Storm Forecast
Valid: Mon 25 Dec 2006 06:00 to Tue 26 Dec 2006 06:00 UTC
Issued: Sun 24 Dec 2006 18:01
Forecaster: TUSCHY

SYNOPSIS

A persistent high pressure area, centered somewhere over Germany, will continue to affect most parts of western and central Europe.
The convective activity, which was seen during the past few days over parts of the western Mediterranean will slowly diminish as a result of an eastward propagating and therefore departing upper-level low pressure area. Strongest thunderstorm activity will slowly shift towards the central Mediterranean.
An outbreak of very cold air will occur over extreme western Russia, reaching the northern Black Sea region during the latter part of the forecast period.
Otherwise a quiet Christmas Day ( regarding thunderstorm activity ) can be expected.

DISCUSSION

....Black Sea...

A very cold airmass will cross the Black Sea region, where SSTs of up to 10°C can be found. Main concern will be the pretty dry boundary layer, which could support a large fetch area over the western part of the Black Sea.
Main focus for isolated thunderstorm development arises during the late evening and night hours, when the cold front will reach the area of interest. PBL modification and rapidly steepening lapse rates should support enough instability release for an isolated SFLOC report.

...Central Mediterranean...

Finally, the upper-level low will start its eastward shift as a result of an approaching upper-level trough NE of the system.
DLS will be enhanced south of Sicily and a broad area of instability release and DLS of 20m/s should support a locally augmented strong - severe wind gust risk . Lapse rates will stay steep enough and hence an isolated large hail threat can't be ruled out , where strongest shear and locally higher SBCAPE fields overlap.
Anyway, models show too much separation of the best instability and shear and hence no level-1 was issued.

Otherwise, shear will be too weak for storm organisation.