Storm Forecast
Valid: Thu 20 Jul 2006 06:00 to Fri 21 Jul 2006 06:00 UTC
Issued: Wed 19 Jul 2006 22:38
Forecaster: DAHL

SYNOPSIS

Rather weak and broad upper WSWLY flow persists across western and central Europe at the E periphery of stationary long-wave upper trough over the Atlantic. Farther SE ... weakening upper low should cover the Ionian Sea and Greece. Vigorous large-scale upper trough is present over NE Europe and W Russia ... with associated SFC low promoting strong CAA across this region at low levels. Otherwise ... SFC pressure field will be rather flat on Thursday.

DISCUSSION

France ... Benelux ... Germany

Plume of rather moist low-level air ... currently extending across Iberia ... France and portions of the S UK ... is expected to advect NEWD into E Germany by Friday early morning. CAPEs in this air mass should be on the order of 1000 J/kg ... though locally somewhat higher CAPEs may exist where moisture is richer than what has been revealed by Wednesday's 12Z soundings ... also the moisture may locally be mixed out to result in inverted-V type profiles. GFS' lapse-rate and CAPE fields suggest that this may especially be the case across E Germany and W Poland.

Several weak short-wave trough should travel across France and Germany into Poland on Thursday ... the strongest one crossing NRN France in the morning/midday hours ... moving into Benelux and W Germany during the evening/night.

Indications are that TSTMS will (re-)develop ahead of the short-wave trough over N France ... and spread into Benelux/Germany in the evening/night hours. Storms should congeal into one or more MCSs which should cross NW Germany and the S North Sea during the overnight hours. Mid-level flow of about 15 m/s should provide sufficient shear for some hail ... which may locally reach severe limits ... as well as for strong outflow winds.

Farther east ... isolated TSTMS could develop during peak-heating hours. If deep/dry CBLs will indeed be in place ... some very gusty outflow winds may occur ... but it seems that it will be too isolated for a categorical risk ATTM.