CONVECTIVE FORECAST
VALID 06Z SAT 31/01 - 06Z SUN 01/02 2004
ISSUED: 30/01 19:41Z
FORECASTER: DAHL

General thunderstorms are forecast across the Aegean Sea and SW Turkey.

SYNOPSIS

Intense westerly upper flow with a series of embedded short-wave troughs will establish across W and central Europe during the period. The first of these troughs is expected to reach W France and the British Isles by Saturday midday ... moving across the North Sea and N Germany into the Baltic Sea by Sunday morning. Second vort max will cross the British Isles late Saturday night/early Sunday morning. Closed upper low over the central Mediterranean is expected to weaken and to continue east ... reaching the E Mediterranean States towards the end of this period. At low levels ... strong cyclogenesis will accompany the first Atlantic vort max ... with the low center being progged to move across the British Isles ... the North Sea and N Germany into the Baltic Sea during the period. Weaker cyclogenesis is expected ahead of the second vort max ... and the developing cyclone will likely remain far off shore over the Atlantic.

DISCUSSION

...British Isels ... France...
Indications are that plume of air mass from the subtropical Atlantic ahead of the first vort max is slightly unstable ... as suggested by currently ongoing TSTMS ... and it appears that a shallow/embedded Cb's will persist mainly along the cold front beneath maximum Q-vector convergence. Primarily the British Isles and W France could see a few lightning strikes during the first half of the day. Convection will likely augment the strong/severe gradient flow ... however ... allover convective threat looks to be pretty low ... and a GEN THUNDER area does not appear necessary ATTM.

Second vort max affecting the British Isles late in the period is posing a bit of a challange ... the thermodynamic properties of the involved warm-sector air mass ahead of the trough are unknown ATTM ... and will have to base the forecast upon GFS CAPE fields ... which suggest that pre-frontal air mass will be quite stable. However ... deeply mixed modified polar air mass is will be present in the post-frontal environment per GFS 12Z solution. However ... strong DAVA/low-level CAA may well limit depth of convective mixing ... and confidence in significant TSTM activity is rather low ATTM. Later development has to be awaited to specify severe TSTM threat accompanying this feature.

...Aegean Sea ... SW Turkey...
Beneath the upper cold pool associated with the central Mediterranean upper low ... a few low-top TSTMS will likely persist over Aegean through the first half of the day ... and gradually decrease in depth as the upper low moves east ... also veering SFC winds will advect increasingy dry low-level air into the region.

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