DAY 1 CONVECTIVE OUTLOOK
VALID 16Z SAT 18/01 - 06Z SUN 19/01 2003
ISSUED: 18/01 15:59Z
FORECASTER: GATZEN

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS IONIC AND SOUTHERN ADRIATIC SEA, ALBANIA AND NORTHERN GREECE

GENERAL THUNDERSTORMS ARE FORECAST ACROSS PARTS OF EASTERN AND CENTRAL MEDITERRANEAN

SYNOPSIS

LARGE LONG-WAVE TROUGH PLACED OVER SOUTHERN EUROPE, EXTENDING TO NORTHERN AFRICA, HAS STARTED TO MIGRATE EASTWARD AND IS FORECASTED TO SEPARATE FROM WESTERLY FLOW OVER WESTERN AND NORTHERN EUROPE. WHILE RELATIVELY HIGH GEOPOTENTIAL OVER EASTERN EUROPE STILL REMAINS, FURTHER ATLANTIC TROUGHS WILL REACH WESTERN AND SOUTHWESTERN EUROPE ... TURNING WESTERN AND CENTRAL EUROPEAN FLOW TO SOUTHWEST.

DISCUSSION

...IONIC AND SOUTHERN ADRIATIC SEA, ALBANIA AND NORTHERN GREECE...
STRONG UPPER JET-STREAK (UP TO 140 KN AT 300 HPA) HAS REACHED SOUTHEASTERN FLANK OF SOUTHERN TROUGH. WHILE THIS TROUGH IS STARTING TO CUT OFF, HIGH VORTICITY-ADVECTION AFFECTS PARTS OF CENTRAL MEDITERRANEAN. RADIOSONDE DATA ABOVE SOUTHERN ITALY SHOW SMALL VALUES OF CIN, AND ALONG EASTWARD MOVING COLDFRONT A LINE OF CONVECTION HAS DEVELOPED OVER IONIC AND SOUTHERN ADRIATIC SEA. AS SOUTHERLY WINDS UP TO 50 KNS ABOVE THE BOUNDARY-LAYER AND MODERATE SOUTHEASTERLY WINDS AT THE SURFACE ... MODERATE SHEAR EXISTS WITHIN THE LOWEST KILOMETER, WHERE SPREAD IS RATHER SMALL. THEREFORE EXISTING STORMS SHOULG LIKELY BECOME SHALLOW SUPERCELLS PRODUCING STRONG WIND-GUSTS, SMALL HAIL AND PROBABLY ONE OR TWO TORNADOS. BECAUSE OF DECREASING WARM-AIR-ADVECTION, THIS ACTIVITY SHOULD HAVE REACHED IT'S MAXIMUM AND CHANCE OF SEVERE STORMS IS DROPPING WITHIN THE NEXT HOURS.

...WESTERN EUROPE...
NEW ATLANTIC TROUGH IS REACHING THE BRITISH ISLES AND IBERIAN PENINSULA WITHIN THE NIGHT. STRONG THETA-E-ADVECTION IS FORECASTED IN FRONT OF PROPAGATING COLDFRONT. SINCE WARM AIRMASS SHOULD BE QUITE STABLE, THUNDERSTORMS ARE NOT FORECASTED. IN THE RANGE OF ATLANTIC TROUGH, DEEP COLD AIRMASS SHOULD PRODUCE BENARD-TYPE CONVECTION WITH A CHANCE THAT THIS CONVECTION COULD ORGANISE INTO A COMMA CLOUD ALONG THE TROUGH AXIS. CONSIDERING STRONG SYNOPTIC-SCALE WINDS ABOVE THE SURFACE, STRONG WIND GUSTS SHOUD BE POSSIBLE WITHIN THIS CONVECTION. HOWEVER ... THIS CONVECTION SHOULD NOT AFFECT WESTERN EUROPE WITHIN THE FORECAST PERIODE.

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