Storm Forecast
Valid: Wed 12 Dec 2007 06:00 to Thu 13 Dec 2007 06:00 UTC
Issued: Tue 11 Dec 2007 20:40
Forecaster: GATZEN

SYNOPSIS/DISCUSSION

A ridge amplifies over western Europe, while a trough stretches into central and east Mediterranean. While cold air mass starts to spread into west Mediterranean, relatively warm and most low-level air mass is present
south and east of the cold front, with a slight temperature increase to the east. The warm air mass is characterized by steep lapse rates and rather rich low-level moisture, indicated by inverted-v-profiles. Latest ascends show CAPE up to 100 J/kg at the north-African coast.

On Wednesday, upper trough spreads eastward. A strong mid-level jet curves around the trough providing QG forcing over east Mediterranean. Given unstable air mass and rather weak CIN, showers and thunderstorms will likely develop over a broad region from central Mediterranean to southern Turkey, and southern Aegean. Vertical wind shear will rather strong reaching more than 15 m/s in the lowest 3 km in the range of the 700 hPa jet pointing towards south-west Turkey. Given also favourably veering profiles, thunderstorms will likely organize into bowing lines and mesocyclones. These will be capable of producing tornadoes from Crete to southern Turkey given strong low-level helicity and low-level buoyancy in the range of very humid low-level air mass. Given strong winds at low-levels, even strong tornadoes are not ruled out. Sever wind gusts and large hail may be also possible.

Over south Mediterranean, strong vertical wind shear in the range of the jet will be present, and thunderstorms that form may produce severe wind gusts.

Over central/north Mediterranean, weak vertical wind shear and rather strong low-level buoyancy are present, and a few waterspouts may form. Convective activity is expected to weaken during the period as the trough moves eastward and cold air advection sets in over west Mediterranean.