Storm Forecast
Valid: Sat 24 Sep 2011 06:00 to Sun 25 Sep 2011 06:00 UTC
Issued: Fri 23 Sep 2011 16:57
Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

There will be two cyclonic vortices, which affect N-Europe. One gradually approaches Iceland during the forecast whereas another one is centered over NE-Europe. Strong ridging in-between results in quiet and stable conditions over central Europe.

A much weaker upper trough over the W-Mediterranean slowly shifts eastwards and approaches Italy during the end of the forecast. As -14°C (500hPa) overspread the warm Mediterranean (SSTs 19-24 °C), widespread 500 J/kg MLCAPE evolve with local peaks up to 1 kJ/kg. However, shear is weak throughout the forecast and therefore, pulsating storms/weakly organized multicells are forecast. It is hard to highlight any specific area with a more concentrated thunderstorm coverage (despite NE-Spain) due to the diffuse forcing. Hence, broad and coarse thunderstorm areas were introduced. Thunderstorms keep going offshore during the night.

A few storms may develop during peak time heating over Estonia, as diabatic heating helps to destabilizes a mixed maritime air mass. 15-20 m/s winds at 850 hPa may allow strong to isolated severe wind gusts to accompany showers/sporadic thunderstorms. Thunderstorms rapidly decay during the evening hours as BL stabilizes/CAPE vanishes.