Storm Forecast
Valid: Mon 30 May 2011 06:00 to Tue 31 May 2011 06:00 UTC
Issued: Mon 30 May 2011 03:37
Forecaster: DAHL

A level one threat has been issued across NW France and S Belgium for marginally severe hail/winds.

A level one threat has been issued across SE Spain and the SW Mediterranean for large hail and severe winds.

A level one threat has been issued across W Greece mainly for excessive raifall.

SYNOPSIS

An amplifying Atlantic upper trough and an attendant SFC cold front are expected to progress into the Channel region / western continental Europe by early Tuesday.
A weak frontal wave is anticipated to form along the front over the S British Isles early in the period and track into southern Scandinavia. A broad region of low geopotential persists over SE Europe.

DISCUSSION

... W France into W Germany ...

It seems that weak instability will materialize in the warm-sector air mass from France into Germany, east of the cold front.
Shear profiles may become marignally supportive of severe thunderstorms from NW France into Benelux/W Germany.
However, forcing for vertical motion looks to be weakest where shear is strongest ... with a Goldilocks zone over NW France and S Benelux.
Expect sporadic marginally severe hail/winds to be the main threats. There is a very conditional threat also of tornadoes,
should storms form over NW Germany where about 10 m/s LLS are simulated. However, current thinking is that storms will fail to initiate over that region.

... Iberian Peninsula ... SW Mediterranean ...

Weak DCVA and diurnal heating should aid in widespread thunderstorm development over Iberia. DLS will exceed 20 m/s over the western portions of the peninsula. Main threats should be large hail and severe wind gusts, as well as locally excessive rain.

... SE Europe ...

Scattered diurnally driven storms should form over the SE portions of the forecast area in a weakly unstable,
weakly-capped, and weakly sheared air mass. Although the organized severe threat is minimal with this activity, very
sporadic large hail/severe winds could occur, presumably due to local/unresolved modifications of the storm environment.
GFS suggests that Greece may see locally excessive rainfall, warranting a LVL1 threat.