CONVECTIVE FORECAST
VALID Wed 28 Sep 06:00 - Thu 29 Sep 06:00 2005 (UTC)
ISSUED: 28 Sep 07:43 (UTC)
FORECASTER: GATZEN

SYNOPSIS

Blocking high over northeastern Europe remains, as northern Atlantic long-wave trough evades into northern and central Europe. Over Mediterranean ... weak upper lows move eastward, and Atlantic high pressure system ridges eastward into western Mediterranean. At lower levels ... relatively warm airmass is present from Mediterranean to eastern central Europe and eastern Scandinavia. This airmass is expected to be slightly unstable over eastern Mediterranean and from eastern Balkans to eastern Scandinavia ... and thunderstorms have already formed over the Baltic States. Weak veritcal wind shear should be present during the next hours. Weak QG forcing and weak instability are also expected ... and chance for severe thunderstorms is foreast to be low. To the west ... a cold front from Baltic Sea to northwestern Germany and Bay of Biskay is expected to propagate eastward during the period. Cold maritime airmass that advects into North Sea region is forecast to destabilize in the range of a short-wave trough/vort-max that travels eastward over the North Sea and Baltic Sea during the period. Showers and thunderstorms should go on and spread eastward in the range of this short-wave trough. Given weak vertical wind shear, chance for severe thunderstorms should be low. Further west ... relatively intense low is forecast over northern British Isles. Associated frontal system should cross southern British Isles on late Wednesday. Warm maritime airmass SE of the cold front is forecast to be slightly unstable due to quite moist boundary layer airmass ... and strong forcing along the cold front should lead to showers and isolated thunderstorms. Moderate DLS and quite strong LLS are expected over southern British Isles and The Channel region ... and given moist low-level airmass and low LCL heights ... a few tornadoes may be possible. Allover threat should be too low for a SLGT.

DISCUSSION

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