Storm Forecast
Valid: Sun 22 Sep 2013 06:00 to Mon 23 Sep 2013 06:00 UTC
Issued: Sun 22 Sep 2013 04:48
Forecaster: VAN DER VELDE

A level 1 was issued for Latvia, Lithuania and Belarus mainly for severe convective windgusts and tornado chances.

SYNOPSIS and DISCUSSION

High pressure from Bristish Isles to the Balkan keeps a wide section of Europe under calm conditions. North of the high, a depression slips via Scandinavia into Russia and the Black Sea region. Over the Baltic region a dynamic tropopause (PV) feature curls up at the nose of a strong jet, indicative of rapid cyclogenesis. CAPE is predicted by GFS in the cold sector and at the cold front after 21Z, which will likely develop into a strongly forced convective line bringing mainly severe wind gusts (25 m/s wind present between 1-3 km AGL), but also tornadoes are not ruled out given very large circular low-level hodographs. More than 20 m/s 0-1 km shear is predicted during the night.
Pressure is also low over the southern Mediterranean Sea, where an upper trough passes followed by low level cool air advection from the north. There is only moderate deep layer shear caused by strong upper level winds, but low to mid levels are weakly sheared. Waterspout tornadoes are not ruled out, as is an isolated large hail event.
Waterspouts are also likely to occur over the Black Sea where a weak cold front is passing.