VALID 06:00 UTC Mon 10 Apr 2023 - 05:59 UTC Tue 11 Apr 2023

ISSUED 06:24 UTC Mon 10 Apr 2023

ISSUED BY: Dan

A longwave upper trough over the Atlantic will extend eastwards across the British Isles on Monday, associated with a substantial cold pool aloft. On its southern flank a powerful 160kt westerly jet will sit over southern Britain for much of the day. A cold front, and associated band of frontal rain, will clear eastern Britain on Monday morning, leaving an unstable environment in its wake as cold air aloft overspreads relatively warm SSTs and diurnal heating inland. A pronounced shortwave trough over the Celtic Sea and southern Ireland at 06z, co-located beneath the left exit of the aforementioned jet streak, will quickly progress eastwards into Wales and England through the morning and early afternoon hours. This will be associated with an organised curl of showery rain, which may tend to fragment and intensify as it travels east inland across Britain and encompasses greater instability. As such, the threat for strong wind gusts (50-60mph) will increase with time and eastward extent. In its wake, somewhat more discrete convection/showers is expected, although even these may tend to grow upscale into clusters at times given the strongly-sheared environment. Strong gusts of wind are the main hazard with the most intense cells, albeit probably just below severe limits, although an isolated tornado may also be possible if any cells can acquire persistent low/mid-level rotation - but fairly unidirectional wind profiles will tend to limit the tornado threat.