Storm Forecast
Valid: Wed 05 Mar 2008 06:00 to Thu 06 Mar 2008 06:00 UTC
Issued: Tue 04 Mar 2008 22:35
Forecaster: GATZEN

SYNOPSIS

Quite strong cold air outbreak over central Europe spreads into west Mditerranean Sea. With strong Mistral winds, cold air mass reaches the African coast on WED morning. Along the eastern cold front, cyclogenesis is expected during the period, while upper trough cuts off. The northern trough axis moves eastward over Poland. To the north, increasing DAVA is expected from western Europe to Germany and further to Black Sea region. At low levels, cold air mass is present over most of Europe. Steep lapse rates are present in the range of the upper trough over north-eastern Europe as well as over west Mediterranean, where strong CAA is forecast. Over the relatively warm sea surface, low-level moisture is forecast to increase, leading to some nearly uncapped CAPE. Along the frontal boundary, WAA is forecast that will affect southern and central Italy. Over south-eastern Europe, quite warm air mass is present that spreads northward.

DISCUSSION

Southern Adriatic

A quite interesting convective set-up is expected to evolve over southern Adriatic region. Ahead of the cold front that slows down over Italy and starts to form frontal waves, a tongue of relatively warm and quite moist low-level air mass spreads northward. From the south, rather steep mid-level lapse rates are forecast to spread into the region, where CAPE will likely develop during the period. While low-level convergence is expected to intensify, as some frontal waves form and start to deepen, increasing south-easterly winds will likely advect the moist air mass into southern Italy during the period. With strong southerly winds aloft, at least moderate low-level vertical wind shear and about 100 J/kg 0-1 km SRH are forecast to develop. During the day, upper jet streak curving around the developing cut-off low will affect the region, and some QG forcing is likely. Expect that thunderstorms will initiate along the cold front as well as over southern Italy during the day that will move to the north-east. Given rather strong vertical wind shear, mesocyclones are expected to develop, capale of producing isolated large hail and severe wind gusts. Tornadoes are not ruled out especially near the coasts where low-level SRH and convergence may be strongest. Convective activity is expected to go on during the night hours given increasing QG forcing in the rnage of the upper jet streak and associated low-level frontal wave. Thundrstorms may merge into a MCS, while threat of tornadoes and hail is expected to remain.

West Mediterranean

Cold and rather dry air mass will destabilize over the Mediterranean Sea in the range of the upper cut-off low. Weak dep layer wind shear and weak veering profiles will be present, and mesocyclones seem to be not very likely. Showers and thunderstorms that form may produce isolated severe wind gusts due to strong northerly flow and good low-level lapse rates. To the south, chance for waterspouts increases due to weaker winds and better low-level lapse rates over the warm sea surface.