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Storms and Convective discussion- 7th August onwards


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The latest YouTube Met office update is a bit of a shocker not much about at all except Eastern Scotland, totally different from last nights update for today especially for us in North East England 

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A beautiful altocumulus castellanus sunrise this morning. 

Oo she's a beauty 

My first attempt at storm shots 🤷‍♂️ (Please don't judge 🤣) The cells are impressive tonight! 

Posted Images

1 minute ago, Tom Jarvis said:

East Grinstead cell has collapsed now 

Might find it tries and tries before punching through. Based on @staplehurst forecast we are pretty much at the point where the cap can go 

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I see we're beginning to get cumulus bubbling here. Been another scorcher, 32c so far. So perhaps we'll see occasional storms cropping up now?  Something fired up east of here so watching that carefully...  and it is tracking NNE not NNW.

Edited by StormLoser
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1 minute ago, tomp456 said:

Looking forward to the all too common NOTHING along the west sussex coast later on. 

 

 

Well you were never really forecast anything today so I don't see the issue?

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5 minutes ago, Boro Snow said:

The latest YouTube Met office update is a bit of a shocker not much about at all except Eastern Scotland, totally different from last nights update for today especially for us in North East England 

Aye😂 If I speak I am in trouble. 

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10 minutes ago, UKSupercell said:

A lot of scattered cumulus here in S Bucks in fact one cell growing quite well to my south. CAPE levels here on Metcheck around 1,000 mark hitting towards 1,600 around 7pm. I was expecting late explosive development again like 7pmish yesterday. 

Think that's the cell I can see directly east.  It'll be other side of the river (of course)  possibly Henley direction?

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Latest AROME 12z almost spot on at the moment and targets an area between Birmingham-Northampton-Oxford around 10pm.

Edited by Ben Sainsbury
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My area has actually got maybe 1.5 degrees hotter today than it was meant too, were being forecast 29-30 its now 31.3. Good news.

Considering it was still 23c at 1 this afternoon, not bad going.

Edited by Calayte
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3 minutes ago, Ben Sainsbury said:

Latest AROME 12z almost spot on at the moment and targets an area between Birmingham-Northampton-Oxford around 10pm.

It can be only be spot when it happens and judged after the event.

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Given some reduction in dewpoints around the London area, modifying the 12z Herstmonceux ascent suggests a temperature of 33C would be required (in combination with lift from low-level convergence) to ultimately push through the EML and generate deep convection. Sounding yields just shy of 1,800 J/kg.CAPE. Given the large temperature-dewpoint spread, cloud bases are likely to be quite high (6,000ft or so).

Shear is very weak (10 kts) and in the absence of any larger scale forcing aloft any storm that does develop, while doing so explosively, will ultimately be of pulse-variety and likely rain in on itself and so have a short life duration (1-2 hours). Likely to be some very gusty downburst winds (hazards for Heathrow etc), and this outflow could help spawn daughter cells. Steering flow aloft appears to be southwesterly, so in theory storms will drift very slowly (15mph) to the NE, if daughter cells form southwest of the parent cell then this will give an element of training and heighten the risk of flooding. Slow storm motion and high PWAT brings the risk of point flash flooding. Magnitude of CAPE and steep mid-level lapse rates could produce some large hail. 

HERST.JPG

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3 minutes ago, staplehurst said:

Given some reduction in dewpoints around the London area, modifying the 12z Herstmonceux ascent suggests a temperature of 33C would be required (in combination with lift from low-level convergence) to ultimately push through the EML and generate deep convection. Sounding yields just shy of 1,800 J/kg.CAPE. Given the large temperature-dewpoint spread, cloud bases are likely to be quite high (6,000ft or so).

Shear is very weak (10 kts) and in the absence of any larger scale forcing aloft any storm that does develop, while doing so explosively, will ultimately be of pulse-variety and likely rain in on itself and so have a short life duration (1-2 hours). Likely to be some very gusty downburst winds (hazards for Heathrow etc), and this outflow could help spawn daughter cells. Steering flow aloft appears to be southwesterly, so in theory storms will drift very slowly (15mph) to the NE, if daughter cells form southwest of the parent cell then this will give an element of training and heighten the risk of flooding. Slow storm motion and high PWAT brings the risk of point flash flooding. Magnitude of CAPE and steep mid-level lapse rates could produce some large hail. 

HERST.JPG

@staplehurst whats the thoughts on tomorrow and tomorrow night mate please?

Edited by viking_smb
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1 minute ago, The PIT said:

It can be only be spot when it happens and judged after the event.

A lot of hi-res models start the run incorrectly like the latest UKV run for example, AROME 12z at 4pm is in-line with the current situation and therefore shows real potential.

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7 minutes ago, jake44 said:

image.thumb.png.d23359351fafa47e37275a53abe1835a.pngboy oh boy thats getting very strong now

Depends on what it is, if it develops an mcs, they have their own micro climate, which could keep it going. Unfortunately I'm not sure that it is one, in which case they will erode on our cap. 

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