VALID 06:00 UTC Wed 06 Apr 2022 - 05:59 UTC Thu 07 Apr 2022

ISSUED 08:27 UTC Wed 06 Apr 2022

ISSUED BY: Dan

A broad west-southwesterly flow aloft covers the UK/Ireland on Wednesday, with a sharpening shortwave trough embedded within migrating eastwards during daylight hours. A weak surface cold front will clear SE England first thing in the morning, but with likely fairly extensive cloud cover for a few hours that will tend to limit surface heating. A more organised area of showery rain is expected to track eastwards from southern Ireland across England and Wales during the day, perhaps fragmenting with time into heavy showers, and in either case followed by numerous showers in its wake. By this stage some modest surface heating in conjunction with the passage of the cold pool/shortwave aloft will yield a few hundred J/kg CAPE. However, forecast profiles appear to be fairly moist with depth, and this coupled with skinny CAPE and relatively shallow convective depth suggests the overall risk of lightning is fairly low (but non-zero) in any one location. Convective cloud that can reach heights at/exceeding 12,000ft would in theory be able to utilise the stronger flow aloft, allowing some tilting of updrafts and hence some organisation/longevity of cells. The main threat will be gusty winds (generally 40-55mph), although if some stronger convection could develop then in theory an isolated tornado could not be ruled out given slight backing of low-level winds and reasonable low-level speed shear. A few lightning strikes may be possible - based on climatology perhaps the London area, and just offshore from the Yorkshire/Lincolnshire coast, but confidence is far too low to justify the introduction of a SLGT. The risk of somewhat organised shallow convection persists overnight, while a frontal wave runs across southern Britain with embedded line convection possible.