VALID 12Z SUN 27/10 - 00Z MON 28/10 2002
ISSUED: 27/10 13:01Z
FORECASTER: GROENEMEIJER

THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF ENGLAND, THE BENELUX COUNTRIES, EXTREMELY NORTHERN FRANCE, MUCH OF NORTHERN AND CENTRAL GERMANY AND EXTREMELY WESTERN POLAND.
THIS IS A PARTICULARLY DANGEROUS SITUATION

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS AN AREA SURROUNDING THE HIGH RISK AREA.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS AN AREA SURROUNDING THE MODERATE RISK AREA.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS THE NORWEGIAN SEA, PARTS OF SOUTHERN SCANDINAVIA AND THE BALTIC SEA, MUCH OF NORTHWESTERN CONTINENTAL EUROPE, THE BRITISCH ISLES AND ADJACENT PARTS OF THE ATLANTIC.

SYNOPSIS

A SURFACE LOW OVER SOUTHERN NORTH SEA HAS AN EXTREMELY STRONG WIND FIELD ON ITS SOUTHERN FLANK. A COLD FRONT OVER WESTERN GERMANY IS EXPECTED TO MOVE QUICKLY EASTWARD. A TROUGH/BACK-BENT OCCLUSION IS EXPECTED TO MOVE INTO THE NORTHERN BENELUX COUNTRIES AND MOVE FURTHER EASTWARD THEREAFTER.

DISCUSSION

...NORTHWESTERN EUROPE...
LINEAR CONVECTIVE ELEMENTS HAVE FORMED ON THE REAR SIDE OF THE COLD FRONT. VERY STRONG /NEAR 50 KNOT/ 0-1 KM LOW-LEVEL WIND SHEAR WILL PROVIDE AN ENVIRONMENT FAVOURABLE FOR THE DEVELOPMENT OF HELICAL INFLOWS. THIS MEANS SOME EMBEDDED ROTATING UPDRAFTS ARE POSSIBLE AND SOME CHANCE OF TORNADOES EXISTS. IN ASSOCIATION WITH THESE UPDRAFTS SOME MARGINALLY SEVERE HAIL MAY BE POSSIBLE. MAIN THREAT HOWEVER WILL BE EXTREMELY STRONG GUSTS. GUSTS NEAR 70 KNOTS HAVE BEEN OBSERVED NOT ASSOCIATED WITH CONVECTIVE ACTIVITY. STRAIGHT-LINE WIND GUSTS ENHANCED BY CONVECTION WILL LIKELY BE AS HIGH AS 80-90 KNOTS...ESPECIALLY IN ASSOCIATION WITH CONVECTION NEAR TROUGH/BACK-BENT OCCLUSION WHERE PRESSURE GRADIENT IS MAXIMAL.

GREATEST THREAT WILL BE IN ENGLAND AROUND THE TIME OF ISSUANCE OF THIS OUTLOOK...IN THE BENELUX/FRANCE IN THE SECOND HALF OF THE AFTERNOON...IN GERMANY IN THE EVENING...AND POLAND NEAR MIDNIGHT.

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