An area of unseasonably deep low pressure will move into the British Isles from Northern Atlantic, where a warm theta-e southwesterly plume will be introduced by the active warm front. This means heavy showers with blustery winds will move North into most parts of England and Ireland. The remainder of the sporadic elevated thunderstorms might decay in the low-risk across northern England and northern parts of East Anglia in the early morning.
Starting from the early afternoon, clouds across southern England and parts of England will start to break as the active warm front move northward and decay. This means surface heating will starts and erode the shallow mid-level CAP, therefore CAPE will rapidly intensify in the early afternoon, allowing convectivity to develop along the northern edge of an occluded front. MUCAPE of 600-100 J/kg will allow sporadic thunderstorms to develop quickly, where this is enhanced by the strong shear from the south, as well as the convergence zones in the Midlands. This means a narrow corridor with a favourable environment will allow thunderstorms to develop. These thunderstorms will be rather sporadic at first but might intensify into an area of organised thunderstorms when they move east into parts of North Wessex Downs due to the convergence zone. Hail showers are possible in places due to moderation shearing.
When the main cluster of thunderstorms moves east, further moisture will be supplied from the Bristol Channel, which allows more sporadic thunderstorms to develop from Somerset/ Glouceshire areas. This will bring a risk of training effect as multiple areas of showers hit similar areas, causing localised disruption such as flooding, especially across the M4 motorway.
In the meantime, blustery showers will develop along the south coasts, bringing some gusty wind (50-60mph) in places.
Thunderstorms will start to weaken in the early night due to the reduction of surface heating.
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