Storm Forecast
Valid: Wed 19 Jul 2006 06:00 to Thu 20 Jul 2006 06:00 UTC
Issued: Tue 18 Jul 2006 18:07
Forecaster: GATZEN

SYNOPSIS

Subtropic high ridges from northern Africa to southern Scandinavia. Warm airmass is present over most of western and central Europe in the range of this high. To the west ... Atlantic trough slowly spreads eastward into British Isles. Moderate southwesterly flow is expected to spread across western Europe during the period. To the east and north ... low geopotential is present over Scandinavia and eastern Europe ... where relatively cool and stable airmass will be present.

DISCUSSION

Western Europe

Ahead of approaching Atlantic trough ... a frontal boundary moves eastward reaching from western Spain to Bay of Biscay and further to western Great Britain on Wednesday, 18 UTC. To the east of this boundary ... warm airmass characterized by steep lapse rates and rather weak moisture will be present ... and models suggest increasing CAPE values due to height falls. Thunderstorms are expected to form along and east of this frontal boundary during the day due to weak QG forcing and daytime heating. Given weak vertical wind shear ... as well as high LCLs and rather weak CAPE ... organized thunderstorms are not expected to be likely. Given the well-mixed boundary layer ... strong wind gusts should be the most significant threat. Best potential for organized convection ... capable of producing large hail and severe wind gusts ... should exist over western Iberian Peninsula ... where upper level jet should be stronger and DLS should reach more than 20 m/s.