Storm Forecast
Valid: Sat 13 Oct 2007 06:00 to Sun 14 Oct 2007 06:00 UTC
Issued: Fri 12 Oct 2007 16:32
Forecaster: TUSCHY

SYNOPSIS

The winter is on advance and this can be noticed not only on calendar, but also when having a glance on the weather maps.
A wavy upper-level streamline pattern is currently present and affects the European weather.
This pattern, showing up like an omega, is characterized by two troughs, one over the northern Atlantic Ocean and another one centered over the western Ukraine and in-between a stout ridge over western Europe.
This constellation supports the first more serious advection ( I don't want to use the word 'outbreak' ) of cooler air towards the south, affecting all areas from Estonia to northern Greece with cooler conditions.
Otherwise, western Europe, the Mediterranean and the extreme eastern European regions in our forecast area stay warm.


DISCUSSION

... South-central Mediterranean and NE-Algeria / Tunisia...

This environment is neither fish nor fowl.
Geopotential heights rise marginally during the forecast period but temperatures at 850hPa cool down one or two degrees.
The main focus for some activity will be along and especially south of a slowly southward moving frontal boundary. Dewpoints to the north stay in the lower tens and even with mixing due to the warm Mediterranean, no significant instability release can be expected, keeping the thermodynamic stratification of the upper atmosphere in mind.
Over NE-Algeria / Tunisia ( and further towards the south, but not in our area of responsibility ), better boundary layer moisture, steeper mid-level lapse rates and somewhat better shear (DLS of 15-20m/s although mostly speed shear ) favor an enhanced chance for organized storms. The main concern will be an isolated tornado threat due to locally augmented LL shear along the front and signals of good 0-3km CAPE release.

...Parts of the Black Sea...

A southeastward racing cold front will be the main focus for scattered thunderstom activity. No significant severe weather threat is currently expected, as best shear and instability fields don't overlap and as shear vector stands nearly parallel to the orientation of the cold front . Repeated thunderstorm development along the front is anticipated with gusty winds being the main threat.
We issued a marginal level-1 as a few storms could profit of stronger shear ( 0-3km of 15-20m/s ) along the front.
A more serious risk for severe thunderstorms develops further towards the east but again, this is out of our area of responsibility.

...SW Turkey...

Better shear and moderate instability release will be present and a few storms could organize, producing gusty winds and isolated large hail.
Thunderstorms over western Turkey could produce a few severe wind gusts during the night hours, as DLS increases from the north.