Storm Forecast
Valid: Thu 02 Apr 2015 06:00 to Fri 03 Apr 2015 06:00 UTC
Issued: Thu 02 Apr 2015 06:02
Forecaster: GATZEN

A level 1 was issued for south-eastern Germany, the Czech Republic, parts of Austria, and Hungary mainly for severe wind gusts and to a lesser extend tornadoes.

SYNOPSIS

A broad and amplified trough is situated across eastern and central Europe, leading to a strong north-westerly flow that extends from western Europe to the east Mediterranean. Embedded in that flow, two strong vort-maxima rotate around the base of the trough, one across the Black Sea, the other from Germany into the central Balkans. At low levels, relatively dry air masses are present across eastern Europe, except for tongues of moist air that are advected ahead of the vort-maxima. Moist air affects western Europe and the Mediterranean. An overlap of moisture and steep lapse rates is most likely ahead and near the base of the vort-maxima, and thunderstorms are expected across Romania and the Ukraine as well as from Germany into the northern Balkans.

DISCUSSION

South-eastern Germany into Hungary

A tongue of moist air had spread into south-eastern Germany ahead of the approaching vort-max, indicated by dewpoints up to 3 degree Celsius. Ascend ahead of the vort-max results in steepening lapse rates overlapping with this moisture and CAPE is expected. Frontogenesis is underway across eastern Germany, where a narrow cold-frontal rain band formed. It will progress south during the period. It is quite unclear if the band can persist when it moves into the Czech Republic and southern Germany. However, a re-organization is forecast due to diurnal heating and a better overlap of moisture and lapse rates during the noon and afternoon.

Along the narrow cold frontal rain band, thunderstorms are possible across the Czech Republic, south-east Germany, Austria, and Hungary. 0-1 km vertical wind shear around 12 m/s and 0-3 km vertical wind shear up to more than 25 m/s indicates that chance of organized convection, and a tornado as well as severe wind gusts are not ruled out. Ahead of the narrow cold-frontal rain band, severe wind may be possible to the north of the Alps that are not related to deep moist convection.

In the wake of the cold front, well-mixed polar air masses allows for showers and thunderstorms. Increasing low-level vertical wind shear in the evening hours indicates a potential of some better organized thunderstorms, and isolated severe wind gusts and a tornado are not ruled out.