Storm Forecast
Valid: Tue 27 Oct 2009 06:00 to Wed 28 Oct 2009 06:00 UTC
Issued: Tue 27 Oct 2009 04:53
Forecaster: VAN DER VELDE

A level 1 was issued for the Aegean Sea and Crete mainly for waterspouts.

SYNOPSIS

Western Europe is largely dominated by ridge of high pressure, while an upper level trough extends from Finland to the Balkan. The only unstable airmass of significance resides over the eastern half of the Mediterranean, with the highest instability and mid level lapse rates south of Turkey.

DISCUSSION

...Aegean Sea and Crete...

The center of a shallow low pressure area lingers around Crete. Large 0-3 km CAPE as present in the 00Z Athinai sounding, and very weak flow and shear throughout a deep layer are favorable for stretching of ambient vertical vorticity in storm updrafts, producing waterspouts. This will be most likely where convergence zones (wind shift lines) are present and any capping weak. The latter could be an issue because current IR images do not show a large coverage of storms. GFS model predicts strongest convergence and low level contraction rate just over and north of Crete and southeastern Greek coast, providing focus for a level 1, but elsewhere spouts are not ruled out. There exists also a chance of local flash floods due to very slow storm motion (predicted <3 m/s).