Storm Forecast
Valid: Sun 21 Apr 2013 06:00 to Mon 22 Apr 2013 06:00 UTC
Issued: Sun 21 Apr 2013 00:21
Forecaster: VAN DER VELDE

A level 1 was issued for Italy and western Balkan mainly for isolated large hail.

SYNOPSIS / DISCUSSION

South of a Baltic surface high pressure area connected by a ridge to an Atlantic high, a mid/upper level low filled with relatively cold air in the mid levels moves from the western Mediterranean Sea to central Italy. Unstable stratification with weak capping is present over a large area, and large scale lifting provided by the advancing low favors widespread development of deep convection. Over the northern half of Italy, mainly, some moderate 15 m/s bulk 0-6 km shear vector magnitude will be present (10 m/s 0-3 km). This may induce some rotating updrafts with large hail production, although the mid level buoyancy is lacking. An isolated waterspout may occur near the center of the cold pool and convergence lines around Corsica and Sardinia, where vortices may spin up aided by lack of shear and slow cloud motion.