CONVECTIVE FORECAST
VALID 06Z WED 18/02 - 06Z THU 19/02 2004
ISSUED: 17/02 18:48Z
FORECASTER: GATZEN

General thunderstorms are forecast across eastern and central Mediterranean

SYNOPSIS

Long-wave trough remains over eastern Europe as amplified ridge builds over the northeastern Atlantic, yielding a northerly flow over western Europe. Embedded vort-maxima are placed over northern France and western Mediterranean. During the forecast period ... ridge axis should turn counterclockwise and new long-wave trough forms with an axis extending from eastern central Europe to the Iberian Peninsula. As a consequence ... vort-maxima over the Mediterranean will move eastward within rather zonal flow.

DISCUSSION

...Eastern Mediterranean...
Foci of convective activity will be two vort-maxima that affect the Mediterranean. Over Greece ... short-wave trough will move eastward leaving the forecast area in the morning hours. Model output suggests sinking due to cold air advection west of this trough, and thunderstorms should be limited to the extremely eastern forecast area. Today's soundings indicate moist boundary-layer and neutral or stable lapse rates. Tomorrow ... some thunderstorms are forecast along the coast of Turkey where some warm air advection is forecast. Showers and some thunderstorms may also occur over the eastern Mediterranean where cold front will propagate southeastward. However ... low-level shear and instability will be rather weak ... and organized thunderstorms seems to be not likely.

...Central Mediterranean...
Vort-max over the Balearic Isles will move ESEward and weakens. Avialable soundings show steep lapse rates in the boundary-layer and relatively moist airmass, yielding CAPE in the order of 100 J/kg. As the trough approaches ... synoptic scale upward vertical motion due to DCVA should lead to showers and thunderstorms. Weak instability and little shear are forecast and organized thunderstorms are not expected. However ... calm winds and rather steep lapse rates at low levels may be favourable for waterspouts at places where low-level moisture will be adequate.

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