Storm Forecast
Valid: Thu 12 Mar 2009 06:00 to Fri 13 Mar 2009 06:00 UTC
Issued: Wed 11 Mar 2009 23:17
Forecaster: GATZEN

SYNOPSIS

A long-wave trough that extends well into the Mediterranean moves eastward during the period, while its axis crosses most of the Aegean. To the west, a subtropical high affects south-western Europe. A strong upper jet results from the British Isles to Germany and curves around the mentioned trough over central and east Mediterranean. At lower levels, rather cold air masses spread southward across central Mediterranean in the wake of a surface low over the Aegean. Another, quite intense low pressure system will move eastward north of the British Isles.

DISCUSSION

Aegean

Ahead of the approaching trough axis, a strong mid-level south-westerly jet crosses the Aegean. At lower levels, some QG forcing is likely ahead of the main cold front that moves southward over the Adriatic, and models indicate a deepening low that moves into the Aegean on Thursday. This will likely lead to southerly winds ahead of the low that will advect rather moist low-level air mass into the Aegean Sea. Low-level mixing ratio is expected to reach about 7 g/kg. Given rather steep mid-level lapse rates near the trough, models indicate the development of instability ahead of the cold front. Given quite strong forcing due to warm air advection, orographic lift along the coasts, and convergence along the cold front, models expect widespread precipitation over the Aegean. Although much stratiform clouds are possible given rather cool low-level air mass, at least along the cold front embedded thunderstorms seem to be quite possible. Given deep layer vertical wind shear in the range of 20 m/s as well as enhanced low-level vertical winds shear near the coasts, some thunderstorms may organize, but threat of severe weather is expected to remain quite low given rather stable boundary-layer and mainly embedded mode of convection. A few severe wind gusts are not ruled out. Chance of tornadoes seems to be not significant, as low-level veering seems to be not very favourable. Best potential exists near the Turkish coasts.

Further west, some more thunderstorms may develop in the range of the trough axis. Weak vertical wind shear and rather steep lapse rate may be favourable for isolated waterspouts, but overall threat seems to be not significant for a level 1.