CONVECTIVE FORECAST
VALID 06Z SAT 21/06 - 06Z SUN 22/06 2003
ISSUED: 20/06 19:52Z
FORECASTER: DAHL

GENERAL THUNDERSTORMS ARE FORECAST ACROSS SOUTHERN ... WESTERN ... AND WEST-CENTRAL EUROPE.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS EASTERN EUROPE.

SYNOPSIS

INTENSE SHORT-WAVE TROUGH ATTM OVER N GERMANY AND POLAND WILL CONTINUE TO DIG SE ... REACHING THE NORTHERN BLACK SEA TOWARDS THE END OF THE FCST PERIOD. AS THE UPPER TROUGH ATTM OVER THE CENTRAL ATLANTIC PROGRESSES EASTWARD ... DOWNSTREAM UPPER RIDGE ATTM W OF THE BRITISH ISLES WILL AMPLIFY ... AND IS EXPECTED TO COVER THE WESTERN PARTS OF CENTRAL EUROPE BY SUNDAY 06 Z. AT LOW LEVELS ... WARM AIRMASS OVER IBERIA AND S FRANCE WILL BE ADVECTED NORTH ... WITH THE ASSOCIATED WARM-FRONTAL BOUNDARY EXPECTED TO STRETCH FROM CENTRAL GREAT BRITAIN TO SWITZERLAND BY SUNDAY 06 Z. DEEP POLAR AIRMASS WILL CONTINUE TO AFFECT MUCH OF NORTHERN AND EASTERN EUROPE.

DISCUSSION

...FRANCE...
PRONOUNCED ELEVATED MIXED LAYER ... ATTM COVERING MUCH OF THE IBERIAN PENINSULA ... IS EXPECTED TO BE ADVECTED INTO S FRANCE AND THE GULF OF BISCAY ... MAYBE AS FAR NORTH AS S GREAT BRITAIN LATE IN THE PERIOD. PRIMARY CONCERN WILL BE LACK OF LOW-LEVEL MOISTURE ... WITH MIXED-LAYER DEWPOINTS EXPECTED TO BE ONLY IN THE 12 TO 14 °C RANGE. INDICATIONS ARE THAT THIS WILL SUPPORT A FEW HUNDRED J/KG AFTERNOON CAPE ... BUT THAT THE BOUNDARY-LAYER AIRMASS WILL BE THOROUGHLY CAPPED. ANOTHER PROBLEM WILL BE LACK OF LARGE-SCALE UPWARD VERTICAL MOTION DURING THE DAY ... SUGGESTING THAT ANY DEEP CONVECTION THAT FORMS WILL BE VERY ISOLATED. PRIND THAT A FEW OROGRAPHICALLY FORCED TSTMS MAY FORM ACROSS S FRANCE LATE IN THE DAY ... BUT VERY WEAK WIND SHEAR SHOULD LIMIT THREAT OF ORGANIZED SEVERE TSTMS. A FEW STRONG WIND GUSTS AND SMALL HAIL SHOULD BE EXPECTED THOUGH. LATE IN THE NIGHT/EARLY MORNING ... ELEVATED TSTMS MAY FORM ALONG AND N OF THE WARM FRONT OVER CENTRAL AND NORTHERN FRANCE. DEGREE OF ELEVATED INSTABILITY SHOULD BE QUITE MEAGER ... BUT RATHER DRY ENVIRONMENT/STEEP LAPSE RATES MAY PROMOTE ISOLATED STRONG DOWNDRAFTS. HOWEVER ... ELEVATED NATURE OF THE STORMS SHOULD KEEP SEVERE-WIND THREAT MINIMAL.

...E EUROPE...
IN THE DEEP POLAR AIR ASSOCIATED WITH THE NE EUROPEAN DIGGING TROUGH ... NUMEROUS SHOWERS AND TSTMS ARE EXPECTED TO DEVELOP WITH DAYTIME HEATING. EXPECT VERY GUSTY WINDS AND SMALL HAIL WITH THE STRONGEST CELLS ... ESPECIALLY OVER ROMANIA AND S UKRAINE WHERE DEEP-LAYER SHEAR OF ABOUT 60 KNOTS IS EXPECTED.

OTHERWISE ... WEAK SHEAR AND WEAK INSTABILITY SUGGEST NEGLIGIBLE THREAT OF ORGANIZED SEVERE STORMS.

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