CONVECTIVE FORECAST
VALID 06Z WED 24/12 - 06Z THU 25/12 2003
ISSUED: 23/12 23:00Z
FORECASTER: GROENEMEIJER

General thunderstorms are forecast across parts of the central and eastern Mediterranean

SYNOPSIS

A large mid/upper low pressure area filled with cold air is expected to move eastward from southern Italy to 300 km west of Crete during the forecast period. A zonal jet stream is blowing over the northern British Isles and southern Scandinavia. A strong but somewhat weakening ridge is forecast over southwestern Europe.

DISCUSSION

...western and southwestern Turkey...
A cold front is expected to be nearly north-south oriented over the Aegean Sea the the beginning of the forecast period. Soundings indicate the air-mass ahead of the front is approximately moist-adiabatically stratified above the boundary layer. Nevertheless, thunder is occurring in some places. During Wednesday evening, as the front approaches southwestern Turkey, a weak upper vort max is expected to enhance rising motions ahead of the front so that an increase in coverage and intensity of thunderstorms is expected. Low-level winds are expected to increase... at 850 hPa wind speeds near 30-45 knots are expected. Locally, boundary layer wind shear could be in excess of 20 knots. Given that instability is low, the chance of rotating updrafts seems to be not too big. Nevertheless, if they occur, a few strong gusts or large hail may occur. This does not, however, warrant a categorical risk.

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