly you want isn’t there and if fact the ice cream van isn’t around.

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Posted
  • Location: Woodchurch, Kent.
  • Weather Preferences: Storm, drizzle
  • Location: Woodchurch, Kent.

met Office not looking good apart from late afternoon

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Posted
  • Location: Bexley (home), C London (work)
  • Weather Preferences: Thunderstorms
  • Location: Bexley (home), C London (work)
6 minutes ago, Xanderp009 said:

met Office not looking good apart from late afternoon

Indeed, it is not expecting the trough (which seems to be highlighted by the passage of rain across the SW then evolution of storms across the continent around lunchtime) to generate storms at all. Afternoon storms appear to be possibly linked to a CZ judging by the axis - and CZs are notoriously fickle beasts 

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Posted
  • Location: Thorley, west Isle of Wight
  • Weather Preferences: Spanish plumes & stormy winters. Facebook @ Lance's Lightning Shots
  • Location: Thorley, west Isle of Wight

Wow, what a downer from the models this morning! Maybe I won't be chasing at all tomorrow 

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Posted
  • Location: NW London
  • Weather Preferences: Convective Weather and Snow
  • Location: NW London
1 minute ago, Mapantz said:

It's a complex situation, but I wouldn't write it off yet. 

The models changed quickly so hopefully they can go back just as fast 

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Worth noting these storms will be mostly elevated, so "rainfall" on the graphics isn't really representative of where storms will be. UKV is also particularly bad when it comes to predicting elevated thunderstorms, it's a known weakness within the model.

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Posted
  • Location: Aviemore
  • Location: Aviemore
9 minutes ago, Met4Cast said:

Worth noting these storms will be mostly elevated, so "rainfall" on the graphics isn't really representative of where storms will be. UKV is also particularly bad when it comes to predicting elevated thunderstorms, it's a known weakness within the model.

Can't say I've heard of that issue - where did you get the info from?

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Posted
  • Location: Bexley (home), C London (work)
  • Weather Preferences: Thunderstorms
  • Location: Bexley (home), C London (work)

Dan’s latest forecast for more especially overnight 

Day 1 Convective Outlook

VALID 06:00 UTC Wed 20 May 2020 - 05:59 UTC Thu 21 May 2020 

ISSUED 06:50 UTC Wed 20 May 2020

ISSUED BY: Dan

Upper ridging largely dominates across the British Isles through Wednesday, and despite some SBCAPE developing over eastern England in response to diurnal heating, profiles are heavily subsided and capped - hence at best some shallow convective cloud is likely. 

Late in the day, showery bursts of rain will spread into W / SW Ireland associated with a cold front. This will continue to track east across Ireland and W Scotland during the evening and night hours, for a time being engaged by a sharpening shortwave approaching from the Atlantic. This may, for a time, increase the potential for some embedded elevated convection, however as the shortwave overruns the cold front the focus will shift to a new corridor of elevated convection that is likely to develop in the vicinity of the Irish Sea / W Britain during the early hours of Thursday - ahead of the cold front. Given rather weak instability, the risk of lightning is considered relatively low but a few isolated lightning strikes may be possible, hence the inclusion of a LOW threat level.

Elsewhere, as the shortwave continues to advance eastwards, by the end of the night it may begin to engage with a plume of high Theta-W advecting from France into Cen S / SE England. Gradual cooling and moistening of the mid-levels, combined with forced ascent, may result in scattered elevated showers develop in the vicinity of the English Channel / S Midlands / S + SE England. As such, a few sporadic lightning strikes may occur late in the night, but the risk is greater beyond this forecast period (i.e. after 06z Thursday). The extent to how much moistening occurs at the 700-850mb level will be crucial in determining how much elevated convection can occur, with disparities between model guidance at present. Nonetheless, a (low confidence) SLGT has been issued to cater for any thunderstorms that develop late in the night, since these could produce fairly frequent lightning given the rapidly increasing instability as the upper trough approaches - initially with very little precipitation reaching the ground until the boundary layer gradually moistens. 

 

E1449760-580B-44CE-8956-7D5253788012.png

Edited by Harry
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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent
5 minutes ago, Paul said:

Can't say I've heard of that issue - where did you get the info from?

A few of the pros over on Twitter when the UKV was first introduced onto Extra. I asked about it's known weaknesses/biases. 

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