Convective Outlook: Wed 15 Jun 2016
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Wed 15 Jun 2016 - 05:59 UTC Thu 16 Jun 2016

ISSUED 12:03 UTC Wed 15 Jun 2016

ISSUED BY: Dan

UPDATE 12:03 UTC Minor adjustments made to extend SLGT and LOW slightly to the E in light of recent sea breeze developments in SE England/E Anglia, and to upgrade parts of Cumbria/SW Scotland. All other areas remain unchanged in-line with previous expectations

Very little change to the overall evolution - sharpening upper trough over the British Isles with cool(ing) mid-levels atop a moist surface airmass. Daytime heating will generate 400-700 Jkg-1 MLCAPE which, combined with forced ascent along areas of frictional convergence due to slack surface pressure and small areas of low pressure, will generate scattered showers and a few thunderstorms. Like Tuesday, unidirectional winds with height will lead to another day of pulse-type activity, with short-duration lightning activity per individual storm. Some marginally-better DLS will be present towards the SW peninsula which may allow cells to become a little more organised, but overall another day of messy convection is anticipated.

Broad risk of lightning, hence the large SLGT, although given activity will be mainly focussed along areas of convergence (which NWP suggests will be most pronounced from Norfolk through the Midlands to Wales and/or the West Country) there are likely to be quite a few locations that remain lightning- (if not, even shower-) free. The extent of lightning over the SW peninsula is questionable due to excessive cloud from old occlusion debris which may inhibit insolation to some extent.

Low cloud bases and areas of low-level convergence will promote the chance for a few funnel clouds or even a brief weak tornado. Hail up to 1.0cm in diameter is possible from any stronger cells, along with the ongoing threat for local flash flooding given prolonged downpours and/or elements of along-flow shower training.