CONVECTIVE FORECAST - UPDATE
VALID 18Z THU 03/04 - 06Z FRI 04/04 2003
ISSUED: 03/04 17:58Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS NORWAY.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE WESTERN MEDITERRANEAN SEA.

SYNOPSIS

DISCUSSION

...NE GERMANY ... W POLAND...
DRY AIRMASS IN THE LEE OF THE SCANDINAVIAN MOUNTAINS HAS BEEN ADVECTED SOUTH MORE SLOWLY THAN ANTICIPATED ... WHICH HAS RESULTED IN ANOTHER ROUND OF NUMEROUS SHOWERS AND THUNDERSTORMS OVER NE GERMANY AND WEST POLAND. DEEPEST CONVECTION IS PRESENTLY OCCURRING BENEATH BAND OF DCVA WHICH IS EXPECTED TO SHIFT EAST WITH THE UPPER TROUGH. ALTHOUGH RAIN AND GRAUPEL SHOWERS WILL LIKELY CONTINUE OVER THE NEXT FEW HOURS ... ACTIVITY HAS WEAKENED ALREADY WITH THE LOSS OF DAYTIME HEATING ... AND A GEN THUNDER AREA IS NO LONGER NECESSARY.

...MEDITERRANEAN...
COMPLEX SCENARIO HAS DEVELOPED OVER THE MEDITERRANEAN REGIONS ... PRIMARY FEATURE IS A DEEP AND QUITE INTENSE UPPER CUT-OFF LOW WHICH IS ROTATING AROUND THE PERIPHERY OF THE MAIN UPPER LONG-WAVE TROUGH. INTENSE SOUTHWARD PROPAGATING 300 HPA JET STREAK ATTM OVER THE WEST MEDITERRANEAN SEA WILL CROSS THE S MEDITERRANEAN ... N TUNESIA AND ALGERIA DURING THE NIGHT ... AND AFFECT THE SOUTHEASTERN PORTIONS FORECAST AREA ON FRIDAY.

MODEL FIELDS AS WELL AS LATEST SOUNDINGS OVER THE NW MEDITERRANEAN INDICATE MID-LEVEL MOISTURE SPREADING W/SW N OF THE SFC LOW CENTER ... WITH TSTMS PRESENTLY OCCURRING AHEAD OF FAIRLY SMALL AND INTENSE VORT MAX OVER THE W MEDITERRANEAN SEA ... THIS DEVELOPMENT ALSO HAPPENS TO COINCIDE WITH THE NOSE OF 850 HPA THETA-E PLUME ... ALTOGETHER SUGGESTING THAT TSTMS ARE SLIGHTLY ELEVATED. HOWEVER ... IR SATELLITE IMAGERY INDICATES THAT CLOUD TOPS ARE RATHER WARM ... AND TSTMS MAY ALSO HAVE FORMED IN COOL/MOIST SFC-BASED MIXED LAYER. IN EITHER CASE ... TSTMS SHOULD CONTINUE DURING THE NIGHT AHEAD OF THIS VORT MAX. THREAT OF ORGANIZED SEVERE IS RATHER LOW GIVEN WEAK THERMODYNAMIC AND KINEMATIC PARAMETERS.

...NORWAY...
VIGOROUS SHORT-WAVE TROUGH ATTM E OF ICELAND IS RAPIDLY MOVING EAST ... AND IN THE WAKE OF THE ASSOCIATED COLD FRONT ... RELATIVELY DEEP CONVECTIVE MIXING WILL LIKELY OCCUR. STRONG OROGRAPHIC FORCING AT THE NORWEGIAN W COAST SHOULD PROMOTE A FEW LIGHTNING STRIKES TOWARDS EARLY FRIDAY MORNING. THOUGH SFC WINDS WILL LIKELY EXCEED 50 KT IN ASSOCIATION WITH THE STRONG GRADIENT FLOW ... CONVECTIVE TRANSPORT OF HIGH HORIZONTAL MOMENTUM TO THE SURFACE IS EXPECTED TO AUGMENT SEVERE WIND GUSTS LOCALLY.

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