CONVECTIVE FORECAST
VALID 06Z FRI 31/12 - 06Z SAT 01/01 2005
ISSUED: 30/12 19:51Z
FORECASTER: GATZEN

General thunderstorms are forecast across eastern and central Mediterranean

General thunderstorms are forecast across parts of northern Europe

SYNOPSIS

Upper westerly jet is directed towards Great Britain and southern Scandinavia. To the south ... broad eastern Atlantic high ridges into central Europe. Over central Mediterranean ... a cut-off low propagates slowly eastward. At lower levels ... mixed polar airmass will remain over northern Scandinavia, while warm maritime airmass will be advected into central Europe. Over eastern Mediterranean ... warm and slightly unstable airmass will be present east of the cut-off low.

DISCUSSION

...Eastern Mediterranean ...
A strong upper jet streak is expected to move northward across eastern Mediterranean along the flank of the cut-off low ... and rather strong deep layer wind shear will be present underneath this jet streak. Affected airmass is characterized by relatively steep low-level lapse rates but poor low-level moisture ... yielding CAPE values in the order of some 100 J/kg. On Friday ... QG forcing should be present as DCVA is expected in the range of small short-wave trough. Showers and thunderstorms are forecast that may organize due to strong deep layer wind shear. ATTM, coverage of thunderstorms seems to be too low to warrant a categorical risk. However ... a few rotating updrafts and/or LEWP are not ruled out ... capable of producing severe wind gusts, large hail and a tornado or two.

...Northern Europe ...
A few thunderstorms may be possible in the range of mixed polar airmass. Strong vertical wind shear will be present ... and some thunderstorms may organize. Severe wind gusts and brief tornadoes are not ruled out in the range of several vort-maxima. Coverage seems to be too low for a SLGT.

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