VALID 06Z SAT 23/11 - 06Z SUN 24/11 2002
ISSUED: 23/11 03:10Z
FORECASTER: GROENEMEIJER

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EXTREME SOUTHERN PORTUGAL AND EXTREME SOUTHERN SPAIN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS

SYNOPSIS

AN UPPER LOW IS LOCATED WEST OF IRELAND. A TROUGH FROM THE LOW SOUTHWARD IS EXPECTED TO AMPLIFY SOMEWHAT AND PROGRESS EASTWARD REACHING THE WESTERN IBERIAN PENINSULA BY THE END OF THE PERIOD. AIR-MASS IN A WIDE AREA AROUND THE LOW IS NEUTRAL OR SLIGHTLY UNSTABLE SO THAT WIDESPREAD CONVECTIVE OVERTURNING OCCURS. SOME CONVECTION IS LOCALLY CLUSTERED NEAR SURFACE TROUGHS.

DISCUSSION

...EXTREME SOUTHERN PORTUGAL AND EXTREME SOUTHERN SPAIN...
NUMERICAL MODELS AGREE ON DEVELOPING A TWO BAROCLINIC WAVES INV OF IBERIAN PENINSULA DURING THE PERIOD. ONE WILL BE LOCATED OVER NORTHEASTERN SPAIN AND WILL ONLY WEAKLY AMPLIFY. A SECOND WAVE WILL DEVELOP JUST WEST OF SOUTHERN PORTUGAL. THAT WAVE IS EXPECTED TO BE LOCATED OVER THE SOUTHWESTERN IBERIAN PENINSULA AT THE END OF THE PERIOD. A STRONG WIND FIELD IS EXPECTED TO DEVELOP ALONG ITS SOUTHERN FLANK. GIVEN SLIGHTLY UNSTABLE AND UNCAPPED ATMOSPHERE WIDESPREAD CONVECTIVE ACTIVITY IS EXPECTED TO OCCUR INV OF THE WAVE. DEVELOPMENT OF A LINEAR MCS ALONG COLD FRONT ASSOCIATED WITH THE WAVE SEEMS LIKELY. GIVEN STRONG /NEARLY UNIDIRECTIONAL/ SHEAR VALUES STRONG GUSTS WILL BE THE MAIN THREAT. SOME SMALL HAIL IS ALSO POSSIBLE. SOME STORMS WITH MARGINALLY SEVERE GUSTS MAY OCCUR BEHIND THE COLD FRONT. ELSEWHERE STORMS ARE NOT EXPECTED TO BE SEVERE.

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