Storm Forecast
Valid: Mon 07 Nov 2016 06:00 to Tue 08 Nov 2016 06:00 UTC
Issued: Mon 07 Nov 2016 05:59
Forecaster: VAN DER VELDE
A level 2 was issued for S Italy, Albania and Montenegro mainly for severe convective wind gusts, tornadoes, large hail and excessive convective rainfall.
A level 1 was issued for FYR Macedonia, N Greece, W Bulgaria, S Serbia mainly for chances of tornadoes and severe convective wind gusts.
A level 1 was issued for Balearic and western Mediterranean Sea mainly for waterspout type tornadoes.
SYNOPSIS
A major mid-level long-wave trough perturbs western Europe and the western Mediterranean region with cool, unstable weather, while advecting a warm air mass over southern Italy towards the southern Balkan, where it clashes with the advancing cool air mass over the Tyrrhenian Sea. A low pressure is predicted by GFS and local models to develop there under highly baroclinic conditions during the evening, rapidly taken by the southwesterly flow toward Albania. Upper winds in this region are 30 m/s from 850 hPa to 500 hPa and 50 m/s at 300 hPa.
DISCUSSION
...Tunesia, Malta, Sicilia, S Italy, Albania...
Models predict a CAPE of 700-1300 J/kg and a very sharp convergence along the cold front over the Tyrrhenian Sea. The main activity should develop during the evening and night. Strongly veering hodographs produce huge SREH values of 400-1000 m2/s2 which favors strong mesocyclones that can easily produce a (violent) tornado as well as large hail. Storm motion will be around 25 m/s with gusts in severe thunderstorms possibly over 30 m/s.Extremely severe phenomena may be reported, but the confidence in a high coverage is at the moment not enough to delineate a level 3. Excessive rain is expected mostly in N Albania and Montenegro where storms can persist longest. The threats continue to a lesser extent over a wider region of the southern Balkan.
...Catalonia to Balearic Islands...
NW-SE convergence lines will trigger convection which can, helped by steep surface to mid level lapse rates, weak low-level shear and slow storm motion, spin up vertical vorticity and produce waterspout type tornadoes.
