CONVECTIVE FORECAST - UPDATE
VALID 15Z FRI 30/04 - 06Z SAT 01/05 2004
ISSUED: 30/04 15:32Z
FORECASTER: GATZEN

There is a slight risk of severe thunderstorms forecast across Benelux

General thunderstorms are forecast across see previous outlook

SYNOPSIS

Closed upper level low has formed over southwestern Europe. To the east ... weak ridge is present over southeastern Europe. Between these two systems, warm and moist airmass remains over central and southeastern Europe and central Mediterranean. At low levels ... low pressure system is forecast over western France ... with a cold front extending from southern England to southwestern Germany. Widespread diurnal convective activity can be expected during the forecast period, as several vorticity maxima and relatively unstable airmass are present over the forecast area.

DISCUSSION

...Benelux, western Germany, eastern France...
Along and ahead of the cold front ... rather moist airmass is present over Germany/ Benelux. Aloft ... steep lapse rates are present due to latest ascends (Essen). During the last hours substantially instability has formed ... with CAPE probably reaching 1000 J/kg. Showers and thunderstorms are forming and slowly moving northeastward. Moderate low level wind shear and deep layer wind shear increasing to the west should be sufficient for organized convection. Some thunderstorms may be strong and some mesocyclones are expected. Large hail, damaging wind gusts and probably a tornado or two are not ruled out. North of the Alps ... chance for isolated large hail will be enhanced as mid-level steep lapse rates should form due to föhn.

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