Storm Forecast
Valid: Wed 30 Aug 2006 06:00 to Thu 31 Aug 2006 06:00 UTC
Issued: Tue 29 Aug 2006 19:07
Forecaster: GATZEN

SYNOPSIS

Low geopotential covers north and central Europe ... and cool maritime airmass has spread into western and central Europe. A very strong upper jet curves around the European trough ... and embedded vort-maxima/jet streaks yield strong DCVA. Warm but rather dry airmass is present from southern Balkans to Black Sea region.

DISCUSSION

Adriatic, southern Balkans, Black Sea region

Latest soundings do not indicate adequate instability over most of SErn Europe ... with quite dry boundary-layer from northern Adriatic to Black Sea region. It is questionable that sufficient moisture will develop during the period ... best potential seems to exist over Aegean and Black Sea. However ... locally increasing moisture due to warm water surface and resulting CAPE is not ruled out and is shown by latest GFS model output over northern Adriatic and parts of southern Balkans. Thunderstorms should be most likely in the range of a strong upper vort-max moving across Greece, Aegean, and Black Sea region during the day ... providing strong DCVA and QG forcing. Latest models show a deepening surface low over southern Balkans that is forecast to move into western Black Sea. Thunderstorms that will form near the surface low may be well-organized given strong vertical wind shear. Severe wind gusts should be the main severe threat given steep low-level lapse rates. Isolated large hail will be also possible with the stronger storms. Limiting factor will be weak instability, though, and later ascends may warrant an upgrade/downgrade later on.

Western Russia

Strong cyclogenesis over western Russia is expected. Occluded frontal system will include rather moist and unstable airmass present over south-western Russia. Although low-levels should be stable as indicated by latest GFS ... a few surface-based storms may develop in a region with high helicity/vertical shear near the occlusion. However ... current thinking is that stratifom rain and embedded thunderstorms will inhibit insolation. Most significant severe threat should be non-supercell tornadoes due to low LCL heights and strong low-level vertical wind shear.