Convective Outlook: Fri 08 Sep 2017
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Fri 08 Sep 2017 - 05:59 UTC Sat 09 Sep 2017

ISSUED 20:20 UTC Thu 07 Sep 2017

ISSUED BY: Dan

Large upper trough will dig south across the British Isles towards Biscay during Friday, accompanied by cool air aloft and steep mid-level lapse rates. Seasonally warm SSTs and diurnal heating inland will be sufficient to allow numerous showers to develop widely, some weakly-electrified with small hail - a low-end SLGT may need to be introduced to N and NE Scotland where potential is somewhat higher than many other parts. A few funnel clouds are possible.


The greatest focus, however, will be across southern Britain where a frontal wave will slide eastwards with an instant occlusion potentially developing on its northern flank. There is still some uncertainty as to the exact forecast evolution, but scope for increased forcing to coincide with peak diurnal heating to generate an area of showers and thunderstorms that then migrates eastwards during the afternoon and evening hours across the SLGT.
Some of this activity could become reasonably well-organised given some DLS, capable of producing some notably gusty winds and hail up to 1.5-2.0cm in places. This is highly dependant on how much cloud may be associated with the frontal wave, which may ultimately serve as an inhibitor to deep convection.