CONVECTIVE FORECAST
VALID 06Z MON 02/06 - 06Z TUE 03/06 2003
ISSUED: 01/06 23:41Z
FORECASTER: GROENEMEIJER

GENERAL THUNDERSTORMS ARE FORECAST ACROSS MUCH OF WESTERN, CENTRAL AND SOUTH-CENTRAL EUROPE AS WELL AS MUCH OF TURKEY AND A PART OF RUSSIA.

SYNOPSIS

MAIN FEATURES ARE A LARGE UPPER LOW IS SITUATED WEST OF THE BRITISH ISLES, A RIDGE OVER WESTERN SCANDINAVIA AND A TROUGH OVER NORTHWESTERN RUSSIA. QUIESCENT CONDITIONS ARE PRESENT OVER THE MEDITERRANEAN AREA.

DISCUSSION

...BENELUX, WESTERN GERMANY, EASTERN FRANCE...
AT THE BEGINNING OF THE FORECAST PERIOS A VORT MAX/SHORTWAVE TROUGH WILL BE LOCATED ON THE SOUTHEASTERN FLANK OF THE ATLANTIC UPPER LOW FROM SW IRELAND TO CENTRAL FRANCE. A SURFACE TROUGH/CONVERGENCE LINE IS LOCATED AHEAD OF THE UPPER TROUGH ALONG THE ENGLISH EAST COAST OVER BELGIUM INTO EASTERN FRANCE. THE LINE IS EXPECTED TO MOVE SLOWLY NORTHEASTWARD, REACHING A LINE FROM BREMEN TO NEAR NEURENBERG BY TUESDAY 06Z. SOME THUNDERSTORMS WILL LIKELY BE ONGOING NEAR THE CONVERGENCE LINE AT THE BEGINNING OF THE PERIOD. AS DAYTIME HEATING COMMENCES, CONVECTIVE ACTIVITY WILL REINTENSIFY. EXPECT MULTIPLE MCSS TO FORM AND MOVE NORTHWARD ALONG THE CONVERGENCE LINE DURING THE DAY AND OVERNIGHT. GFS PRODUCES 2000 J/KG 30HPA MLCAPE, BUT EXPECT SOMEWHAT LOWER VALUES OF 800 - 1600 J/KG 50 HPA-MLCAPE VALUES GIVEN GFS'S PROBLEMS WITH BOUNDARY LAYER MOISTURE. BOTH LOW-LEVEL AND DEEP-LAYER SHEAR WILL BE QUITE MARGINAL, SO EXPECT SEVERE THREAT TO BE RELATIVELY LOW. HOWEVER, GIVEN THAT MID-LEVELS ARE FORECAST TO BE QUITE DRY, STRONG WIND GUSTS MAY ACCOMPANY SOME OF THE STORMS. THESE WILL, HOWEVER, GENARALLY NOT EXCEED THE SEVERE LIMIT OF 50 KNOTS. SOME MARGINALLY SEVERE LARGE HAIL OF IS ALSO POSSIBLE, GIVEN THE DEGREE OF INSTABILITY. THE OVERALL THREAT SEEMS TO BE TOO LOW TO WARRANT A SLGT RISK AT THE MOMENT. BUT, IF LATER ANALYSES SHOW THAT EITHER CAPE OR STRENGTH OF THE DYNAMICS OF THE SYSTEM HAVE BEEN UNDERESTIMATED AN UPGRADE TO SLGT RISK MAY BE DECIDED UPON.

...NORTHERN ITALY...
GFS PRODUCES 2000-2500 J/KG 30HPA MLCAPE IN THE PO-VALLEY REGION, WHICH SEEMS TO BE REASINABLE PER YESTERDAY'S SURFACE OBSERVATIONS. LOW SHEAR CONDITIONS IMPLY MAIN CONVECTIVE MODE WILL BE SINGLE CELLS OR MULTICELLS ORGANISED BY TOPOGRAPHY OR AT RANDOM. GIVEN AMOUNT OF INSTABILTY A FEW STORMS MAY PRODUCE SOME LARGE HAIL, POSSIBLY EXCEEDING THE SEVERE LIMIT OF 2.0 CM. ALSO, SOME STRONG GUSTS ARE NOT RULED OUT. OVERALL THREAT, HOWEVER, SEEMS TO BE TOO MARGINAL TO WARRANT A SLIGHT RISK AT THIS MOMENT.

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