Storm Forecast
Valid: Wed 15 Dec 2010 06:00 to Thu 16 Dec 2010 06:00 UTC
Issued: Tue 14 Dec 2010 22:52
Forecaster: PUCIK

SYNOPSIS and DISCUSSION

A prominent blocking, ometa type situation has established over Europe with a large cyclonic vortex at midlevels centered over Romania. Several short-wave troughs are forecast to rotate around it, the most prominent one entering the Northern Mediterranean by Wednesday morning. The trough is expected to amplify towards the south and contribute to the surface cyclogenesis by DCVA on its forward flank. As the trough will rotate around the vortex, a strong cyclonically curved jet is forecast over its southern flank. Another significant short wave trough is expected to cross the Norwegian Sea and during the day spread into the Northern Sea and Scandinavia propelled by a strong northerly jet-stream with the wind max exceeding 50 m/s at 500 hPa level.

Closer to the surface, a robust high pressure system, centered just west of Ireland as of 06 UTC Wednesday, will retreat to the west as the cyclogenesis will be observed over the Norwegian Sea and subsequently also over Scandinavia, in the exit region of a cyclonically curved jet-stream. A strong, rapidly moving cold front will be associated with this low, with the advection of arctic, unstable airmass behind it.

With the aforementioned cyclogenesis over the Mediterranean, a frontal zone is forecast to develop. Behind the cold front, a cold air advection over the relatively warm seas should increase the lapse rates and contribute to the slight destabilisation over the southern parts of the Mediterranean. Scattered showers and thunderstorms are forecast to form in this airmass. Towards the east, especially in the night and early morning hours of Thursday, a WAA along with a PVA above should contribute to the rising motion and destabilisation with marginal CAPE built-up. Such situation is forecast over Southern Greece, the Ionian, Aegean Sea and Southwestern coasts of Turkey. Despite the relatively favorable synoptic situation along with moderate to strong wind shear, instability should be too meager to allow for a more pronounced severe thunderstorm threat. However, a slight excessive precipitation risk will be valid for Southwestern Greece as the numerous rounds of storms are possible. In the next forecast period, a potential for excessive precipitation should increase over southwestern Turkey.