DAY 1 CONVECTIVE OUTLOOK
VALID 14Z SUN 30/03 - 06Z MON 31/03 2003
ISSUED: 30/03 14:14Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS CENTRAL AND EASTERN EUROPE.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE WESTERN MEDITERRANEAN SEA.

SYNOPSIS

VIGOROUS UPPER TROUGH ATTM OVER S SCANDINAVIA ... WILL CONTINUE TO DIG SOUTH ... AND WILL SWEEP ACROSS S SWEDEN ... POLAND AND THE BATIC STATES DURING THE EVENING/NIGHT. THIS FEATURE WILL PHASE WITH WEAK UPPER LOW OVER THE IBERIAN PENINSULA ... WHICH WILL ACCELERATE EAST TO BE CENTERED OVER THE WESTERN MEDITERRANEAN SEA TOWARDS THE END OF THIS FORECAST PERIOD. AT LOW LEVELS ... MARGINALLY UNSTABLE MODIFIED SUBTROPICAL AIRMASS IS RESIDING OVER PARTS OF CENTRAL EUROPE. SHALLOW COOL/DRY AIRMASS IS CURRENTLY INVADING NORTHERN GERMANY ... NORTHERN POLAND AND THE BENELUX STATES IN ADVANCE OF THE MAIN COLD FRONT ASSOCIATED WITH THE DIGGING UPPER TROUGH.

DISCUSSION

...GERMANY ... FRANCE...
NUMEROUS SHOWERS AND THUNDERSTORMS HAVE FORMED IN WEAKLY CAPPED MARGINALLY UNSTABLE AIRMASS OVER CENTRAL EUROPE. THOUGH LACK OF LOW-LEVEL FORCING FOR UPWARD MOTION SUGGESTS THAT TSTMS SHOULD DIMINISH WITH THE LOSS OF DAYTIME HEATING ... SHALLOW COLD FRONT ATTM OVER NORTH GERMANY/BENELUX MAY HELP MAINTAINING SOME TSTMS LATER TONIGHT AS IT ENCOUNTERS MARGINALLY UNSTABLE AIRMASS OVER S GERMANY AND FRANCE. ALTHOUGH LARGE-SCALE KINEMATIC AND THERMODYNAMIC ENVIRONMENT DOES NOT FAVOR EVOLUTION OF SEVERE THUNDERSTORMS ... INTERACTION OF THE CELLS WITH OUTFLOW BOUNDARIES MAY PROMOTE BRIEF UPDRAFT ROTATION ... SUGGESTING A SLIGHTLY ENHANCED THREAT OF MARGINALLY SEVERE HAIL ... BUT ALLOVER THREAT IS TOO LOW TO WARRANT A SLGT RISK.

...EASTERN EUROPE...
PLUME OF MARGINALLY UNSTABLE AIRMASS IS EXPECTED TO EXTEND ACROSS EAST POLAND INTO THE EASTERN BALTIC STATES AHEAD OF THE COLD FRONT LATER TONIGHT. MAIN PROBLEM LOOKS TO BE THE POSITION OF DCVA-RELATED ASCENT ... WHICH WILL BE WELL NE OF THE MAIN SURFACE COLD FRONT. ALSO ... SHALLOW COOL AIRMASS AHEAD OF THE MAIN COLD FRONT SHOULD STABILIZE PREFRONTAL ENVIRONMENT. CURRENT THINKING IS THAT BEST CHANCES FOR DEEP CONVECTION WILL EXIST AT THE NORTHERN PORTIONS OF THE THETA-E PLUME OVER THE BALTIC STATES WHERE UVV'S WILL BE SOMEWHAT STRONGER CLOSE TO THE FRONT THAN FARTHER S. IF DEEP CONVECTION INDEED FORMS ... IT WILL BENEFIT FROM QUITE STRONG DEEP-LAYER SHEAR. ALSO ... GFS FIELDS INDICATE SRH VALUES AT OR ABOVE 150 M2/S2 ... ALTOGETHER SIGNALLING THREAT OF SUPERCELLS AND BOW ECHOES WITH PRIMARY THREATS BEING STRONG/DAMAGING WIND GUSTS ... MARGINALLY SEVERE HAIL AND MAYBE A BREIF TORNADO. GIVEN RATHER LOW CONFIDENCE THAT THUNDERSTORMS FORM ... A SLGT RISK IS NOT NECESSARY AT THE MOMENT.

A FEW WEAK TSTMS HAVE FORMED AHEAD OF AND BENEATH WEAK UPPER LOW OVER EASTERN EUROPE ... THESE STORMS WILL LIKELY REMAIN SUB-SEVERE ... AND SHOULD ALSO DIMINISH TOWARDS LATE SUNDAY EVENING.

...WESTERN MEDITERRANEAN...
BENEATH UPPER COLD POOL ASSOCIATED WITH THE MEDITERRANEAN UPPER LOW ... A FEW THUNDERSTORMS SHOULD DEVELOP TONIGHT AS THE LOW ENCOUNTERS THE WESTERN MEDITERRANEAN SEA. ORGANIZED SEVERE STORMS ARE QUITE UNLIKELY THOUGH GIVEN POOR KINEMATIC AND THERMODYNAMIC PROFILES.

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