Valid: Wed 14 Jun 2017 18:00 to Wed 14 Jun 2017 22:00 UTC
Issued: Wed 14 Jun 2017 18:42
... N Italy ...
Two MCSs, possibly with embedded supercells, have been active for several hours over the Piedmonte and Lombardia regions. An axis of pronounced convergence runs from their present position SE-ward, created by the outflow of the severe Friulian storm system from the afternoon (which is still active offshore!) and by Adriatic sea breezes. It is therefore expected that the storm systems will abandon their E-ward motion and will propagate to the SE into Veneto and Emilia Romagna, respectively. Additional initiation ahead of the MCSs may occur anytime (e.g., recently over the Appennin mountains west of Bologna).
In an environment of moderate to high CAPE (1000-2000 J/kg) and strong 0-6 km shear (15-20 m/s), these storms pose a high risk of large hail and severe wind gusts. Flash floods have to expected especially in case of backbuilding.
A tornado is not ruled out along the sea breeze front where low-level wind shear is enhanced by 5 m/s easterly surface winds and vorticity may be concentrated.