Day 1 Convective Outlook
 


VALID 00Z WED 04/12 - 12Z WED 04/12 2002
ISSUED: 03/12 23:52Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS MUCH OF THE MEDITERRANEAN SEA.

SYNOPSIS

EXTENSIVE UPPER LOW COVERING THE WESTERN AND CENTRAL MEDITERRANEAN REGIONS WILL SLOWLY SPREAD SE DURING THE FCST PERIOD. INTENSE NRN STREAM TROUGH ATTM OVER THE N ATLANTIC...WILL RAPIDLY DIG SOUTHEASTWARDS AND IS EXPECTED TO REACH THE BRITISH ISLES ON WEDNESDAY MORNING. AT LOW LEVELS... LARGE ANTICYCLONE COVERING NERN PARTS OF EUROPE AS WELL AS RUSSIA... IS ADVECTING SEASONABLY COLD/DRY AIR INTO NERN PARTS OF THE FCST AREA. SFC LOW ASSOCIATED WITH THE MEDITERRANEAN UPPER LOW... IS EXPECTED TO DEEPEN SOMEWHAT AHEAD OF APPROACHING VORT MAX ROTATING ABOUT THE PERIPHERY OF THE MAIN TROUGH... TRAILING COLD FRONT ATTM CURVING ACROSS THE S-CNTRL MEDITERRANEAN SEA INTO CNTRL ITALY...IS PROGGED TO REACH THE ERN ADRIATIC SEA TOWARDS THE END OF THE FCST PERIOD.

DISCUSSION

...S-CNTRL INTO ERN MEDITERRANEAN...
TSTMS HAVE DEVELOPED ALONG THE COLD FRONT OVER THE ADRIATIC SEA AND THE S-CNTRL MEDITERRANEAN SEA AHEAD OF UPPER VORT MAX... AS WELL AS FARTHER E IN LOW-LEVEL WAA REGIME AT ERN EDGE OF 850 HPA THETA-E PLUME STRETCHING NORTHWARDS AHEAD OF THE COLD FRONT. MODELS INDICATE STRENGTHENING DYNAMIC FORCING FOR UPWARD VERTICAL MOTION OVER THE NEXT HOURS... WHICH SHOULD INCREASE TSTM COVERAGE DURING THE NIGHT. AVAILABLE SOUNDINGS DO NOT SAMPLE AIRMASS IN THE NARROW WARM SECTOR E OF THE COLD FRONT... BUT CAPES SHOULD HARDLY EXCEED 500 J/KG. AS SHEAR IS INCREASING OVER THIS REGION LATER TONIGHT... A FEW MARGINALLY SEVERE WIND GUSTS AS WELL AS SMALL HAIL MAY OCCUR WITH THE STRONGEST CELLS. ALTOGETHER... KINEMATIC AND THERMODYNAMIC FIELDS APPEAR TO BE TOO WEAK THOUGH FOR A SIGNIFICANT SEVERE TSTM THREAT.

...W MEDITERRANEAN...
TSTMS HAVE ALSO FORMED IN THE POSTFRONTAL ENVIRONMENT IN DEEP POLAR AIRMASS INVOF UPPER THERMAL TROUGH. THERMODYNAMIC AS WELL AS SHEAR PROFILES DO NOT SUGGEST MUCH OF A SEVERE THREAT ALTHOUGH LOW WBZ HEIGHTS MAY SUPPORT ISOLATED HAIL APPROACHING SEVERE LEVELS.

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