DAY 2 CONVECTIVE OUTLOOK
VALID 06Z SAT 21/12 - 06Z SUN 22/12 2002
ISSUED: 20/12 19:47Z
FORECASTER: GATZEN

SYNOPSIS

LARGE AND INTENSE EASTERN EUROPEAN TROUGH STILL AMPLIFIES WITHIN THE FORECAST PERIODE ... EMENATING FROM NORTHERN ATLANTIC LONG-WAVE TROUGH INTENSE SHORT-WAVE TROUGH IS FORECASTED TO MIGRATE NORTHEASTWARD. ADVECTION OF WARM AND MOIST SUBTROPICAL AIR WILL AFFECT EXTREMELY WESTERN FORECAST AREA. AT THE SURFACE ... IN THE RANGE OF WARM ADVECTION STRONG SURFACE LOW IS PROGGED TO REACH WESTERN GREAT BRITAIN AT THE END OF THE FORECAST PERIOD.

DISCUSSION

...WESTERN EUROPE ...
FOCUS OF THUNDERSTORM DEVELOPMENT SHOULD BE THE SHORT-WAVE TROUGH MENTIONED ABOVE. MODERATE ENERGETIC SUBTROPICAL AIRMASS WITH 850 HPA-THETA-E ABOVE 40 C IS ADVECTED UP TO SOUTHERN GREAT BRITAIN. STRONGEST THETA-E-ADVECTION SHOULD DOMINATE ALONG FRONTAL BOUNDARY OVER WESTERN NORTH SEA, WHERE COLD POLAR AIRMASS IS FORECASTED TO BE REPLACED EASTWARD. AT THE SAME TIME, SLIGHT VORTICITY-ADVECTION SHOULD AFFECT THE AREA. ALTHOUGH CHANCE OF THUNDERSTORMS SHOULD BE VERY LIMITED, SOME ELEVATED THUNDERSTORMS ARE EXPECTED ... HOWEVER ... EVEN AS FORECASTED SHEAR-PROFILES SEEM TO BE FAVOURABLE FOR HIGH VALUES OF HELICITY, EXPECTED THUNDERSTORMS SHOULD BE TOO WEAK TO ROOT DOWN TO THE BOUNDARY-LAYER. FURTHERMORE, BOUNDARY AIRMASS IS EXPECTED TO BE TOO COLD TO ASSIST THUNDERSTORM DEVELOPMENT.

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