Storm Forecast
Valid: Sat 31 May 2008 06:00 to Sun 01 Jun 2008 06:00 UTC
Issued: Fri 30 May 2008 21:37
Forecaster: GROENEMEIJER

SYNOPSIS

On Saturday, the mid-level flow is characterized by a cut-off low over the Iberian Peninsula that moves eastward, a stationary omega-shaped ridge with its centre over the Kattegat and a longwave trough extending southwestward from the Moscow region. A relevant minor feature is a vorticity maximum that is forecast to cross the Alps from south to north.
Warm air resides along a thermal ridge from the Aegean Sea region over the Balkans and eastern parts of Germany towards southern Scandinavia, whereas somewhat cooler, maritime air resides over southwestern Europe and cold, dry air over the northeast.

DISCUSSION

Germany...

Rather complicated forecast as the timing of a large convective system travelling northward on Friday did so further east and earlier than numerical had forecast. Furthermore, the effects of the vorticity maximum over the Po Valley that should move into southern Germany is unclear.
Present indications are that a convergence zone will extend from near Bremen to the Bayrischer Wald and that new convective development will take place along this line.
The development of another MCS, likely in the afternoon travelling in northwesterly direction to the Frisian Islands is possible. There is too much uncertainty though to warrant a level 2 at the moment. Generally, flash flooding and large hail will be the highest threats.

To the west of the primary convergence zone, additional storm development appears likely directly ahead of the upper-level vorticity maximum. There, some storms may be able to produce some large hail as well.

SW France, N Spain...

Although vertical wind shear is forecast to be weak to moderate only, about 1000 J/kg MLCAPE is forecast to form in vicinity and north of the mid/upper-level low. These storms should be able to produce a few localized large hail events. Even an isolated weak landspout-type tornado cannot be ruled out.

Czech and Slovak Republics, Eastern Austria, much of the Pannonian Plain, Transsylvania and western Bulgaria...

Scattered storm development is expected in this level 1 area, where steep mid-level lapse rates should enable storms to produce some marginally large hail locally, despite the vertical wind shear being weak.
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