VALID 06Z SAT 16/11 - 06Z SUN 17/11 2002
ISSUED: 16/11 01:36Z
FORECASTER: GROENEMEIJER

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE WESTERN MEDITERRANEAN AND ITALY

GENERAL THUNDERSTORMS ARE FORECAST ACROSS ATLANTIC WATERS WEST OF FRANCE AND SPAIN, THE WESTERN MEDITERRENEAN AND PARTS OF ITALY

SYNOPSIS

N-S ORIENTATED UPPER TROUGH FROM U.K. TO IBERIAN PENINSULA IS ALMOST STATIONARY, A STRONG SOUTHERLY JET IS PRESENT OVER THE WESTERN MEDITERRANEAN. A VORTICITY MAXIMUM IS ROUNDING THE BASE OF THE TROUGH ATTM AND EXPECTED NEAR CORSICA AND SARDINIA AROUND NOON.

DISCUSSION

...WESTERN MEDITERRENEAN AND ITALY...
AIR MASS OVER REGION WILL BE STABLE TO MARGINALLY UNSTABLE. AHEAD OF UPPER TROUGH A NARROW ZONE OF HIGHER INSTABILTY WITH SBLI INDICES BETWEEN -2 AND -4. CURRENT LIRE AND LICT SOUNDINGS SHOW VERY HIGH SRH VALUES OF 600 - 800 M2/S2. UNDER AN ELEVATED MIXED LAYER A SHALLOW MARITIME BOUNDARY LAYER HAS DEVELOPED INCREASING IN DEPTH TOWARDS THE NORTH. LINEAR FORCING AND STRONG OUTFLOW WILL LIKELY INDUCE FORMATION OF A LINEAR MCS. SOME TORNADOES MAY OCCUR GIVEN HIGH HELICITY VALUES. VERY STRONG /50KT @ 850 HPA/ LOW-LEVEL WINDS AND EVAPORATIVE COOLING/ENHANCEMENT OF DOWNDRAFTS IN ELEVATED MIXED LAYER WILL POSE A THREAT OF VERY HIGH GUSTS. THERE IS ALSO A SMALL CHANCE OF LARGE HAIL.

...SOUTHERN ALPINE REGION...
STRONG UPSLOPE FLOW OF MOIST AIR WILL LEAD TO HEAVY RAINFALL ON SOUTHERN FLANKS OF THE ALPS. THERE WILL LIKELY BE FLOODING PROBLEMS IN MANY PLACES.

#