Storm Forecast
Valid: Wed 21 Dec 2011 06:00 to Thu 22 Dec 2011 06:00 UTC
Issued: Tue 20 Dec 2011 23:29
Forecaster: PUCIK

A level 1 was issued for Western Greece mainly for excessive precipitation.

SYNOPSIS

The main macrosynoptic features during the day will be a ridge over the Atlantic stretching up to Iceland and a deep, long-wave trough covering most of Europe. Trough is expected to slowly progress eastward during the day. Between these two features, strong northerly to northwesterly jet-stream has formed, with an active short wave trough at its cyclonically curved exit region. This trough is expected to induce cyclogenesis over the Central Mediterranean with active weather pattern, strong frontal system and also DMC occurrence. Surface low and attendant frontal system is forecast to move eastwards, affecting the Aegean region by Thursday morning. Other regions of Europe should see stable weather without any DMC.

DISCUSSION

... SE Italy, W Greece ...

With advection of high lapse rates airmass over this region in the prevailing NWly upper level flow and strong synoptic scale forcing, latent instability will likely develop in the warm sector of the surface low. 15-20 m/s of 850 hPa flow is forecast here and especially close to the warm front, strong lifting may result in a large mostly stratiform precipitation complex with embedded DMC. Such situation, especially over SE Italy or W Greece with flow impinging on the coast, as suggested by models, could lead to the enhanced potential of excessive precipitation. Limitation of this situation are relatively meager values of dew points. It looks that the best potential will exist over W Greece during late afternoon to evening hours and a marginal Level 1 is introduced here. SE Italy should experience less moisture and thus no Level is introduced atm even though threat will be non-zero. With cool vertical temperature profiles, small hail should be common in thunderstorms.