Storm Forecast
Valid: Wed 04 Oct 2006 07:00 to Thu 05 Oct 2006 06:00 UTC
Issued: Wed 04 Oct 2006 07:05
Forecaster: GATZEN

SYNOPSIS

Intense long-wave trough is present over western Europe, and strong upper jet curves around its periphery over western /northern Mediterranean and eastern Alpine region. Today, this trough is expected to weaken ... and strong jet streak moves to the eastern periphery of the trough. East of the trough, very warm air mass is advected into central Mediterranean, most of Balkans and Black Sea region. West of a cold front from western Mediterranean to Alpine region and further to Poland ... cool maritime air mass spreads into western and central Europe. This cold front quickly propagates eastward over eastern Europe in the wake of strong frontal wave ... while frontal boundary over northern Mediterranean will be slower.

DISCUSSION

Northern Mediterranean

Very warm air mass is present over parts of central Mediterranean. Latest soundings show impressive EML that spreads north-eastward into Balkans. Low levels are quite dry over most of Balkans ... and instability should remain weak. Over Mediterranean ... low level moisture is quite rich ... yielding CAPE values up to 1000 J/kg locally. Today ... upper jet streak moves across northern Mediterranean and Balkans ... yielding DCVA. Given some WAA along the frontal boundary especially over Adriatic east of weak surface low pressure over northern Italy ... QG forcing can be expected during the next hours. Best chances for initiation will be over northern Mediterranean ... where mid-level height falls will go on while low-level moisture is expected to remain given southerly surface winds east of the low. But additional thunderstorms are also likely in the range of the frontal boundary from south-western Mediterranean to southern Italy region. Given strong DLS over most of the region ... thunderstorms that form will have a potential to organize. Highest possibility of severe thunderstorms is forecast over Adriatic region ... where low-level buoyancy and LLS are strongest near the cold front due to rich low-level moisture and mid-level height falls south of the Alps. Expect that embedded severe thunderstorms will form during the next couple of hours ... with the potential of large hail, severe wind gusts and isolated tornadoes. Over western Mediterranean ... additional thunderstorms have formed in the range of the trough base. Given strong DLS ... these storms will also have a potential to organize ... and severe thunderstorms are not ruled out capable of producing severe wind gusts and isolated large hail. Given weak LLS ... chance for tornadoes should be rather limited.

Balkans

Dry low-levels and strong capping inversion is expected to inhibit initiation east of the cold front. Along the cold front ... convection will be most likely in the afternoon/evening hours as upper vort-max leads to DCVA. However ... thunderstorms are expected to be elevated given dry low-levels and strong capping inversion. Severe wind gusts should be possible with stronger storms in the evening hours ... but intensity of convection is quite unclear ATTM. Situation has to be monitored during the day.

Baltic Sea

Weak vertical wind shear and quite strong low-level buoyancy is present over Baltic Sea ... and it is not ruled out that a few water spouts will form underneath the base of the upper trough. Best potential seems to exist along the Swedish coast.