Storm Forecast
Valid: Tue 15 Nov 2016 06:00 to Wed 16 Nov 2016 06:00 UTC
Issued: Mon 14 Nov 2016 20:50
Forecaster: DAFIS

A level 1 was issued for S Italy, Malta, N Tunisia and N Algeria mainly for large hail, excessive rainfall and tornadoes.

SYNOPSIS / DISCUSSION

While cold mid-level air masses enter Mediterranean basin they become unstable and thunderstorms are expected mostly over Central Mediterranean basin. High pressure systems prevail in West and Central Europe and during Tuesday, a cold pool is expected to form above SW Mediterranean, a short-wave trough will be crossing East Balkans and Black Sea and another short-wave trough is approaching Scandinavia.

We have highlighted an area over Mediterranean Sea with a threat level 1 as NWP models predict DMC events and kinematics look suspicious for severe phenomena. First of all, steep mid-level lapse rates and moist PBL create some hundreds of CAPE available and the advection of positive vorticity provides lift to these air masses, especially during the first half of the day. Local convergence zones will additionally provide the necessary lift for the development of single cells that may become multicells since the DLS is expected to reach 20 m/s and SREH0-3 exceeds 10 m/s in South Sicily. Within these storms we forecast excessive rainfall due to slow motion of the cells (mostly in N Algeria), large hail (up to 2cm) due to steep lapse rates, high CAPE and strong DLS, as well as some waterspouts near the coasts because of the weak winds near the sea surface, the slow motion of the storms, the big difference in temperature between low/mid-level air masses and SST (sst - t850 14°C, sst - t500 42°C).