CONVECTIVE FORECAST
VALID 06Z THU 17/04 - 06Z FRI 18/04 2003
ISSUED: 16/04 18:18Z
CORRECTED
FORECASTER: GATZEN

THERE ARE GENERAL THUNDERSTORMS FORECAST OVER PARTS OF IBERIA, NORTHERN ITALY, THE NORTHWESTERN BALKANS AND PARTS OF THE SOUTH-CENTRAL MEDITERRANEAN.

SYNOPSIS

UPPER RIDGE IS PRESENT OVER NORTHERN CENTRAL EUROPE. OVER SOUTHERN CENTRAL EUROPE, WEAK THERMAL TROUGH LEADS TO WEAK INSTABILITY. TO THE SOUTH, CUT-OFF TROUGH IS FORECAST TO MIGRATE EASTWARD INTO SOUTHEASTERN MEDITERRANEAN. OVER THE EASTERN NORTH-ATLANTIC, SOUTHERLY FLOW AND WARM AIR ADVECTION WILL REMAIN.

DISCUSSION

...BALKANS, NORTHERN ITALY...
UNDERNEATH THERMAL 500 HPA- TROUGH WEAK INSTABILITY SHOULD BE POSSIBLE DURING THE DAY. SOME ISOLATED THUNDERSTORMS ARE FORECAST AT THE AFTERNOON. SEVERE STORMS ARE NOT FORECAST, AS CAPE AND VERTICAL SHEAR SHOULD BE RATHER LOW.

...SOUTHEASTERN MEDITERRANEAN...
CUT-OFF LOW PRESENT AT THIS TIME OVER NORTHERN AFRICA WILL MOVE EASTWARD, ENHANCING WARM AIR ADVECTION OVER EASTERN AND CENTRAL MEDITERRANEAN. STORMS SHOULD FORM DOWNSTREAM OF THIS TROUGH. AS 300 HPA WINDS ARE MODERATELY STRONG, SOME OF THE THUNDERSTORMS COULD PRODUCE STRONG DOWNDRAFT GUSTS. ACCORDING TO EASTERLY SURFACE WINDS, RELATIVLY STRONG LOW-LEVEL SHEAR IS FORECAST. HOWEVER... AS BOUNDARY LAYER REMAINS RELATIVELY COOL, SURFACE BASED STORMS ARE NOT EXPECTED.

...SOUTHWESTERN EUROPE...
SOME SCATTERED THUNDERSTORMS COULD FORM DUE TO DIURNAL HEATING. ALONG FRONTAL BOUNDARY OF NORTHERN ATLANTIC TROUGH, COLD FRONT OF ATLANTIC SURFACE LOW WILL EFFECT PORTUGAL AND WESTERN SPAIN. SOME EMBEBBED THUNDERSTORMS SHOULD BE POSSIBLE DURING THE EVENING/NIGHT.

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