CONVECTIVE FORECAST
VALID 06Z SUN 10/10 - 06Z MON 11/10 2004
ISSUED: 09/10 18:03Z
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the SW Mediterranean Sea ... N Italy ... N Balkan States.

General thunderstorms are forecast across the Gulf of Biskay ... the Mediterranean and the Balkans.

SYNOPSIS

High-over-low upper flow pattern will persist on Sunday ... with the low centered over the Gulf of Biskay and the high over the North Sea. Extensive SFC high over Scandinavia is progged to expand slightly ... covering all of N and N-central Europe by Monday 06Z. SFC low should persist over the Biskay ... hardly weakening during the period.

DISCUSSION

...SW Mediterranean ... N Italy ... N Balkans...
Vort max at the E periphery of the Biskay upper low is progged to cross the W Mediterranean on Sunday and will likely be focus for potentially severe convective development. W Mediterranean 12Z launches from Saturday reveal general lack of low-level moisture ... and deep EMLs above a shallow SFC-based mixed layer. Over Italy however ... somewhat deeper low-level moisture is present ... yielding CAPEs well in excess of 1000 J/kg. Chances exist that such rich low-level moisture also exists over much of the Sea and that environments will be conductive to deep SFC-based convection.

Deep-layer shear over the W Mediterranean is progged to be on the order of 25 m/s ... with an 850 hPa flow of 10 to 15 m/s ... which should yield sufficient shear for organized severe TSTMS.

Current thinking is that TSTMS will develop early in the day along the cold front roughly stretching from extreme SW Mediterranean into N France by Sunday 06Z ... and especially towards the afternoon over Italy and the Balkans. Mainly elevated TSTMS may also occur along the strong baroclinic zone extending from the central Black Sea into the N Balkans.

Storms in the SLGT area should have the potential for producing severe outflow winds ... large hail and tornadoes given low LCL heights and strong low-level shear.

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