Storm Forecast
Valid: Mon 22 May 2006 06:00 to Tue 23 May 2006 06:00 UTC
Issued: Sun 21 May 2006 20:24
Forecaster: GROENEMEIJER

SYNOPSIS

Monday at 06:00...west of a broad ridge extending from Poland to Italy, a strong SWly mid level flow is present over western continental Europe. A warm plume extends from the Mediterranean into Scnadinavia. A cold core low centered south of Lake Ladoga moves eastward.

DISCUSSION

Benelux, NWrn Germany, Srn Denmark...

A very strong jet with wind speeds over 45 m/s at the 500 hPa level stretches over the area. On the cold side of a frontal zone extending approximately along a line from Kopenhagen to Bordeaux, some marginal instability is expected to build. Storms developing here, will likely be low-topped, but may, given the intense shear develop small bows. Main threat will be severe gusts caused by mixing of 25 m/s winds at 850 hPa down to the surface. Although low-level veering of the wind should be limited, the development of a few rotating storms is not ruled out and a marginal threat of tornadoes will exist as well.

NErn France, Nrn Switzerland, Srn/central/Ern Germany, Czech, western Poland...

Models suggest that east of extensive cloudiness associated with the frontal zone, some instability may develop and a few convective storms may result. 0-6 km bulk shear of about 25-30 m/s in combination with CAPE values of around 500 J/kg, may allow a few rotating storms/supercells to form. These will primarily pose a threat of large hail. The storms are expected, however, to cluster quite rapidly... especially because the shear vector and orientation of the front are parallel.