Storm Forecast Valid: Mon 16 Mar 2015 06:00 to Tue 17 Mar 2015 06:00 UTC Issued: Mon 16 Mar 2015 04:18 Forecaster: VAN DER VELDE
A level 1 was issued for Sardinia and Sicily mainly for chances of isolated large hail, tornadoes and excessive convective precipitation.
SYNOPSIS / DISCUSSION
An upper trough is located over western Europe, with relatively shallow storms with isolated thunder in th slightly unstable cold airmass over France and the western Mediterranean. The weak surface low shifts from northeastern Spain to Corsica/Sardinia with a plume of warm unstable air advecting from Tunesia and the Thyrrenian Sea northwestward into an occlusion over the northern Mediterranean basin. MUCAPE of 100-400 J/kg is concentrated mainly along a cold front between Tunesia and Sardinia. Low level convergence is focused into a line which should trigger storms which move only slowly (<5 m/s) while moisture transport is lifted over the east coast of Sardinia. It combines with moderate vertical wind shear (15 m/s and 150-250 m²/s² 0-3 km SREH). Some supercells may form in such environment, whose main threat is large hail and local excessive precipitation. The low levels are very humid and have 0-1 km shear around 10 m/s, which enhance precipitation and tornado chances. A new low will arrive to Portugal early Tuesday. Its cold front is backed by a healthy PV lobe which may trigger a linear convective system, but CAPE is rather low and barely reaches the coast before 06Z.