Convective Outlook: Tue 06 Sep 2022
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Tue 06 Sep 2022 - 05:59 UTC Wed 07 Sep 2022

ISSUED 07:27 UTC Tue 06 Sep 2022

ISSUED BY: Dan

Upper low remains anchored to the west of Ireland, creating a widely unstable environment across the British Isles. A plume of steep mid-level lapse rates will cover N + NE England into S + SE Scotland, and so it is these regions that could yield some fairly active thunderstorms (potentially) with perhaps marginally-severe hail. Tentatively introduced a marginal MDT risk area where some CAM guidance suggests an active cluster may evolve through the afternoon and early evening, but it should be stressed confidence is much lower than compared with the MDT issued on Monday for example.

Elsewhere in the post-frontal environment with lower Theta-W than previous days, tall and skinny CAPE profiles, unstable also to SSTs, should aid numerous showers to develop, some heavy with sporadic lightning, but struggling to identify anything particularly well-organised given the lack of any strong forcing. Disparity between model guidance also lends to low confidence about the local detail during this forecast period, but given the widely unstable environment have reluctantly opted for a very broad-brush SLGT. There are hints a more organised cluster/area of showery rain may spread northeastwards during the afternoon and evening hours across central and southern Britain, but rather messy in appearance. A jet streak moving across northern France during the afternoon and evening will increase deep layer shear over central and southern Britain, and here 30-40kts could allow for cell organisation with the potential for a supercell if convection can remain fairly discrete.

Showers, and associated risk of lightning, will persist well into the night - especially in southern and western areas, but also potentially eastern Scotland and East Anglia / SE England.