DAY 1 CONVECTIVE OUTLOOK
VALID 19Z WED 01/01 - 06Z THU 02/01 2003
ISSUED: 01/01 19:13Z
FORECASTER: GROENEMEIJER

GENERAL THUNDERSTORMS ARE FORECAST ACROSS PARTS OF WESTERN EUROPE AND THE CENTRAL AND EASTERN PARTS OF THE MEDITERRANEAN

SYNOPSIS

A W TO WSW POLAR JET STREAM IS BLOWING INTO WESTERN/CENTRAL EUROPE ALONG AN AXIS NEAR THE ENGLISH CHANNEL. VARIOUS VORT MAXES ARE EMBEDDED WITHIN THE JET. THE AIR-MASS NORTH OF THE SURFACE FRONT ASSOCIATED WITH THE JET IS DRY COLD AND STABLE, WHILE SOUTH OF THE FRONT MILD AND MOIST AIR IS PRESENT.

DISCUSSION

...SOUTHEASTERN BENELUX, NORTHEASTERN FRANCE, WEST-CENTRAL GERMANY....
A VORT MAX EMBEDDED IN THE JET IS PRESENT NEAR WESTERN NETHERLANDS AT 18Z. A WARM FRONT IS PRESENT ALONG A LINE FROM DUBLIN TO NEWCASTLE TO HANNOVER TO DRESDEN. SOUTH OF THE FRONT THE AIR IS MILD AND MOIST WITH HIGH DEW POINTS OF 12C MEASURED AS FAR NORTH AS PARIS. THE AIR IS NEUTRAL FOR SATURATED PARCELS OR MARGINALLY UNSTABLE / 12Z SOUNDINGS FROM BORDEAUX LFBD AND BREST LFRB SHOW AROUNG 400 J/KG OF CAPE. FURTHER NORTH SBCAPES ARE LOWER, BUT SOME ELEVATED INSTABILITY MAY BE PRESENT. LIFT ASSOCIATED WITH APPROACHIN VORT MAX HAS FACILITATED THE DEVELOPMENT OF SOME THUNDERSTORMS THE BELGIAN/ FRENCH BORDER. GIVEN STRONG SHEAR PROFILES SOME HIGH /POSSIBLY MARGINALLY SEVERE/ WIND GUSTS ARE POSSIBLE WITH THESE STORMS. THIS ACTIVITY WILL LIKELY TRACK EASTWARD AND AFFECT PARTS OF CENTRAL GERMANY LATER TONIGHT. OTHER STORMS OVER THE SOUTHERN BENELUX COUNTRIES MAY ALSO DEVELOP SOME THUNDERY ACTIVITY AND MARGINALLY SEVERE GUSTS. HOWEVER, GIVEN LOW INSTABILITY WE REFRAIN FROM ISSUING A CATEGORICAL RISK.

...WESTERN FRANCE, SOUTHERN BRITISH ISLES AND NORTHERN SPAIN...
AT THE BEGINNING OF THE FORECAST PERIOD SOME THUNDERSTORM ACTIVITY IS ONGOING OVER SOUTHWESTERN FRANCE AND NORTHERN SPAIN. THE FORMER IS ASSOCIATED WITH A WEAK UPPER TROUGH, THE LATTER ALSO WITH OROGRAPHICAL FORCING. GIVEN LESS IMPRESSIVE SHEAR VALUES THIS ACTIVITY IS NOT EXPECTED TO BE SEVERE. MORE THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF A NEW VORT MAX COMING OFF THE ATLANTIC OCEAN. A STRONG /80KT @ 500 HPA/ JET-STREAK IS PRESENT ON ITS SOUTHERN FLANK. THIS ACTIVITY MAY AFFECT EXTREME WESTERN FRANCE AND CORNWALL WITHIN THIS PERIOD. SOME SEVERE WIND GUSTS AND SMALL HAIL ARE POSSIBLE WITH THIS ACTIVITY. BECAUSE MAIN THREAT FROM THIS ACTIVITY WILL NOT AFFECT THE FORECAST AREA WITHIN THIS FORECAST PERIOD NO CATEGORICAL RISK IS ISSUED.

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