Large CAPE forecast

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Len Wood

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Jul 18, 2016, 11:44:37 AM7/18/16
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This GFS output for Tues 1800 UTC  looks a bit fruity for thunderstorms.
But where exactly in the UK?
Looks worse up north.


Richard Dixon

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Jul 18, 2016, 12:08:57 PM7/18/16
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Would be interesting to know how rare 2000+ J/kg values occur in the UK...Once every two years or so?

Based on this CAPE climatology paper:


...it seems that once every 2-3 years seems reasonable. Maximum CAPE here for 9 years here:


Richard

Len Wood

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Jul 19, 2016, 4:54:47 AM7/19/16
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Even more purple (>2000) forecast for 1800 today


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xmetman

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Jul 19, 2016, 5:09:24 AM7/19/16
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Len

CAPE is just potential, but for the bulk of England it doesn't look like that potential will be put to any use!

Bruce.

Richard Dixon

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Jul 19, 2016, 5:18:40 AM7/19/16
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Is that a maximum of >3000 J/kg I can see over SW Manchester/Cheshire?

Richard

Len Wood

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Jul 19, 2016, 7:37:17 AM7/19/16
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Depends on vertical wind shear too Bruce
Might need to work out some bulk Richardson numbers.

If they are around 50 or below, thunderstorms are more likely.

I see there is some activity off Brest atm.

Len
Wembury.

Richard Dixon

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Jul 19, 2016, 7:41:25 AM7/19/16
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On Tuesday, 19 July 2016 12:37:17 UTC+1, Len Wood wrote:

I see there is some activity off Brest atm.

Interesting that none of the models appear to have got this area of showers...

Richard 

xmetman

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Jul 19, 2016, 7:47:03 AM7/19/16
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It needs a trigger, and you would think the switch to fresher air over the SW overnight would be enough to do it, but there seems to be no related weather with this airmass change in the south of the country.


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