CONVECTIVE FORECAST
VALID Wed 21 Sep 06:00 - Thu 22 Sep 06:00 2005 (UTC)
ISSUED: 20 Sep 20:50 (UTC)
FORECASTER: GATZEN

There is a slight risk of severe thunderstorms forecast across Aegean Sea and western Turkey

SYNOPSIS

Well-developed zonal flow is present over northern Europe ... and broad high spreads across Europe. Over Mediterranean ... a upper low is located over the Adriatic Sea ... yielding a strong westerly flow over southern and eastern Mediterranean. At lower levels ... stable airmass dominates the European high pressure system ... and slightly unstable maritime airmass is advected at its northern flank into British Isles and Scandinavia. Over central Mediterranean ... cool airmass has become unstable over the warm sea surface. To the east ... steep low-level lapse rates are present from Aegean Sea to Black Sea region.

DISCUSSION

...Aegean Sea and western Turkey ...
A cold front propagates eastward over Aegean Sea. In the range of the frontal boundary ... quite steep low-level lapse rates are present ... and low-level moisture is also likely along the front. GFS model output suggests CAPE in the order of 1000 J/kg over Aegean on Wednesday. ATTM, instability is expected to be weaker developed. However ... thunderstorms should go on in the range of the front ... and should spread eastward into Turkey, and Black Sea region. Thunderstorms that form will have a potential to be well-organized given 20+ m/s DLS over Aegean Sea, and western Turkey during the period. A few supercells and multicells are forecast ... capable of producing isolated large hail, severe wind gusts and intense precip. There is also a slightly enhanced chance for tornadoes given enhanced LLS ... and a few tornadoes/waterspouts are not ruled out.

...Black Sea region ...
Showers and thunderstorms are expected along mentioned cold front over Black Sea region. Relatively weak DLS is forecast east of the Mediterranean trough ... and chance for organized thunderstorms will be weaker than over Aegean Sea/western Turkey. However ... a few severe events are not ruled out, though ... given quite strong QG forcing and steep low-level lapse rates ... enhancing the potential for brief tornadoes.

...Central Mediterranean ...
In the range of the upper trough ... steep low-level lapse rates and increasing low-level moisture should lead to instability during the day. Thunderstorms should develop late in the period. Relatively weak DLS is forecast, and chance for severe thunderstorms should be low. A few waterspouts are not ruled out.

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