Storm Forecast
Valid: Sun 13 Oct 2013 06:00 to Mon 14 Oct 2013 06:00 UTC
Issued: Sun 13 Oct 2013 01:41
Forecaster: VAN DER VELDE

A level 1 was issued for the southern North Sea for waterspout type tornadoes.
A level 1 was issued for northern Russia mainly for severe convective wind gusts and tornadoes.

SYNOPSIS

A mid level cut-off low has installed itself over western Europe with its center over the southern North Sea. An occlusion is curled up around the center and extends from Belgium, UK to Denmark, Poland southward to Croatia. Over Poland, Slovakia and Hungary it acts as a cold front with a midlevel shortwave trough helping vertical motions. There is slight CAPE forecast in that area. CAPE is higher in the Mediterranean area between Tunesia and Albania, but a strong cap indicated in the GFS model appears to prevent storm development, otherwise the setup of SREH and instability around Tunesia would have been favorable for supercell storms. Weakly capped instability should develop mainly north of the Balearic islands and produce some thunderstorms. Also the frontal regions coming from the Atlantic can bring along some thunder.
A very dynamic, fast-moving depression moves from northern Scandinavia into northern Russia.

DISCUSSION

...southern North Sea...

Weak convective cell motion and low wind shear combined with good low level lapse rates can lead to spin-up of vorticity as waterspouts. Low level convergence and vorticity are strongly concentrated in this region.

...northern Russia...

A very low dynamic tropopause feature intrudes into the rear of the depression, where the lifting will be concentrated at the cold front. GFS develops low-level CAPE at the cold front, which likely will be consumed by a strongly forced convective line which may be shallow, but effective in transferring the very high wind speeds (25 m/s at 1-3 km AGL) to ground, producing severe gusts. 0-1 km shear vectors may reach 20 m/s which can favor the occurrence of brief damaging tornadoes.