Storm Forecast
Valid: Mon 17 Nov 2008 06:00 to Tue 18 Nov 2008 06:00 UTC
Issued: Sun 16 Nov 2008 16:49
Forecaster: TUSCHY

SYNOPSIS

Strengthening high pressure over the eastern Atlantic arches upward while blocking the predmoinant upper zonal flow pattern over the N-Atlantic. Geopotential heights begin to fall over most parts of N/CNTRL and E- Europe during the day and mark the beginning of a much colder period for most parts of Europe. Weakening upper trough over the central Mediterranean shifts eastwards, before re-gaining strength during the night hours, as geopotential height falls reach the Mediterranean. A few lightning strikes are possible during the passage of very cold upper trough over NW Norway, 00Z onwards.

DISCUSSION

... Crete, S-Aegean Sea ...

As upper trough draws near from the west during the day, atmosphere at all levels starts a gradual cool-down. SSTs in the upper tens/lower twenties still present, so expect a fair amount of instability, especially at lowest 2-3km. Background flow in general remains weak with DLS of 10-15m/s despite numerous short-lived flare-ups as small-scale disturbances pass by. BL airmass remains humid and LCLs low, so risk of waterspouts will be enhanced over an extensive area, especially if local convergence zones can set up. Degree of LL CAPE release and locally enhanced DLS even hint on an isolated strong tornado event. Despite overall weak shear, DLS of near 20m/s over Crete, a lowering WBZ level and some modest mid-level CAPE release indicate a risk of large hail with stronger storms. Overall, parameters look fine for numerous tornado/hail events but we first want to wait for new model data before updating.