CONVECTIVE FORECAST
VALID 06Z SAT 07/02 - 06Z SUN 08/02 2004
ISSUED: 06/02 20:12Z
FORECASTER: DAHL

General thunderstorms are forecast across the E parts of the UK ... N France ... BeNeLux ... NW Germany.

SYNOPSIS

Upper trough ATTM over the E Atlantic off the British Isels ... will dig SE and reach the central Mediterranean and the N and central Balkan States by Sunday 06Z. Associated low-level cold front ... ATTM curving from NW Spain along the continental European NW coast ... into E/SE Europe ... will rapidly cross central Europe ... and sag into N Spain ... central Mediterranean and the N Balkan States early Sunday morning.

DISCUSSION

...E parts of the UK ... N France ... BeNeLux ... NW Germany...
In the deep post-frontal mixed polar air mass ... TSTMS will likely develop ahead of vigorous vort max which will rapidly cross the North Sea and W-central Europe during the second half of the FCST period. Development of a comma cloud appears likely ... however ... loss of diabatic heating over the continent as the system reaches the NW coast of N France ... BeNeLux and Germany late Saturday night ... could be detrimental to the system ... and TSTM threat is expected to decrease farther inland. However ... low-level and deep-layer shear magnitude will be quite strong ... and broad facette of severe weather may accompany this feature especially in coastal regions ... primarily severe straight-line winds ... though some hail and maybe a brief tornado or two cannot be discounted is shallow supercells manage to form. Situation will be monitored for a possible upgrade.

...Central Europe...
Narrow plume of pre-frontal moist subtropical-Atlantic air mass appears to be largely stable ... however ... a few soundings reveal some potential for convection ... e.g. De Bilt 12Z ascent ... featuring steep mid-level lapse rates of nearly 10 K/km ... or saturated/neutral profiles up to ca. 700 hPa ... the latter of which is currently promoting the formation of a narrow convective rain band along the leading edge of the cold front. Chance exists that this narrow/shallow line convection will be maintained at least along parts of the front through the period ... if so ... a few TSTMS will likely accompany the front passage ... likely producing very gusty winds. However ... current thinking is that TSTMS will be sub-severe and too isolated for a GEN TSTM area.

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