Storm Forecast
Valid: Wed 18 Nov 2009 06:00 to Thu 19 Nov 2009 06:00 UTC
Issued: Tue 17 Nov 2009 22:51
Forecaster: PUCIK

+ + + CORRECTED 08:25 UTC + + +

SYNOPSIS

In comparison with the previous period, ridging is forecast over the Mediterranean during Wednesday with the northern extent of the ridge slowly building towards Central Europe. Significant cyclonic vortex will persist over the Eastern Atlantic with surface pressure below 960 hPa just south of Iceland. Several vorticity maxima rotate around the large low. Rather intense disturbance is forecast to cross the North Sea and Baltic Sea, in the left exit region of the jet. Cyclogenesis is expected in this region with strenghtening low level winds.

Generally, very stable conditions are predicted across whole Europe with just two areas having a slight risk of thunder. First one lies between Morocco and SW Spain/Portugal where under a mid-level cold-core low some instability release is predicted. Surface convergence might initiate thunderstorms in moderate CAPE / minimal CIN environment. Another one will be in a maritime polar airmass behind the cold front during the Wednesday night to the north of Scotland, but chances of thunder are so low that no lightning area is issued.

DISCUSSION

... North Sea, Baltic Sea, Benelux Countries, Northern Germany, Denmark...

Under cyclonic 50-70 m/s jet-streak at 300 hPa, cyclogenesis is forecast with strong pressure gradients expected to the south of the surface low. Flow at 850 hPa might reach 35 m/s, as simulated both by GFS and ECMWF models. Widespread severe wind gusts are possible especially over the sea and near the coastal areas, reaching 25-30 m/s with chance of hurricane force gusts over the North Sea and adjacent coasts (Benelux, Germany, Denmark). However stable conditions are forecast and in spite of strong forcing and favorable kinematic setup, only weak convection should occur, not contributing to the overall wind gust strenght. Due to this fact Level 1 for this region is not warranted.