...Northern France, Benelux, southern Great Britain ...
Strong southwesterly flow present over western Europe ... and embedded short-wave trough/vort-max will cross northern France/Benelux and southern Great Britain during the next hours. Downstream of this feature ... plume of warm airmass is advected northward ... with a Theta-E axis reaching from central France to southeastern Great Britain in the evening. Large CAPE is not expected as steep mid-level lapse rates will remain over southern and central France, where more than 2000 J/kg may be possible. However ... strong UVM due to strong WAA is forecast ... and thunderstorm initiation is expected in the range of a weak surface low over southern central England, where easterly surface winds are forecast ... and upslope flow/low-level convergence is likely. Thunderstorms that form should encounter boundary layer airmass as low-level air should be rather moist and warm with temperatures in the range of 24°C, allowing for CAPE up to several hundred J/kg. Developing thunderstorms may organize due to rather strong (20 m/s+) deep layer wind shear and increasing low-level wind shear due to forecast easterly surface winds over southern Great Britain, northern France and Benelux. Supercells are possible capable of producing large hail and damaging wind gusts. There is also an enhanced chance of tornadoes. Thunderstorms should merge into a MCS that is expected to reach southern Great Britain and Benelux. Heavy precipitation, severe wind gusts and isolated large hail are expected. Tornadoes are not ruled out. For the southeastern part of the SLGT RISK area see previous outlook.
