VALID 14Z WED 16/10 - 00Z THU 17/10 2002
ISSUED: 16/10 14:36 Z
FORECASTER: GROENEMEIJER

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL AND NORTHEASTERN FRANCE...SOUTHWESTERN AND CENTRAL GERMANY

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE UNITED KINGDOM...THE BENELUX COUNTRIES...GERMANY...FRANCE...AND NORTHERN IBERIAN PENINSULA

SYNOPSIS

AN INTENSE /120 KT @ 250 HPA/ SOUTHWESTERLY UPPER JET IS PRESENT OVER WESTERN EUROPE. AN OLD SURFACE CYCLONE IS PRESENT JUST NORTHWEST OF THE NETHERLANDS. A FRONTAL ZONE STRETCHES FROM THE CYCLONE CENTER OVER THE CHANNEL REGION TO THE BAY OF BISCAY. AHEAD OF THE FRONTAL ZONE SOME WARM ADVECTION IS TAKING PLACE.AN UPPER VORTICITY MAXIMUM OVER WESTERN FRANCE IS EXPECTED TO TRACK QUICKLY EASTWARD THIS AFTERNOON AND EVENING.

DISCUSSION

...CENTRAL AND NORTHEASTERN FRANCE...SOUTHWESTERN AND CENTRAL GERMANY...
SOME INSOLATION AND WARM ADVECTION OVER EASTERN FRANCE HAS ENABLED TEMPERATURES TO RISE TO 22-24 DEGREES C. DEWPOINTS HAVE RISEN TO 14 - 17 C CREATING SOME LATENT INSTABILITY IN COMBINATION WITH COOLING UPPER-LEVEL TEMPERATURES. PRESENCE OF VERY HIGH LOW-LEVEL WIND SHEAR /850 HPA SPEED OF 45 - 55 KTS/ AND LIFT PROVIDED BY RISING MOTION AHEAD OF VORTICITY MAXIMUM WILL LIKELY INDUCE DEVELOPMENT OF A LINEAR CONVECTIVE MODE(S)/SQUALL-LINE(S). MAIN THREAT WITH THIS SYSTEM WILL BE SEVERE WIND GUSTS OF UP TO 70 KNOTS. GIVEN AMOUNT OF LOW-LEVEL SHEAR UPDRAFT ROTATIONS MAY FORM AND SO THAT A FEW TORNADOES ARE POSSIBLE. SITUATION MAY REQUIRE AN UPGRADE TO MODERATE RISK IF SQUALL-LINE BECOMES WELL DEVELOPED.

...BENELUX AND NORTHWESTERN GERMANY...
INSTABILITY SEEMS SIGNIFICANTLY LOWER AND ELEVATED NORTH OF NORTHERNMOST EDGE/WARM FRONT OVER BELGIUM/CENTRAL GERMANY. STRONG RISING MOTIONS WILL HOWEVER AFFECT THIS AREA AS WELL AS VORT MAX WILL ENTER THE REGION THIS EVENING. SOME CONVECTIVE DEVELOPMENT WILL HOWEVER PROBABLY TAKE PLACE AND GIVEN HIGH WIND SHEAR, NEAR SEVERE OR SEVERE GUST ARE ALSO POSSIBLE HERE. CHANCES ARE TOO SMALL THOUGH TO WARRANT A SLIGHT RISK.

...SOUTHWESTERN FRANCE...
AREA OF STRONGEST RISING MOTION HAS PASSED. HOWEVER WIND SHEAR AND INSTABILITY ARE SUCH THAT DEEP CONVECTION/THUNDERSTORMS WILL KEEP DEVELOPING. SEVERE THREAT IS RATHER LOW.

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