CONVECTIVE FORECAST
VALID 06Z TUE 29/04 - 06Z WED 30/04 2003
ISSUED: 28/04 23:38Z
FORECASTER: GROENEMEIJER

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FRANCE AND SPAIN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS PARTS OF THE BRITISH ISLES THE BENELUX, GERMANY, POLAND, CZECH REPUBLIC, AUSTRIA, SWITZERLAND, ITALY, FRANCE, SPAIN AND PORTUGAL.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS PARTS OF RUSSIA, BELARUS AND THE UKRAINE.

SYNOPSIS

AN UPPER LOW IS LOCATED TO THE SOUTHWEST OF IRELAND. WITHIN A BROAD SOUTHWESTELY JET OVER WESTERN EUROPE A SUBTLE SHORTWAVE TROUGH APPROACHES THE BRITISH ISLES. OVER EXTREME EASTERN EUROPE, A WEAK UPPER TROUGH IS PRESENT.

DISCUSSION

...NORTHERN SPAIN, SOUTHERN AND EASTERN FRANCE, WESTERN ALPS...
DESPITE RELATIVELY LIMITED INSTABILITY, DEEP MOIST CONVECTION IS EXPECTED TO FORM BY LATE AFTERNOON OVER THE AREA. GIVEN HIGH /60-70 KT/ 0-6KM SHEAR SOME ROTATING UPDRAFTS /SUPERCELLS/ WILL LIKELY FORM. THERE IS A RISK OF LARGE HAIL AND STRONG WINDS WITH THESE STORMS. THE CONVECTION WILL LIKELY ORGANISE INTO LINEAR CONVECTIVE MODES DURING THE EVENING, MOVING INTO NORTHEASTERN FRANCE AS SEVERE THREAT DEMINISHES.

...BRITISH ISLES...
UNSTABLE AIR-MASS OF POLAR ORIGIN IS PRESENT OVER MUCH OF THE BRITISH ISLES. MOST INTENSE CONVECTION WILL FORM DURING THE DAY OVER LAND. PARTICULARLY OVER BRITAIN, SHEAR WILL GRADUALLY INCREASE ON APPROACH OF AN UPPER TROUGH. SOME LINEAR CONVECTIVE ELEMENTS MAY FORM. SOME SHORT-LIVED ROTATING UPDRAFTS CAN ALSO NOT BE RULED OUT. IF THESE OCCUR, THERE IS A CHANCE OF HAIL APPROACHING SEVERE LIMITS, STRONG GUSTS AND POSSIBLY A TORNADO. HOWEVER, THE RISK SEEMS TO BE TOO SMALL TO WARRANT A RISK CATEGORY.

#