Thunderstorms are likely to be ongoing across parts of north Wales / northwest England / southern Scotland (and eastern Irish Sea) at the beginning of this forecast period, which will continue to migrate NE-wards through Wednesday morning, posing a main threat of local flooding from prolonged torrential downpours, gusty winds but also a lesser-extent for large hail - these risks included for the issuance of a SVR. Thunderstorms are also likely to be present across northern Scotland, exiting to the Northern Isles at this time also.

Provided enough insolation can develop in the wake of any morning cloud cover, strong heating of a very warm, moist airmass should allow dewpoints to reach close to 20C in some parts of northern and eastern England, yielding some 1,000-1,500 Jkg-1 MLCAPE. This environment will be heavily capped initially, but a combination of strong surface heating, frontal forcing from an approaching cold front and falling heights aloft as the upper trough advances could all serve to weaken the cap, allowing explosive, but isolated/well-scattered thunderstorm development to occur during the afternoon and early evening hours across central/northern England initially, the risk transferring southwards and eastwards towards evening.

This is heavily-dependent on an overlap of these ingredients, and it is possible that the capping inversion may be too strong in many areas. Nevertheless, should deep convection develop, high CAPE and 20-30kts DLS will allow any thunderstorms to become a little better organised, posing a threat for large hail to 3.5cm in diameter, strong, gusty winds and very heavy rain - hence the inclusion of a SVR to highlight these risks.