Storm Forecast
Valid: Wed 18 Mar 2009 06:00 to Thu 19 Mar 2009 06:00 UTC
Issued: Tue 17 Mar 2009 22:35
Forecaster: PUCIK

SYNOPSIS

A blocking situation has evolved over Europe, with a large mid-level ridge stretching across eastern Atlantic and a deep trough lying on an axis from Scandinavia to northern Greece. Strong N/NW flow has established between these two features and a strong cold advection is underway across Central / SE Europe. Strong impulse will rotate around the base of the trough, supporting cyclogenesis over the Aegean and Black sea region.

DISCUSSION

...Belt extending from Hungary to Turkey...

Behind the cold front, a pronounced advection of cold maritime airmass will dominate the region. The airmass is characterized by steep lapse rates ( reaching 8K in the 2- 4 km layer), as suggested by numerous GFS model runs and 12Z Leba sounding. As of Tuesday 22Z, few weakly electrified thunderstorms have formed over Poland, Czech and Slovak republic. With the commence of surface heating during Wednesday, release of a few hundred of J/kg of MLCAPE is possible behind the frontal zone. Orographic support resulting from the northern flow impinging on the slopes should easily initiate convection. Due to the relative lack of moisture inthe airmass ( mixing ratio values under 4 g/kg) and marginal instability, only weakly electrified thundestorms are anticipated. The activity will be diurnally driven and therefore should quickly dimnish after the sunset. Convection forming from Greece to Turkey, will be connected to the progressing cold front. Although strong low and mid-level shear is forecast above Turkey, we are not issuing any threat level, as the instability / shear overlap will be almost non-existent.