Storm Forecast
Valid: Sun 30 Aug 2009 06:00 to Mon 31 Aug 2009 06:00 UTC
Issued: Sat 29 Aug 2009 23:10
Forecaster: SCHLENCZEK

No threat levels have been issued.

SYNOPSIS

On Sunday 06 UTC, an upper trough over the W Baltic Sea is forecast to shift eastward towards E Poland during the period. Over the central Mediterranean and the Balkan peninsula, geopotential heights will rise and a zone with very warm and unstable air over C Italy / Sicily moves out of the forecast area during the night hours. In the next few days, a plume of hot and moist air over Spain should overspread most parts of central Europe. The chance of severe thunderstorms should be very limited on Sunday.

DISCUSSION

...Central / southern Italy, Sicily, Balkans...

Diurnal heating will create about 1,5 kJ/kg weakly capped MUCAPE during the afternoon and thunderstorms may develop. Deep layer shear is limited to 10 m/s or less which should limit the threat of organized long-lived severe storms. Nevertheless, isolated large hail is possible given good thermdynamic conditions such as large MLCAPE above the freezing level. An isolated severe gust event and / or isolated heavy rain is also possible but overall threat is too low for a level 1 as QPF by GFS and WRF don't show very high precip sums.

...Baltic region, S Sweden, S Finland...

In the vicinity of the upper trough, quite warm SSTs and steep mid level lapse rates will result in some hundred J/kg CAPE in a very moist environment. Low level shear should be negligible but relatively strong SFC winds should limit the waterspout threat in this region. An isolated event is not discounted but overall probability is too low for a level 1. Convection should be most intense in the afternoon hours.