Storm Forecast
Valid: Mon 18 Aug 2008 06:00 to Tue 19 Aug 2008 06:00 UTC
Issued: Sun 17 Aug 2008 19:17
Forecaster: GROENEMEIJER

SYNOPSIS

Monday at 06:00 UTC the mid- and upper-level flow over Europe are meandering. A ridge stretches from north Scandinavia to the Caspian Sea. Upstream of the ridge axis, a cold front from Karelia via eastern Belarus to the eastern Balkans, which is followed by a mid-/upper-level trough. A slack ridge across western continental Europe is followed by a closed low just west of Ireland that slowly moves eastward reaching northern England on Tuesday morning.

DISCUSSION

Finland, Russian Karelia, Archangelsk, Vologda, Komi, Kirov...

A very warm air-mass over western Russia is present south of a warm front from central Finland to the southern Komi, and east of a cold front from eastern Finland via eastern Belarus to the eastern Balkans. Steep low and mid-level lapse rates are present within the warm-air mass. Only in vicinity of the frontal zones is considerable low-level moisture present. There, considerable amounts of latent instability can develop during the day, especially along the warm front. There, moderate deep-layer shear will possibly allow for a few organized storms with a threat of large hail, and possibly a few severe gusts.
A level 1 is therefore issued. Along the cold front, weak CAPE precludes the issuance of a threat level.

Western Europe...

Ahead of the approaching mid/upper-level low pressre system some warm air advection over the western European continent will cause a rise of low-level temperatures here. However, limited moisture should preclude the build-up of significant instability. A few, mostly non thundery showers are expected across the North Sea, Low countries and later across France and Germany. Across the British Isles in vicinity of the mid/upper low itself, a few showers will likely occur as well. Weak CAPE and shear strongly limit the severe potential here as well.