Storm Forecast
Valid: Thu 15 Jun 2006 06:00 to Fri 16 Jun 2006 06:00 UTC
Issued: Wed 14 Jun 2006 21:30
Forecaster: GATZEN

SYNOPSIS

A well-developed frontal boundary is present from Bay of Biscay to the northern coasts of Central Europe, Baltic States, and western Russia ... that is expected to undulate in response to complex upper flow regime. WAA is expected over France/western Mediterranean east of a cut-off low over SWrn Iberian Peninsula. Another, quite small upper low leads to CAA over the Channel, northern France, and Benelux/northwestern Germany, while WAA is expected to the east over Germany. A short-wave trough over Finland leads to CAA in the northern part of the frontal boundary. Over southeastern Europe ... large cut-off low remains digging eastward.

DISCUSSION

Eastern Spain

Well-mixed airmass characterized by steep lapse rates up to the 500 hPa level as indicated by latest Dar-El-Beida DAAG sounding advects northward east of quasistationary cut-off low. Over western Mediterranean/Spain ... rather moist low-level airmass is present as indicated by latest Gibralta and Murcia soundings ... where low-level mixing ratios of 12 g/kg were measured. Latest model output suggests CAPE in the order of 1000 J/kg. During the day ... diurnal heating and orographic lift as well as QG forcing underneath strong upper jet should lead to initiation over Spain. Especially southeastern Spain may be too dry for thunderstorms ... as quite dry low-level airmass indicated by Palma de Mallorca sounding should advect westward. Thunderstorms that form over central Spain may move eastward int eastern Spain/western Mediterranean ... where DLS will quickly become favorable for supercells. Large hail and severe wind gusts should be the main threat.

Central France, southern Benelux, and parts of Germany

Ahead of frontal boundary moving southeastwards in the range of cut-off low ... unstable airmass is present ... characterized by steep low-level lapse rates. As low-level moisture is poor over most of Germany ... CAPE was not too high. However ... in the range of the frontal boundary ... significant moisture has built as indicated by latest Trappes sounding ... and it is expected that CAPE in the order of 500 J/kg ... locally 1000 J/kg will realize from central France to central/northern Germany. Along the frontal boundary as well as along old outflow boundaries ... low-level convergence should lead to initiation. Although strong vertical wind shear should stay northwest of the frontal boundary ... enhanced DLS of about 15 m/s should be available to the storms that may become organized. Expect that a few multicells/supercells will form ... most significant threat will be large hail and severe wind gusts. Thunderstorms should cluster while moving eastwards into northern and eastern Germany ... where chance for severe storms will be significantly lower due to weaker DLS.