VALID 21Z FRI 29/11 - 06Z SAT 30/11 2002
ISSUED: 29/11 20:32Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE WESTERN AND CENTRAL MEDITERRANEAN SEA.

SYNOPSIS

MAIN FEATURE THIS PERIOD IS UPPER LONGWAVE TROUGH ATTM COVERING MUCH OF WRN EUROPE AND THE NRN MEDITERRANEAN... WHICH IS PROGGED TO CONTINUE TO SLOWLY DIG SOUTH. AT LOW LEVELS...HIGH PRESSURE/CONTINENTAL ARCTIC AIRMASSES COVERING NE PARTS OF EUROPE. OFF THE IBERIAN COAST ANOTHER HIGH PRESSURE AREA IS RESIDING OVER THE E ATLANTIC... LEAVING CENTRL EUROPE IN BROAD/WEAK LOW PRESSURE TROUGH WITH SEVERAL EMBEDDED LOW-LPRESSURE CENTERS ATTM AFFECTING FRANCE AND PARTS OF THE MEDITERRANEAN. NARROW TONGUE OF RATHER STABLE MARITIME SUBTROPICAL AIR ANALYZED OVER THE CNTRL MEDITERRANEAN AHEAD OF COLD FRONT WHICH IS ASSOCIATED WITH THE MAIN MEDITERRANEAN LONGWAVE TROUGH.

DISCUSSION

...WESTERN AND CENTRAL MEDITERRANEAN...
WV IMAGERY AS WELL AS NUMERICAL UPPER AIR ANALYSES SUGGEST TWO VORTICITY MAXIMA AT THE PERIPHERY OF THE MAIN TROUGH... SUPPORTING TWO REGIONS OF RATHER POORLY DEVELOPED ENHANCED CUMULUS IN THE POSTFRONTAL ENVIRONMENT OVER FRANCE AND THE W MEDITERRANEAN SEA RESPECTIVELY. LIGHTNING NETWORK INDICATES A FEW DISCHARGES WITH THE ACTIVITY OVER THE W MEDITERRANEAN SEA. ADDITIONAL TSTMS MAY REDEVELOP AHEAD OF THE FRENCH VORT MAX AS IT ENCOUNTERS WARM MEDITERRANEAN SEA LATE TONIGHT/EARLY SATURDAY MORNING. 0-6 KM SHEAR APPEARS TO BE ON THE ORDER OF 50 TO 70 KNOTS... HOWEVER... EL HEIGHTS LOOK TO BE QUITE LOW AND ACTUAL SHEAR MAGNITUDE IN THE CLOUD-BEARING LAYER SHOULD BE SUBSTANTIALLY SMALLER THAN 70 KNOTS. ALSO... THERMODYNAMIC PROFILES ARE VERY WEAK... AND ALTHOUGH STRONG WIND GUSTS ALONG WITH SMALL HAIL MAY OCCUR WITH THESE TSTMS... SEVERE THREAT IS TOO LOW TO WARRENT A SLGT RISK ATTM.

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