CONVECTIVE FORECAST
VALID 06Z SAT 04/12 - 06Z SUN 05/12 2004
ISSUED: 03/12 20:54Z
FORECASTER: DAHL

General thunderstorms are forecast across the central and W Mediterranean regions.

There is a slight risk of severe thunderstorms forecast across central Mediterranean regions.

SYNOPSIS

Quasi-stationary W-European upper trough is in the process of closing off into a cut-off low ... maintaining SWLY upper flow over the central Mediterranean. SFC low accompanying this feature is expected to deepen slightly over the W Mediterranean Sea late in the period ... promoting moderately strong SELY flow over the central Med. Meandering zonal upper flow with series of SFC lows is present over NRN portions of Europe and the N Atlantic.

DISCUSSION

...central and western Mediterranean regions...
Soundings from Friday 12Z reveal that weak CAPE is present over portions of the central and western Mediterranean Sea ... supported by steep Saharan lapse rates which are advected atop the relatively moist boundary layer. SWLY low-level flow will likely sustain WAA which should be one focus for convective development. Storms in this flow regime may tend to be elevated ... and may not profit from SRH in the lowest 3 km. However ... relatively warm sea waters may allow for SFC based TSTMS ... which could have the potential for becoming supercellular given favorable shear profiles ... with steep low-level lapse rates and low LCL heights possibly supporting an isolated tornado or two. Also ... a few large hail and severe-wind events may occur. Severe TSTM threat should be greatest in the second half on the period when low level wind fields are expected to strengthen. Degree of severe threat is marginally warranting a SLGT.

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