A negatively tilted trough will introduce a plume of warmer air as a warm front advances northeastward, while a cold front decays as it moves eastward. This complex frontal system will create a significant amount of uncertainty. According to the latest CAM model, there is a chance for elevated thunderstorms to develop across parts of the West Midlands and Northwest England during the late afternoon and early evening, as warm air from the warm front interacts with the outflow boundary of the cold front. Deep Layer Shear (DLS) and Low-Level Shear (LLS) of 20-30 knots will be just sufficient for these elevated thunderstorms to be long-lasting. Lightning activity could be quite frequent due to low saturation ahead of the cold front. Relatively high PWAT (35-40 mm) will increase the risk of localized flash flooding.
It is important to emphasize that destabilizing plume events are inherently uncertain due to their complex nature. Consequently, an element of unpredictability always exists in these situations. There is a risk that one or two elevated (super)cells could move northeastward into Kent and parts of East Anglia early Saturday night, as warm air interacts with the low pressure. High PWAT (40 mm) may cause localized flash flooding, particularly in parts of southeast England. The Deep Layer Shear (DLS) will be sufficient to sustain the cell across Southeast England; however, the lack of DLS in East Anglia is likely to weaken the cell. There is significant uncertainty surrounding this event, especially regarding the position of the cold front, which will influence the positions of the cells.
You can download the kml file of the convective outlook here:
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