CONVECTIVE FORECAST
VALID 14Z SUN 04/05 - 06Z MON 05/05 2003
ISSUED: 04/05 13:52Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS SW EUROPE.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS SE EUROPE.

SYNOPSIS

AMPLIFYING UPPER LONG-WAVE TROUGH OVER THE EASTERN ATLANTIC AT THE MOMENT ... WILL SLOWLY PROGRESS EAST AND REACH THE WESTERN EUROPEAN STATES BY THE END OF THIS PERIOD. THIS WILL RESULT IN A STRONG SSWLY UPPER FLOW OVER WESTERN AND CENTRAL EUROPE TOWARDS MONDAY 06Z. MAIN FRONTAL BOUNDARY AHEAD OF THE LONGWAVE TROUGH HAS REACHED W IBERIA AND THE BRITISH ISLES ... WITH A DEEPENING FRONTAL WAVE PRESENT IN THE VICINITY OF IRELAND.

DISCUSSION

...CENTRAL EUROPE ...
DEEP SOUTHERLY FLOW WILL ESTABLISH OVER SOUTHERN AND CENTRAL EUROPE AHEAD OF THE UPPER TROUGH LATE SUNDAY NIGHT. PRONOUNCED ELEVATED MIXED LAYER HAS ADVECTED NORTH AS FAR AS CENTRAL FRANCE ALREADY ... BUT LOW-LEVEL MOISTURE IS TOO SPARSE ATTM TO SUPPORT DEVELOPMENT OF CAPE DESPITE UNIMPEDED INSOLATION.

SMALL CHANCE OF TSTM DEVELOPMENT APPEARS TO EXIST OVER FRANCE LATE IN THE NIGHT AS ELEVATED MIXED LAYER SPREADS NORTH. SOME DCVA-RELATED UVM ALONG THE COLD FRONT ... AND ISENTROPIC ASCENT ASSOCIATED WITH SELY LOW-LEVEL FLOW FROM THE MEDITERRANEAN SEA ... MAY PROVE SUFFICIENT TO ALLOW A FEW TSTMS FORM ALONG AND W OF THE COLD FRONT LATE TONIGHT. INSTABILITY SHOULD BE VERY MEAGER THOUGH ... AND SEVERE POTENTIAL IS QUITE LOW.

...IBERIA ...
MODIFIED 00Z AND 12Z SOUNDINGS FROM SPAIN SUGGEST THAT WEAK CAPE MAY BE REALIZED IF CAP ASSOCIATED WITH THE EML CAN BE OVERCOME. LARGE-SCALE UVV'S ASSOCIATED WITH THE APPROACHING TROUGH WILL REMAIN WEST OF THE SPAIN THIS PERIOD ... BUT A FEW TSTMS HAVE FORMED ALONG THE SURFACE COLD FRONT OVER S SPAIN. ALTHOUGH INSTABILITY WILL BE RATHER WEAK ... DEEP-LAYER SHEAR OF 30 TO 40 KNOTS AND A DEEPLY MIXED SUBCLOUD LAYER SUGGEST SOME THREAT OF ISOLATED STRONG DOWNDRAFTS AND MAYBE SOME HAIL BRIEFLY APPROACHING SEVERE LEVELS.

...SE EUROPE...
WEAK COLD FRONT HAS REACHED THE S BALKAN STATES ... AND A FEW HIGH-BASED TSTMS HAVE INITIATED DURING THE LAST FEW HOURS. EXPECT BRIEF STRONG WIND GUSTS ALONG WITH SMALL HAIL WITH THE STRONGER CELLS. TSTMS SHOULD DIMINISH AFTER SUNDOWN GIVEN VERY WEAK UPPER SUPPORT.

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