CONVECTIVE FORECAST
VALID 06Z FRI 04/04 - 06Z SAT 05/04 2003
ISSUED: 03/04 22:33Z
FORECASTER: GROENEMEIJER

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN GREECE

GENERAL THUNDERSTORMS ARE FORECAST ACROSS A LARGE PART OF THE MEDITERRANEAN REGION

SYNOPSIS

A STRONG OMEGA-BLOCK IS IN PLACE OVER WESTERN EUROPE. A DEEP TROUGH IS LOCATED OVER EASTERN EUROPE TO THE CENTRAL MEDITERRANEAN. A STRONG JET STREAK IS PRESENT OVER SCANDINAVIA, WHERE A DEEP SURFACE LOW WILL BE FORMED. THE AIR-MASS IN PLACE IS COLD AND STABKE AND WILL NOT ALLOW THE FORMATION OF DEEP CONVECTION. TODAY'S MOST IMPORTANT FEATURE IS ANOTHER STRONG JET STREAK OVER THE NORTHERN SAHARA THAT IS LIFTING NORTHEASTWARD AND SUPPORTS DEEP CONVECTION IN ITS LEFT EXIT REGION.

DISCUSSION

...SOUTHERN GREECE...
LOOKS LIKE EXTENSIVE AREA OF CONVECTION ALONG A SLOWLY MOVING COLD FRONT SOUTH OF SICILY WILL BE ONGOING AT THE BEGINNING OF THE FORECAST PERIOD. SOME MORE ISOLATED CONVECTION IS ONGOING EAST OF THE SYSTEM. A STRONG WSWLY MID/UPPER JET STREAK OVER NORTHERN LIBYA IS FORECAST TO MOVE NORTHEASTWARD. THE COLD FRONT WILL ACCELERATE EASTWARD. AHEAD OF THE FRONT A MARGINALLY UNSTABLE AIR-MASS IS IN PLACE IN WHICH MLCAPE VALUES WILL BE A FEW 100'S OF J/KG ONLY. THE CONVECTION ALONG IT WILL INTENSIFY IN THE MORNING AND EXPAND SOUTHWARD IN RESPONSE TO UVM IN ITS LEFT EXIT REGION. THE SYSTEM IS FORECAST TO AFFECT SOUTHWESTERN GREECE IN THE EVENING. STRONG SPEED SHEAR AND VEERING WINDS WITH HEIGHT WILL LIKELY ALLOW FOR THE DEVELOPMENT OF A LINE ECHO WAVE PATTERN, POSSIBLY WITH EMBEDDED SUPERCELLS. GIVEN VERY LOW LCL HEIGHTS THERE IS A CHANCE OF TORNADOES. HOWEVER, GIVEN ANTICIPATED LINEAR NATURE OF THE SYSTEM, THE GREATEST THREAT WILL BE SEVERE GUSTS AND LARGE HAIL. IF INSTABILITY TURNS OUT TO BE GREATER THAN CURRENTLY ANTICIPATED, AN UPGRADE TO MODERATE RISK MAY BE DECIDED UPON. APART FROM THIS CONVECTION THERE MAY ALSO BE STORMS DEVELOPING AHEAD OF THE SYSTEM OVER SOUTHERN GREECE IN RESPONSE TO DIURNAL HEATING. IF THESE DO DEVELOP, THEY MAY BECOME SUPERCELLS WITH A THREAT OF HAIL, GUSTS AND POSSIBLY A TORNADO.

...SOUTHERN ITALY, ALBANIA AND NORTHERN GREECE...
CLUSTERED THUNDERSTORMS WILL BE PRESENT NEAR A TRAILING BACK-BENT OCCLUSION. VERY HIGH AMOUNTS OF PRECIPITATION ARE FORECAST OVER SICILY THIS NIGHT AND TOMORROW MORNING...AND OVER ALBANIA AND NORTHERN GREECE TOMORROW NIGHT. EXPECT AMOUNTS OF 50 - 100 MM OVER SICILY AND 30 - 60 MM IN THE OTHER REGIONS MENTIONED.

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