tekst:
Northern France, British Isles
Underneath the cyclonically-sheared flank of the mid-level jet streak, strong QG forcing is forecast to spread into northern France in the afternoon and evening hours. A low-level convergence line is expected to spread eastward over western France in the afternoon, leading to slightly backing surface winds over northern France, where south-westerly to southerly winds may evolve. With low-level mixing ratios of 8 g/kg and some diurnal heating, the neutral to slightly unstable air mass is expected to become increasingly unstable with low-level CAPE in the order of some 100s J/kg.
Thunderstorms are forecast along and ahead of the convergence line that will spread eastward in the evening hours. Given increasing south-westerly winds at 850 hPa, low-level veering profiles will become favourably supportive for storm rotation (0-1 km SRH 120-160 m²/s²). Mesocyclones are forecast to develop, capable of producing tornadoes. Isolated large hail and severe wind gusts are not ruled out.
Farther north, the severe potential decreases over the British Isles. Although instability and vertical wind shear do not seem to be supportive, a tornado is not completely ruled out.
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