Storm Forecast
Valid: Wed 11 Mar 2009 06:00 to Thu 12 Mar 2009 06:00 UTC
Issued: Wed 11 Mar 2009 00:46
Forecaster: PUCIK

SYNOPSIS and DISCUSSION

Relatively quiescent conditions concerning thunderstorm activity are expected in most of European continent. Western Europe will be affected by a mid-level ridge, slowly moving eastwards, whereas Eastern and Central Europe are under the trough, filled with cold airmass. Trough is expected to translate southwards, influencing the conditions over the Adriatics and Italy. Belt of strong mid and upper-level flow is surrouding its base. At the surface, large high will stall over Western Europe, whereas rest of Europe should experience extensive, but shallow complex of lows. A slight cyclogenesis is expected over the Adriatic / Ionian Sea, in the left exit region of the jet-stream. This area will be also the main focus for the thunderstorm activity.

As the trough filled with cold air will move over the warm SST, high lapse rates are expected to form over this region - reaching locally more than 8K / km. Also, synoptic-scale upward motion is predicted, associated with the PVA ahead of the trough, aiding in the destabilization. The overall instability release should be, however, marginal with MLCAPEs reaching several hundred J/kg. As cold profiles are indicated with temperatures at 500 hPa approximately -30°C, it will be easy for thunderstorm tops to exceed limit of -15°C and lightning is expected even with such weaker updrafts. As wind shear values will be quite low in the lowest 3 kms ( below 10 m/s), storms should stay mostly disorganised and no severe weather is expected. Sub-severe hail is possible, nevertheless, thanks to the very cold profiles. Thunderstorm activity will be most pronounced over Italy, Adriatic sea and will slowly translate southeastwards, by Thursday morning thunderstorms should form also over the Aegean Sea, close to the Turkish coast.