Storm Forecast
Valid: Thu 22 Mar 2007 06:00 to Fri 23 Mar 2007 06:00 UTC
Issued: Thu 22 Mar 2007 02:27
Forecaster: VAN DER VELDE

SYNOPSIS

A large upper cut-off low pressure system remains stationary over Europe (S-Scandinavia to Algeria, Spain to W-Turkey). Two cores circle around inside this system: one moving over Poland into Germany, the other moving from Italy to the Aegean Sea. The cold airmass aloft guarantees widespread thundery convection (with probably a few waterspouts) over the relatively warm Mediterranean Sea. More isolated thunder is expected over the Balkan up to Poland.

...Aegean Sea...

During the second half of the period, a narrow plume of warm theta-e over the southern Mediterranean/Aegean Sea is re-intensified by strong advection of Saharan warm air, creating a small wave. Under the jetstream there is over 30 m/s deep layer shear, >15 m/s low level shear and strongly veering winds with height. If surface-based convection could develop, a strong potential exists for storm rotation and threats of large hail, a tornado, and severe gusts... but GFS-12Z and 18Z runs show hardly signs of deep instability and a band of rather weak 2-4 km lapse rates. Most-unstable parcel parameters come to higher cloud tops in the same area, indicating some chance of elevated convection which would be mostly harmless as it would not profit from most of the shear and helicity. However, the situation and any developing convection should be monitored closely.