CONVECTIVE FORECAST - UPDATE
VALID 15Z FRI 25/04 - 06Z SAT 26/04 2003
ISSUED: 25/04 14:52Z
FORECASTER: GROENEMEIJER

GENERAL THUNDERSTORMS ARE FORECAST ACROSS IRELAND, NORTHERN IBERIA, MUCH OF FRANCE, THE BENELUX AND WESTERN GERMANY, NORTHERN ITALY, THE EASTERN AND SOUTHERN BALKANS, THE SOUTHERN UKRAINE AND TURKEY

SYNOPSIS

AN UPPER TROUGH IS PRESENT OVER THE WESTERN UKRAINE AND WESTERN PART OF THE BLACK SEA. A LARGE UPPER RIDGE IS PRESENT OVER WESTERN EUROPE. A SOUTHWESTERLY JET IS EJECTING FROM THE EASTERN ATLANTIC INTO WESTERN EUROPE. SOUTH OF AN UPPER LOW WEST OF IRELAND. A SEPARATE VORT MAX IS LOCATED ABOUT 1000 KMS WEST OF NORTHERN IBERIA, MOVING NORTHEASTWARD. ANOTHER SHORTWAVE TROUGH IS LOCATED JUST SOUTH OF THE MAIN UPPER LOW. IT WILL LIKELY AFFECT IRELAND OVERNIGHT.

DISCUSSION

...IRELAND...
MARGINAL INSTABILITY IS EVIDENT FROM 12Z VALENTIA SOUNDING. PASSAGE OF A UPPER SHORTWAVE TROUGH WILL BE ACCOMPANIED BY A FEW STORMS, SOME OF WHICH ACCOMPANIED WITH THUNDER, ESPECIALLY IN THE WESTERN AND SOUTHERN COASTAL AREAS. STRONG LOW-LEVEL SHEAR PROFILES AND LOW LCL HEIGHTS WILL POSSIBLY ALLOW FOR A FEW WEAK SHORT-LIVED TORNADOES IN THESE AREAS. SOME SMALL HAIL AND STRONG GUSTS ARE ALSO POSSIBLE, BUT OVERALL THREAT IS TOO LOW FOR A SLIGHT RISK.

...WESTERN EUROPE...
WITHIN WARM ADVECTION REGIME OVER WESTERN EUROPE, AN AREA OF TOWERING CUMULUS OVER WESTERN FRANCE WILL LIKELY DEVELOP INTO A FEW THUNDERSTORMS DURING THE NEXT FEW HOURS. THESE STORMS WILL MOVE NORTHEAST AND AFFECT BELGIUM AND THE NETHERLANDS AND POSSIBLY PARTS OF NORTHWESTERN GERMANY OVERNIGHT. SOME MORE LOCAL STORMS ARE PRESENT OVER THE UPPER RHINE VALLEY. THESE WILL LIKELY DIE DURING THE EVENING. A FEW THUNDERSTORMS CAN ALSO NOT BE EXLUDED NEAR THE COLD FRONT OVER BRETAGNE AND NORMANDY AND FURTHER SOUTH OVER NORTHERN SPAIN. GIVEN RELATIVELY LOW INSTABILITY AND ONLY MODERATE SHEAR PROFILES AT BEST, THESE STORMS ARE NOT EXPECTED TO PRODUCE ANY SEVERE WEATHER.

...SOUTHERN AND EASTERN BALKANS AND SOUTHERN UKRAINE...
SOUTH OF AN ADVANCING COLD FRONT A MARGINALLY UNSTABLE AIR IS PRESENT OVER THE AREA IN WHICH SOME STORMS CAN FORM. SEVERE THUNDERSTORMS ARE NOT LIKELY DUE TO RELATIVELY WEAK INSTABILITY, WEAK VERTICAL WIND SHEAR AND. HOWEVER ... STORMS MAY PRODUCE SOME SMALL HAIL AND/OR NON-SEVERE WIND GUSTS.

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