CONVECTIVE FORECAST
VALID Sun 25 Sep 06:00 - Mon 26 Sep 06:00 2005 (UTC)
ISSUED: 24 Sep 18:11 (UTC)
FORECASTER: DAHL

SYNOPSIS

Atlantic upper trough is expected to cross the British Isles early in the period ... moving across the North Sea into N-central Europe until early Monday morning. Phasing with this feature ... SRN stream vort max is progged to close off into a cut off low over SE Spain/SE Mediterranean Sea late in the period. Downstream ... several weak vort maxima are traveling eastwards along secondary upper frontal zone affecting S Italy ... Greece ... S Turkey and the S Mediterranean Sea. At the SFC ... large high is covering much of E Europe and W Russia. The NRN British Isles will be affected by one of several large/intense SFC lows over the N Atlantic ... but otherwise most of the FCST area will see rather quiescent synoptic conditions.

DISCUSSION

...France ... Benelux ... W Germany...
Elongated DCVA-maximum associated with central/SW European trough will cross the Benelux States ... W Germany and France late in the period. Soundings from this air mass indicate that weak CAPE may develop if either slight mid/upper level cooling occurs ... or if deeper BL moisture will locally be availabe than what has beed sampled by the 12Z ascents. Current indications are that a scattered TSTMS will form towards the afternoon hours over France ... which may spread into the Benelux States and W Germany late in the period. Though about 15 m/s deep shear may evolve over N France ... Benelux and W Germany in the early evening hours ... instability and timing of the trough are rather poor so that severe threat should be rather low.

...Black-Sea region...
MM5 advertises rather strong low-level flow over the N and W Black Sea as well as over the S Ukraine in association with weak cyclogenesis over the Black Sea. While majority of the convection should stay over the Sea ... where SFC friction and LL shear should be somewhat reduced ... a short-lived/small mesocyclone could occur. Weak deep-shear profile and weak thermodynamic fields should limit sever threat though.

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