VALID 06:00 UTC Wed 11 May 2022 - 05:59 UTC Thu 12 May 2022

ISSUED 06:11 UTC Wed 11 May 2022

ISSUED BY: Dan

Longwave upper trough swings eastwards across the British Isles on Wednesday, with cooling aloft aiding instability and a few hundred J/kg CAPE in places. Meanwhile, a susbtantial dry intrusion will engage with a waving front across England and Wales, and has the potential to induce the development of a mesolow (similar to 31 Oct 2021, but less intense). Model guidance varies as to whether this occurs or if the front remains flatter/more linear in nature, but should a mesolow develop then there will be an enhanced risk of short-lived small tornadoes close to the intense shallow convection on its interior western flank where low-level shear/helicity is maximised. This seems most likely to occur in a WSW-ENE corridor from Pembrokeshire across the Midlands to Lincs/East Anglia. The relatively shallow depth of convection, weak CAPE and moist profiles will restrict the risk of lightning. If a flatter frontal wave evolves then the more likely scenario is shallow line convection (SMZ) with a brief spell of heavy rain and gusty winds.