Mesoscale Discussion
Valid: Fri 28 Aug 2020 16:00 to Fri 28 Aug 2020 18:00 UTC
Issued: Fri 28 Aug 2020 16:23
Forecaster: PISTOTNIK

... NE Italy ...

A long-lived, right-moving supercell has tracked along the Alpine rim through the provinces of Bergamo, Brescia and Verona in the past couple of hours. It has a history of producing 2-4 cm sized hail, severe straight-line winds and localized flooding. Despite some periods of struggling against the capping inversion, it experienced repeated cycles of intensification, in which it also looked very severe from the radar and satellite üerspective (distinct V-shape and overshooting tops with temperatures down to -70C, corresponding to cloud top heights of 13-14 km).
Monitoring latest station data, the storm - meanwhile in the province of Vicenza - is about to enter the sea breeze regime with slightly lower temperatures (~28C compared to ~30C before) but even higher dewpoints (~23C compared to ~18C before). The next 1-2 hours will show if this storm's updraft is robust enough to overcome the strengthening cap. If it does, it can benefit from even higher CAPE values (2000-3000 J/kg, when modifying the 12 UTC Rivolto soundings with the latest station measurements). Together with enhanced 0-1 km shear in the sea breeze and particularly low cloud bases, this would point to a significantly enhanced tornado threat next to a continued risk of large hail and severe downbursts.

There are other signs of convective initiation along the Alpine rim further northeast towards Friuli. This convection might still be elevated at the time of writing, but should be closely monitored for signs of becoming surface-based. In that case, they can quickly produce all kinds of severe weather as well.