Convective Outlook Issued: Enhanced risk 27/08/2025 00:00 - 27/08/2025 23:59

A low-pressure pressure associated with ex-hurricane Erin will deepen in the next 24 hours and bring a band of heavy rain across most of the British Isles on Wednesday.

A leading warm front will gradually move westward into the western UK and Ireland during the early hours of Wednesday. Sufficient mid-level instability (CAPE of 500-700J/kg) with moderate deep-level shear (40-50 kn) across the Celtic Sea will allow thunderstorms to initiate along the active showers on the warm front. Frequent lightning is likely initially, with squally and torrential showers at first, but due to the increasingly saturated profile, the lightning density is likely to reduce over the morning as the warm front moves into the inland area and decays into an occluded front. Based on the curvature in the hodographs and low cloud baes, a brief tornado or two are possible, especially across Devon and Somerset.

Further showers behind the frontal systems will continue to affect many parts of the British Isles over the afternoon, with a potential for a few thunderstorms to develop across north-western parts of England at times.

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