CONVECTIVE FORECAST
VALID 06Z TUE 03/06 - 06Z WED 04/06 2003
ISSUED: 02/06 16:56Z
FORECASTER: DAHL

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NE FRANCE ... BENELUX AND W GERMANY.

GENERAL THUNDERSTORMS ARE FORECAST ACROSS CENTRAL AND SOUTHERN EUROPE.

SYNOPSIS

INTENSE WEST ATLANTIC UPPER LONG-WAVE TROUGH WILL CONTINUE TO AMPLIFY AND REMAIN NEARLY STATIONARY DURING THE PERIOD. AHEAD OF THE WAVY LOW-LEVEL FRONTAL ZONE ASSOCIATED WITH THIS TROUGH ... WARM/MOIST AIR IS ADVECTED INTO CENTRAL EUROPE. GFS CAPE FORECASTS APPEAR TO BE MORE REASONABLE THAN DURING THE PAST FEW DAYS ... AND OVER PORTIONS OF FRANCE ... GERMANY ... ITALY AND THE BALKAN STATES MLCAPE IN EXCESS OF 1500 J/KG MAY INDEED BE PRESENT LATE IN THE AFTERNOON.

DISCUSSION

...NE GERMANY/DENMARK...
BOLAM 850 HPA THETA-E FIELDS INDICATE A PLUME OF HIGH THETA-E AHEAD OF THE COLD FRONT ... WHICH IS EXPECTED TO STRETCH ACROSS SPAIN ... FRANCE ... GERMANY INTO THE NORTH SEA TOMORROW MORNING. WITHIN THIS PLUME ... MLCAPE HAS CLIMBED TO 1000 TO 1500 J/KG. AT THE EASTERN EDGE OF THE THETA-E POCKET ... A WELL-DEFINED SFC CONVERGENCE LINE HAS FORMED WHICH SHOULD MOVE INTO EASTERN PORTIONS OF GERMANY AND DENMARK IN THE COURSE OF TUESDAY. INITIATION IS QUESTIONABLE GIVEN QUITE WEAK UPPER SUPPORT ... 500/300 HPA CVA FIELDS SUGGEST RATHER ILL-DEFINED LOBES OF CVA WHICH WILL CROSS CENTRAL EUROPE DURING THE DAY ... ONLY CLEAR SIGNAL IS A BAND OF 300 HPA CVA WHICH SHOULD OVERSPREAD E FRANCE ... BENELUX AND W GERMANY LATE IN THE AFTERNOON. CONVERGENCE ALONG THE COLD FRONT ANALYZED A FEW HUNDRED KM WEST OF THE WIND-SHIFT LINE ... IS EXPECTED TO BE QUITE SHALLOW/WEAK ... AND CONVECTIVE INITIATION IS QUESTIONABLE AT THIS LOCATION AS WELL.

PRIND THAT ISOLATED TSTMS WILL DEVELOP ALONG THE PRE-FRONTAL WIND-SHIFT LINE OVER EASTERN GERMANY AND DENMARK ... WHICH COULD MOVE EAST AND REACH W POLAND LATE IN THE AFTERNOON IN CASE A DEEP/COMMON COLD POOL IS REALIZED. IN THIS CASE STORM-RELATIVE WINDS WOULD INCREASE ... AND GIVEN SELY SURFACE WINDS ... SOMEWHAT ENHANCED SRH MAY BE IN PLACE. AN ISOLATED MARGINALLY SEVERE HAIL EVENT OR TWO WOULD BE POSSIBLE WITH THIS SCENARIO. HOWEVER ... DEEP-LAYER SHEAR IS EXPECTED TO ON THE ORDER OF ONLY 20 KNOTS ... AIRMASS E OF THE WIND-SHIFT LINE IS EXPECTED TO BE ONLY MARGINALLY UNSTABLE ... AND CONFIDENCE THAT STORMS WILL ORGANIZE/MOVE EAST AWAY FROM THE CONVERGENCE LINE IS RATHER LOW. ALSO ... CONVECTIVE DEBRIS/WEAK MID-LEVEL CONVECTION COULD LIMIT INSOLATION INTO LATE MORNING. HOWEVER ... AN UPGRADE TO SLIGHT RISK MAY BE NECESSARY TOMORROW IF EITHER CAPE OR SHEAR IS HIGHER THAN CURRENTLY EXPECTED.

...FRANCE...BENELUX...W GERMANY...
THOUGH NO WELL-DEFINED SURFACE FEATURE IS APPARENT ON SFC WIND/PRESSURE FORECASTS ... ANOTHER POCKET OF HIGH 850 HPA THETA-E WILL MOVE ACROSS FRANCE AND W GERMANY DURING THE AFTERNOON/NIGHT PER BOLAM. THIS REGION SHOULD ALSO BE AFFECTED BY WEAK DCVA-RELATED ASCENT.

TSTMS SHOULD DEVELOP DURING THE AFTERNOON ALONG OROGRAPHIC FEATURES OVER SW GERMANY ... SWITZERLAND AND E FRANCE. MORE WIDESPREAD CONVECTION IS EXPECTED DURING LATE EVENING/NIGHT WITH THE THETA-E ADVECTION REGIME OVER THE WESTERN HALF OF GERMANY AND THE BENELUX STATES. ONE OR MORE LARGER SLIGHTLY ELEVATED MCSS COULD FORM ... WITH AN ATTENDANT THREAT OF LOCAL FLASH FLOODING AND ISOLATED LARGE HAIL.

...BALKAN ... ITALY...
MAINLY DIURNALLY DRIVEN TSTMS ARE EXPECTED AGAIN OVER THE BALKAN STATES AND OVER ITALY. SHEAR WILL GENERALLY BE WUITE WEAK ... SUGGESTING THAT PRIMARY MODE WILL BE SHORT-LIVED CELLS ... WHICH ARE CAPABLE OF PRODUCING STRONG WIND GUSTS AND SMALL HAIL THOUGH. ORGANIZED SEVERE STORMS ARE RATHER UNLIKELY ... BUT AN ISOLATED SEVERE HAIL/WIND EVENT OR TWO WILL LIKELY OCCUR WHERE LARGE LOW-LEVEL SRH CAN BE REALIZED ... E.G. OVER THE MOUNTAINOUS TERRAIN OVER THE WESTERN BALKAN STATES. ALSO ... SMALL-SCALE VORT MAX IS EXPECTED TO SLOWLY CROSS THE ADRIATIC SEA ... AND ASSOCIATED MESOSCALE WIND FIELD MAY YIELD DEEP-LAYER SHEAR OF 20 TO 30 KNOTS ... WHICH MAY BE SUFFICIENT FOR MULTICELLULAR STORMS IF LARGE CAPES ARE INDEED REALIZED.

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