VALID 06:00 UTC Wed 10 May 2023 - 05:59 UTC Thu 11 May 2023

ISSUED 06:40 UTC Wed 10 May 2023

ISSUED BY: Dan

An upper trough will extend across the British Isles and across to Central Europe on Wednesday. A small cut-off upper low will loiter over the Low Countries, which casts some uncertainty as to the extent of cloud and showery rain over East Anglia/SE England and how slow/fast this pulls away to the east. Elsewhere, a typical showery day is anticipated with diurnal heating of a reasonably moist low-level airmass (Td 9-11C) yielding 200-500 J/kg MLCAPE (SBCAPE potentially up to 1,000 J/kg). Scattered showers are likely to develop by 11-12z as a rather subtle shortwave drifts eastwards across Wales into England, showers then maturing and intensifying as they migrate gradually eastwards such that by the time they reach eastern Britain a few sporadic lightning strikes will be possible in many places. One or two more active thunderstorms may be possible in the east Midlands, East Anglia and SE England by late afternoon/early evening. Sea breeze convergence developing in eastern England and along the south coast may enhance forced ascent to give an uptick in lightning activity as cells near the coast and drift offshore. Sub-severe hail and gusty winds will be possible with the most intense cells.