VALID 00Z SUN 27/10 - 00Z MON 28/10 2002
ISSUED: 26/10 20:15Z
FORECASTER: GROENEMEIJER

THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN IRELAND, MUCH OF ENGLAND, THE BENELUX COUNTRIES, MUCH OF NORTHERN AND CENTRAL GERMANY

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 MUCH OF THE NORWEGIAN SEA, SOUTHERN SCANDINAVIA, MUCH OF NORTHWESTERN CONTINENTAL EUROPE, THE BRITISH ISLES AND ADJACENT PARTS OF THE ATLANTIC OCEAN.

SYNOPSIS

...A PARTICULARLY DANGEROUS SITUATION IS FORECAST...

A STRONG ZONAL JET IS PRESENT OVER THE EASTERN ATLANTIC. A STRONG SURFACE CYCLONE NOW LOCATED ABOUT 600 KM WEST OF THE SOUTHWESTERN TIP OF IRELAND IS EXPECTED TO MOVE EASTWARD. A VERY STRONG CYCLONIC WIND FIELD HAS FORMED AROUND THE SYSTEM. SOME INSTABILITY IS BUILDING IN THE POLAR AIR MASS WEST OF THE COLD FRONT ASSOCIATED WITH THE SYSTEM.

DISCUSSION

...SOUTHERN IRELAND, MUCH OF ENGLAND, THE BENELUX COUNTRIES, MUCH OF NORTHERN AND CENTRAL GERMANY...
AFOREMENTIOND INTENSE LOW LEVEL SYSTEM IS EXPECTED TO FOLLOW AN EASTERLY TO EASTNORTHEASTERLY TRACK. LATEST MODEL RUNS AGREE QUITE WELL ON DEVELOPMENT AND MOVEMENT OF THE CYCLONE. THE HIGHEST GUSTS WILL LIKELY BE ASSOCIATED WITH A POST COLD-FRONTAL TROUGH/BACK-BENT OCCLUSION...THAT WILL AFFECT SOUTHERN ENGLAND FROM 3Z TILL TOMORROW NOON AND THE BENELUX COUNTRIES FROM EARLY AFTERNOON TILL EARLY EVENING AND GERMANY AFTER 16Z.

CURRENTLY...MAXIMUM SUSTAINED WINDS ARE NEAR 60 KTS PER SCATTEROMETER ESTIMATES. WIND FIELD WILL REMAIN AT LEAST THIS STRONG DURING THE NEXT 24 HOURS. VERY HIGH SHEAR VALUES AND LINEAR FORCING WILL LIKELY INDUCE LINEAR CONVECTIVE DEVELOPMENT ALONG TROUGH/BENT-BACK OCCLUSION. STRONG /50 KNOT/ 0-1 KM LOW-LEVEL WIND SHEAR WILL PROVIDE AN ENVIRONMENT FAVOURABLE FOR THE DEVELOPMENT OF HELICAL INFLOWS NEAR CONVECTIVELY OR OROGRAPHICALLY INDUCED FLOW PERTURBATIONS. THIS MEANS SOME EMBEDDED ROTATION UPDRAFTS ARE POSSIBLE AND SOME CHANCE OF TORNADOES EXISTS. IN ASSOCIATION WITH THESE SOME MARGINALLY SEVERE HAIL MAY BE POSSIBLE. MAIN THREAT HOWEVER WILL BE EXTREMELY STRONG GUSTS. BASED ON FORECAST 850 MB WINDS OF 70-80 KTS AND EFFECTS OF CONVECTIVE DEVELOPMENT, HIGHEST STRAIGHT-LINE WIND GUSTS WILL LIKELY BE AS HIGH AS 80-90 KNOTS.

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