Convective Outlook UPDATED: High risk 03/09/2025 00:00 - 03/09/2025 23:59

A shortwave disturbance will move eastward along a negatively tilted trough across the south of a deepening low-pressure system. A warm and moist sector behind the cold front will allow some high-shear low-cape environment to develop. Powerful low-level shear and moderate deep-level shear with curved hodographs along the warm sector suggest updrafts within thunderstorms are possible.

Widespread scattered showers, often accompanied by strong gusts, are expected to affect a large portion of England as well as south Wales during Wednesday daytime. A saturated profile with little diurnal heating will limit any thunderstorm risk from developing inland initially, but as the left exit of the jet stream moves eastward during the late morning act as a main forcing, scattered severe thunderstorms will starts to develop along both English Channel and Bristol Channel.

Strong kinematic environment, including strong shearing and skinny cape supports tornado and supercell development, perhaps most likely across the southeast. This means, any post frontal showers that remained discrete or semi discrete will have the potential to develop into low-topped supercells. With the skinny CAPE and 9km cloud top are forecasted for many parts of England, semi-frequent lightning are likely in places. Very low LCL (<1km) and strong hodograph signal suggests there is a good potential for tornado development, especially across parts of southeast England.

2 main area of thunderstorms development have been highlighted by the moderate risk. A high risk has been issued for a portion of southeast England to highlight the potenial of severe thunderstorms development, especially when discrete cells manage to development there. 55-65 mph gusts, heavy rain are likely, with the chance of a tornado or two as well as small hail are possible, although lightning activity may not be as frequent as previous high risk events.

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