Storm Forecast
Valid: Tue 14 Oct 2008 06:00 to Wed 15 Oct 2008 06:00 UTC
Issued: Tue 14 Oct 2008 02:44
Forecaster: VAN DER VELDE

SYNOPSIS

A meandering westerly flow pattern occupies northern Europe, while stationary upper cut-off lows are active over southern Spain/Morocco and over the eastern Mediterranean Sea. Instability decreases in the former, while it increases in the latter area.
A low pressure area moving through Scandinavia into western Russia has a weak cold front extending via Poland into France, where a ridge of high pressure is present and slightly unstable profiles. An Atlantic disturbance affects Ireland and the UK, with possibly some elevated convection in its warm front.


DISCUSSION

...western Russia...

GFS simulates some marginal instability near the northern cold front and occlusion point region as the low moves into Russia. There is a moderate mid level PV anomaly following the occlusion, suggesting convection can be forced along the cold front, in an environment of 25 m/s DLS and more than 10 m/s LLS and low LCL heights. A linear system with gusts could develop, and a tornadic supercell could be part of this as well. SREH 0-1 and 0-3 km reach values of about 200 m2/s2.

...Crete, Rhodos, Turkish coast, Cyprus...

Destabilization is taking place as a shortwave trough sweeps northward around the east side of the upper trough during the afternoon. It is followed by a mid level cold front. GFS 18Z actually explodes just east of Crete with a probably unrealistic feature of very high SREH and LLS, but shear conditions are indeed favorable to supercells and mesoscale convective systems. DLS becomes strong east of 30°E, crossing MLCAPE values of probably >1500 J/kg (very steep mid level lapse rates).
Multiple storms/MCSs are likely to develop, with primary threats of (very) large hail and severe gusts. The coverage is thought to increase during the night. A level 2 may be required under the shear axis but this is mostly east of the map. Given large 0-3 km buoyancy, waterspouts can occur as well.