Storm Forecast
Valid: Tue 25 Mar 2008 06:00 to Wed 26 Mar 2008 06:00 UTC
Issued: Mon 24 Mar 2008 19:56
Forecaster: TUSCHY

SYNOPSIS

A combination of a strong jet circling around the base of the intense upper-level trough, a phasing polar-/ subtropical jet on its tip and strengthening geopotential height gradients on its downstream side all together help to lift the upper-level trough slowly towards the north. This results in no drastic change for the forecast period but at least a modification of the assertive and disturbed weather pattern can be seen.
At the surface a cold airmass still covers most parts of Europe resulting in mostly stable conditions or diurnal driven convective activity . A strong depression over eastern Europe moves rapidly northward and strong dynamics help to bring the surface pressure down to 975hPa or lower.

DISCUSSION

.... Extreme western Russia ...

Main focus for a somewhat enhanced thunderstorm risk will be the northward moving cold front. Warm sector ahead of the front is moist and not too warm and as mid-levels cool down at least some low-end instability can be expected. Winds at 850hPa are at or above 25m/s which should support an isolated severe wind gust risk but at the moment it is questionable if deep convection can indeed form / maintain in forecast environment. Thunderstorm coverage seems to be too low for a level area right now.


... Germany, the Czech Republic and Austria ....

Upstream of the strong depression over eastern Europe, another surge of cold air overspreads those regions from the NW. Although already meager moisture gets mixed out over land betimes, very cold profilers indicate the chance to offset this negative fact . Right now we think that one area of enhanced thunderstorm chances will be over SE Germany, N-Austria and the Czech Republic and the other one over NW-Germany / the Netherlands as better LL moisture and very cold mid-levels overlap during the peak time heating. There is only a strong wind gust / sleet threat with those storms.

There exists a risk for a few thunderstorms over NE Germany and W-Poland but meager moisture could suppress the final thunderstorm coverage. We therefore decided to exclude those areas from the general thunderstorm area.


The other thunderstorm areas over the Mediterranean were issued due to some instability release but lack of moisture in those areas should keep coverage and intensity below severe weather criterion.
Mainly western Turkey could see an isolated large hail report if indeed a more persistent updraft can evolve.