Storm Forecast
Valid: Wed 26 Mar 2008 06:00 to Thu 27 Mar 2008 06:00 UTC
Issued: Tue 25 Mar 2008 22:13
Forecaster: GATZEN

SYNOPSIS

Broad and amplified polar trough is present over Europe, filled with rather cold air mass. An upper jet stream is located along the periphery of this trough from Bay of Biscay to northern Africa. A very strong upper jet streak is forecast to move into western Mediterranean at the southern flank of a short-wave trough. Another strong polar jet curves around an arctic trough present over Scandinavia and eastern/central Europe.

DISCUSSION

West Mediterranean

Cold air mass over the Mediterranean Sea has become unstable in the range of cold mid-level air mass and associated steep lapse rates of the warm water surface. Given westerly low-level winds, boundary-layer will be relatively moist, resulting in weak CAPE. Showers and thunderstorms are forecast given some QG forcing in the range of the cyclonic flank of the upper jet streak. Especially ahead of approaching very strong jet streak, strong QG forcing is forecast and models indicate cyclogenesis over west Mediterranean spreading into central Mediterranean during the period. In the range of the developing low, widespread showers and thunderstorms are forecast to the east of cold/dry strong Mistral winds developing over west Mediterranean during the period. Given strong deep layer vertical wind shear, a few mesocyclones or bowing lines are not ruled out, and isolated severe wind gusts may occur.

Central Europe

Given moderate vertical wind shear, some stronger graupel/snow thunderstorms my evolve into bowing lines and shallow mesocyclones, capable of producing vary large graupel and isolated strong wind gusts.