Convective Outlook: Fri 12 Mar 2021

LOW SLGT MDT HIGH SVR

What do these risk levels mean?

Convective Outlook

VALID 06:00 UTC Fri 12 Mar 2021 - 05:59 UTC Sat 13 Mar 2021

ISSUED 07:36 UTC Fri 12 Mar 2021

ISSUED BY: Dan

A broad westerly flow covers the British Isles on Friday, with cold air aloft generating steep mid-level lapse rates and a few hundred J/kg CAPE in response to SSTs and diurnal heating inland. A shortwave trough will clear eastern Britain by late morning, with a slight lull in convection likely for a time across central and southern Britain as slight ridging migrates from west to east through the day. A sharpening upper trough will swing eastwards through Friday evening and night, with a mixture of dynamic (frontal) and convective precipitation developing more widely during the overnight period in particular. Any of this activity through Friday daytime and overnight could produce a few sporadic lightning strikes, especially in western areas, but the risk in any one location is considered around 10-15% and therefore too low to warrant the introduction of a SLGT. The strongly sheared environment, especially across central/southern areas, will enable cells to produce squally winds and hail at times. The cold front tracking eastwards on Friday night could produce line segments across parts of Wales, SW / CS / SE England and perhaps the Midlands, and may be the focus for some squally winds at times (22-23z onwards).