DAY 1 CONVECTIVE OUTLOOK
VALID 17Z THU 27/02 - 06Z FRI 28/02 2003
ISSUED: 27/02 17:31Z
FORECASTER: GATZEN

GENERAL THUNDERSTORMS ARE FORECAST ACROSS WESTERN EUROPE

GENERAL THUNDERSTORMS ARE FORECAST ACROSS WESTERN MEDITERRANEAN AND JOINING NORTHERN AFRICA

SYNOPSIS

UPPER RIDGE OVER NORTHERN/ CENTRAL EUROPE WEAKENS ... WHILE WESTERLY CURRENT BEGINS TO SPRAWL EASTWARD. SHORT-WAVE TROUGH HAS REACHED WESTERN EUROPE AND IS FORECASTED TO CUT OFF OVER WESTERN MEDITERRANEAN AND NORTHERN AFRICA.

DISCUSSION

...WESTERN FRANCE...
SOME THUNDERSTROMS HAVE FORMED IN THE RANGE OF MENTIONED SHORT-WAVE TROUGH. TEMPS SHOW RELATIVELY HUMID BOUNDARY LAYER BUT NOT STRONG INSTABILITY. SHEAR IS WEAK AND THUNDERSTORMS SHOULD DIE SOME HOURS AFTER SUNSET WHILE SPREADING NORTHWARD.

...WESTERN MEDITERRANEAN...
THUNDERSTORMS HAVE FORMED WITHIN WARM AIR ADVECTION REGIME DOWNSTREAM OF BEGINNING CUT OFF. SURFACE LOW OVER SOUTHWESTERN MEDITERRANEAN UP TO NORTHERN AFRICA SUPPORTS WARM AIR ADVECTION FROM THE SOUTHEAST. TEMP OF SARDINIA SHOWS HUMID BOUNDARY LAYER AND DIRECTIONAL SHEAR WITH SOUTHEASTERLY SURFACE WINDS AND SOUTHWESTERLY CURRENT WITHIN THE MIDDLE TROPOSPHERE. THE ABSENCE OF STEEP LAPSE RATES AND DRY LAYERS ABOVE THE BOUNDARY LAYER AND LITTLE SHEAR DUE TU WEAK WINDS DOESN'T ARGUE FOR STRONG THUNDERSTORM DEVELOPMENT, HAIL OR STRONG WIND GUSTS. CONVECTION SHOULD SPREAD NORTH- AND EASTWARD WITH MODERATE LIGHTNING ACTIVITY AND HEAVY RAINFALL.

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