Convective Outlook: Mon 23 Sep 2019
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Mon 23 Sep 2019 - 05:59 UTC Tue 24 Sep 2019

ISSUED 05:43 UTC Mon 23 Sep 2019

ISSUED BY: Dan

A cold front will clear northern Scotland on Monday, but the backbent occlusion may provide the focus for a few heavy showers across Scotland during the afternoon. Otherwise, the main interest for lightning activity will be associated with the next frontal system arriving from the Atlantic - and more specifically the post-frontal environment, where a warm, moist low-level airmass (dewpoints 14-17C) will spread across Ireland and central and southern Britain during Monday night beneath an increasingly negatively-tilted upper trough and left entrance of a mid-level jet.


The exact detail of the forecast evolution is a little complex, but with 400 - 800 J/kg CAPE over the Celtic Sea / English Channel and strong forcing aloft clusters of showers, some with sporadic lightning, will likely develop over open seas and feed inland on the southwesterly steering winds, perhaps merging into more organised areas of intense convective rainfall. This is a fairly typical autumn-type setup, and as such it is possible an isolated tornado may occur - more especially close to the south coast. Localised flooding, gusty winds and hail 1.0-1.5cm in diameter will be additional hazards.