Storm Forecast
Valid: Wed 15 Jul 2009 06:00 to Thu 16 Jul 2009 06:00 UTC
Issued: Tue 14 Jul 2009 21:39
Forecaster: GROENEMEIJER

A level 2 was issued for large parts of the Czech Republic, southern Poland and northern Austria, mainly for large hail and severe wind gusts.

A level 1 was issued for the Czech Republic, parts of Poland, Germany, and across the Alps, mainly for large hail, excessive rain and for severe wind gusts.

A level 1 was issued for parts of the Meshcher Lowland and the Volga River Basin, mainly for large hail.

SYNOPSIS

Wednesday at 0600 UTC, the evolution of convection across Europe will be determined by severeal vorticity maxima and minima embedded in a southwesterly jet over NW Iberia, France and the North European Plain. Per GFS, two vorticity maxima should intially be located across SW Germany and the Gulf of Genua, respectively. They are expected to move all the way toward Belarus, and to Hungary, during the course of the forecast period. Upstream, a sharpening trough over the northern Atlantic moves toward western Iberia. That system, however, will become more relevant to the weather on the European continent after this forecast period, that is later on Thursday.

Germany, Czech republic, Austria, Poland...

It is expected that elevated convection will be ongoing over parts of entral, southern and eastern Germany early Tuesday morning, which may locally lead to high precipitation rates. To the southeast of this activity - especially over northern Austria, the Czech Republic and SW Poland- temperatures should rise to 27-30 C again with dew point temperatures around 20 C. As a result, rather high CAPE should develop with values of 1500 J/kg MLCAPE or more. Surface-based storms are expected to from on the approach of the northernmost vorticity maximum, which could be relatively early in the day. The large CAPE values and moderate deep-layer wind shear of around 15 m/s suggests that multicells and perhaps a couple of supercells will probably occur. These will be capable of producing large hail, 2-5 cm in diameter, and some severe wind gusts. Further to the north, across northern Bohemia, central and eastern Germany, and central Poland the convection will likely be elevated and bear a threat of excessive precipitation rather than hail or wind.


The central and southern Alps...

Strong convective cells are expected across the Alps. They will bear a threat of -possibly large- hail, and heavy rain, warranting a level 1.


Parts of the Meshcher Lowland and the Volga River basin...

Alogn a southward moving cold front, thunderstorms are expected to develop near a line from Nizhny to near Rjazan. Moderate deep-layer shera and MLCAPE values of 1000 J/kg suggest that a small risk of large hail will be present.