Storm Forecast
Valid: Sat 09 Apr 2011 06:00 to Sun 10 Apr 2011 06:00 UTC
Issued: Sat 09 Apr 2011 03:36
Forecaster: VAN DER VELDE

SYNOPSIS and DISCUSSION

High pressure over the North Sea region and a rather deep low pressure area (<980 hPa) over western Russia produces a strong northerly flow of cold air into the eastern Balkan area. Some CAPE is generated from Poland to Bulgaria, with cold enough tops over Romania along with lee convergence from the Carpathian mountains. While a jet lies over this region and the unstable airmass, causing high values of 0-6km deep layer shear, the low and mid level shear appear to be lacking, which reduces potential for rotation and large hail production. Gusty but probably not severe winds are expected in the larger area.

Elsewhere, in the indicated areas, and perhaps in isolated locations in Spain, models produce slight CAPE and spotty (or absent) convective precipitation signals under weak large scale lift conditions. The more interesting location of these is the Slovenian-Croatian area where albeit very weak instability both SREH and deep layer shear are enhanced to support rotating updrafts, and the approaching cold front encroaches a notch of warm air remaining in the lee of the Alps. In the case a storm forms there it may produce an isolated, marginal large hail event.

As far as the higher potential of severe weather (tornadoes and severe wind gusts) goes, eastern Ukraine and surrounding Russia show very high deep and low-level shear values, but instability fields appear weak or absent in the shear region. Forcing is very strong, though, and may initiate a strongly forced convective line.