CONVECTIVE FORECAST
VALID 11Z THU 05/06 - 06Z FRI 06/06 2003
ISSUED: 05/06 10:43Z
FORECASTER: GATZEN

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL EUROPE

SYNOPSIS

UPPER TROUGH SITUATED OVER WESTERN EUROPE. DOWNSTREAM, UPPER RIDGE COVERS MUCH OF EUROPE WITH AN AXIS EXTENDING TO SCANDINAVIA. OVER EASTERN CENTRAL MEDITERRANEAN ... A CUT-OFF LOW IS SITUATED.

DISCUSSION

...CENTRAL EUROPE...
OVER CENTRAL AND CENTRAL SOUTHERN EUROPE WARM AND INSTABLE AIRMASS IS SITUATED. 00 UTC-SOUNDINGS INDICATE A RELATIVELY THIN MOIST BOUNDARY LAYER AND A WELL DEVELOPED EML ABOVE. MODELS SUGGEST LOW CIN AND RELATIVELY HIGH CAPE VALUES IN THE AFTERNOON, AND THUNDERSTORMS SHOULD LIKELY FORM DURING THE DAY. AGAIN, SOUTHWESTERLY FLOW OVER THE NORTHWESTERN HALF OF EUROPE SHOULD BE THE FOCUS OF SEVERE CONVECTION. WITHIN THIS JET, A SHORT WAVE TROUGH EXTENDS FROM GREAT BRITAIN INTO IBERIAN PENINSULA. ALONG ITS EASTERN FLANK, A JET STREAK IS VISIBLE ON WATER VAPOR IMAGE. MODEL FORECAST SUGGESTS THAT THIS SHORT-WAVE TROUGH WILL SEPARATE INTO TWO PARTS, A SOUTHERN PART MIGRATING EASTWARD INTO SOUTHERN FRANCE, AND A NORTHERN PART CROSSING NORTHERN CENTRAL EUROPE WITHIN THE DAY. AT THE SURFACE ... FRONTAL BOUNDARY OVER WESTERN EUROPE WILL MOVE EASTWARD OVER NORTHERN CENTRAL EUROPE WHILE IT REMAINS OVER SOUTHERN CENTRAL EUROPE. LATEST SATELLITE IMAGE SHOWS STRATIFORM CLOUDS IN THE RANGE OF FRONTAL BOUNDARY OVER NORTHWESTERN GERMANY AND CENTRAL FRANCE AND MOSTLY CLEAR SKY TO THE SOUTHEAST, WHERE SURFACE TEMPERATURE HAS RISEN UP TO 30 C WITH DEWPOINTS AROUND 15 C AND FIRST CONVECTION IS DEVELOPING SUPPORTED BY OROGRAPHY AND OUTFLOW BOUNDARIES. IN THE NEXT HOURS ... THUNDERSTORMS SHOULD DEVELOP SOUTHEAST OF THE FRONTAL BOUNDARY OVER GERMANY AND FRANCE. DEEP LAYER WIND SHEAR SHOULD BE ADEQUATE FOR STORM ORGANIZATION FROM EASTERN FRANCE INTO NORTHERN POLAND, AND SUPERCELLS MAY FORM. LARGE HAIL, STRONG WIND GUSTS AND HEAVY RAIN SHOULD BE THE MAIN SEVERE THREAT. TO THE SOUTH ... WEAK DEEP LAYER SHEAR WILL NOT SUPPORT ORGANIZED THUNDERSTORMS. HOWEVER ... OROGRAPHIC ENHANCED SRH COULD LEAD TO ISOLATED SUPERCELLS WITH A CHANCE OF LARGE HAIL AND DAMAGING WIND GUSTS DUE TO RELATIVELY LARGE CAPE AND DRY AND WELL MIXED BOUNDARY LAYER. IN THE AFTERNOON/ EVENING ... BOLAM SUGGESTS SURFACE LOW OVER SOUTHEASTERN GERMANY MOVING NORTHEASTWARD. FRONTAL WAVE ALONG THIS LOW SHOULD LEAD TO WARM AIR ADVECTION OVER CZECH REPUBLIC, EASTERN GERMANY AND WESTERN POLAND. CONVECTION OVER CENTRAL AND SOUTHERN GERMANY SHOULD MERGE INTO ONE OR TWO MCS/ BOW ECHOS WITHIN THE EVENING, MOVING NORTHEASTWARD. HEAVY RAIN, LARGE HAIL AND SEVERE WIND GUSTS SHOULD BE POSSIBLE.

#