VALID 17Z TUE 12/11 - 06Z WED 13/11 2002
ISSUED: 12/11 16:48Z
FORECASTER: GATZEN

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN IBERIAN PENINSULA

GENERAL THUNDERSTORMS ARE FORECAST ACROSS WESTERN EUROPE

GENERAL THUNDERSTORMS ARE FORECAST ACROSS NORTHWESTERN MEDITERRANEAN

SYNOPSIS

NORTHEASTERN ATLANTIC TROUGH IS FORECASTED TO PROPAGATE SOUTHEASTWARD IN COMBINATION WITH STRONG AMPLIFICATION. IT WILL REACH THE IBERIAN PENINSULA TODAY. SIMULATANEOUSLY, UPPER RIDGE BUILDS UP OVER EASTERN EUROPE. AS A CONSEQUENCE, SSWLY CURRENT WILL AFFECT NEARLY COMPLETE EUROPE. THE WELL-DEFINED FRONTAL BOUNDARY FROM SWERN TO NERN EUROPE WILL TRAVEL EASTWARD SLOWLY, PRODUCING VARIOUS FRONTAL WAVES. WITHIN THE ALPS, STRONG FOEHN IS EXPECTED.

DISCUSSION

...NORTHWESTERN MEDITERRANEAN...
METEOSAT-IR SHOWS COMMA-CLOUDS WEST OF IBERIAN PENINSULA. WITHIN SOUTWESTERLY FLOW ... LINKED VORT-MAXIMA WILL PROPAGATE NORTHEASTWARD AND COMBINED CONVECTION SHOULD SPREAD TO NORTHWESTERN MEDITERRANEAN. ALTHOUGH TEMPS DOES NOT SHOW CAPE, THEY ARE NOT VERY STABLE. WITHIN THE NIGHT ... SOME THUNDERSTORMS SHOULD OCCUR. MOSTLY LINEAR SHEAR WILL NOT SUPPORT ROTATING UPDRAFTS. SEVERE POTENTIAL IS EXPECTED TO BE SMALL.

...WESTERN EUROPE...
ADDITIONAL THUNDERSTORMS HAVE FORMED OVER THE NORTH SEA AND OVER THE EASTERN ATLANTIC. WHILE NORTHERN CONVETIVE ACTIVITY SHOULD WEAKEN WITHIN THE NEXT HOURS, NEW STRONG VORT-MAXIMA OVER THE ATLANTIC WILL REACH IBERIAN PENINSULA TOMORROW MORNING. TEMPS SHOW MOIST-ADIABATIC LAPSE-RATES AND CAPE-VALUES ABOUT 100 J/KG. STRONG SUBSYNOPTIC LIFTING SHOULD LEAD TO ORGANISED THUNDERSTORM-LINES/ COMMA CLOUDS, AND COMBINED CONVECTION SHOULD BE ABLE TO REACH SEVERE LEVEL IN CONSIDERATION TO STRONG DIRECTIONAL WIND-SHEAR. WIND GUSTS UP TO 50 KN SHOULD BE THE MAIN SEVERE THREAT.

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