Storm Forecast
Valid: Thu 27 Dec 2007 06:00 to Fri 28 Dec 2007 06:00 UTC
Issued: Wed 26 Dec 2007 19:34
Forecaster: GATZEN

SYNOPSIS

A broad high stretches from Iberian Peninsula to eastern Europe. To the south, some upper level lows affect the Mediterranean. In the range of a cut-off over south-east Mediterranean, rather moist air mass is present south of Greece, while most regions are characterized by poor moisture. To the north of the high, intensifying cyclonic activity over northern Atlantic affects Scandinavia. An intense negatively tilted short-wave trough moves northward acoss western Scandinvia during the period.

DISCUSSION

Western Scandinavia

A moist and rather warm maritime air mass will affect western Scandinavia during the period. This air mass will likely be well-mixed in the range of a propagating trough that provides strong QG forcing. Additional forcing is expected along the western coast of Scandinavia due to upslope flow. Given some instability that will likely develop, showers and thunderstorms are not ruled out. Strong low-level vertical wind shear near the coast is forecast, and I do not rule out tornadoes. Best potential seem to exist in the late evening/night hours in the range of the trough axis. Additionally, some severe wind gusts may occur in the range of showers and thunderstorms.

South-east Mediterranean

Latest soundings indicate rich low-level moisture over southern Greece. In the range of an upper low moving slowly eastward, this air mass will likely destabilize, and thunderstorms are expected. Convective activity will likely concentrate on the area with best low-level moisture, while drier air mass will spread southward from Greece during the day, limiting the convective potential. However, some thunderstorms may organize during the day given easterly low-level winds and rather strong south-westerly winds aloft. Maybe a few mesocyclones capable of producing large hail and severe wind gusts may develop. One or two multicells seem to be more likely at this time, though, and potential for severe weather is expected to be rather weak.