Storm Forecast
Valid: Thu 04 Aug 2011 06:00 to Fri 05 Aug 2011 06:00 UTC
Issued: Wed 03 Aug 2011 21:46
Forecaster: GATZEN

A level 1 was issued for Italy and the Balkans mainly for large hail.

SYNOPSIS

A northern Atlantic trough is associated with a rather strong westerly flow that is directed to western Europe. The delta of this jet is located over central Europe. South-westerly low-level winds will advect moderately warm and rather moist air masses into western and central Europe ahead of a cold front spreading across the British Isles.

DISCUSSION

Italy and the Balkans

Westerly winds will advect a humid air mass into Italy and the Balkans that will destabilize due to diurnal heating. CAPE values are expected to exceed 1000 J/kg near the base of an eastward moving short-wave trough, where mid-level lapse rates are relatively steep. Upslope flow and low-level convergence along sea-breeze fronts will assist initiation and thunderstorms are forecast. The large-scale vertical wind shear will be weak and most convection is forecast to be unorganized and short-lived. However, stronger pulse storms are not ruled out to produce large hail and excessive precipitation. Convective activity is forecast to decay in the evening hours.

Southern and eastern Germany

Along a frontal boundary moving eastward across Germany, very moist low-level air is forecast on Thursday. Thunderstorms are forecast to produce locally excessive rain given the slow storm movement and high water content of the air mass. The threat seems to be too low for a level 1, though.