CONVECTIVE FORECAST
VALID 06Z FRI 18/04 - 06Z SAT 19/04 2003
ISSUED: 17/04 18:17Z
FORECASTER: GATZEN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS EASTERN MEDITERRANEAN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS NORTHERNEASTERN IBERIAN PENINSULA, SOUTHERN FRANCE, NORTHERN ITALY

GENERAL THUNDERSTORMS ARE FORECAST ACROSS SOUTHERN AND NORTHWESTERN IBERIAN PENINSULA

SYNOPSIS

UPPER RIDGE SITUATED OVER NORTHWESTERN EUROPE. WITHIN THE SOUTHERN BRANCH OF POLAR JETSTREAM ... TWO RELATIVELY WEAK TROUGHS PLACED WEST OF IBERIAN PENINSULA AND OVER EASTERN EUROPE. OVER EASTERN CENTRAL EUROPE ... CUT OFF MIGRATES WESTWARD.

DISCUSSION

...EASTERN MEDITERRANEAN...
UPPER TROUGH PROPAGATES EASTWARD ... AND COLD AIR ADVECTION IS FORECAST DURING THE FORECAST PERIODE. SOME SHOWERS MAY FORM. HOWEVER ... ALONG THE TROUGH AXIS AND NEAR THE SURFACE LOW SOME EMBEBBED THUNDERSTORMS ARE NOT EXCLUDED. SEVERE STORMS ARE NOT FORECAST.

...NORTHERNEASTERN IBERIAN PENINSULA, SOUTHERN FRANCE, NORTHERN ITALY...
IN THE RANGE OF UPPER THERMAL TROUGH ... SOME THUNDERSTORMS COULD FORM DUE TO DIURNAL HEATING AND OROGRAPHIC SUPPORT. ACTIVITY SHOULD BE QUITE WEAK AS SOUNDINGS DO NOT INDICATE MUCH MOISTURE WITHIN THE BOUNDARY LAYER.

...SOUTHERN AND NORTHWESTERN IBERIAN PENINSULA...
ALONG FRONTAL BOUNDARY OF ATLANTIC SURFACE LOW ... FRONTAL WAVE WILL FORM OVER PORTUGAL/SPAIN. ASSOCIATED LIFT SHOULD LEAD TO STRATIFORM RAIN OVER MUCH OF NORTHERN IBERIAN PENINSULA. SOME EMBEBBED THUNDERSTORMS ARE POSSIBLE DURING THE EVENING, WHEN EFFECTED AIRMASS WILL DESTABILIZE DUE TO DIURNAL HEATING. OVER SOUTHERN IBERIAN PENINSULA ... SOME ELEVATED THUNDERSTORMS COULD REACH FORECAST AREA AS UPPER SHORT-WAVE WILL MIGRATE OVER NORTHERN AFRICA. AS BOUNDARY LAYER SHOULD BE COOL POTENTIAL FOR SURFACED BASED STORMS IS RATHER LOW. SEVERE STORMS ARE NOT FORECAST.

#