CONVECTIVE FORECAST
VALID 06Z WED 02/06 - 06Z THU 03/06 2004
ISSUED: 01/06 23:58Z
FORECASTER: GROENEMEIJER

General thunderstorms are forecast across southern Iberia, much of central Europe, Italy and the Balkans as well as southern Finland, southern Karelia, the Russian Archangelsk adm. region, and the eastern Ukraine.

SYNOPSIS

Wednesday at 06Z...a weak upper low over central Europe is expected to move southward and deepen. On its southwestern flank, a northwesterly jet over western Europe is moving into the central and eastern Mediterranean during the forecast period. A low-pressure area is expected to form over the northwestern Balkans.

DISCUSSION

...Western Germany, northeastern France, Alpine region ...
Scattered thunderstorms are expected to form in a polar air mass over much of central Europe as a few 100's of J/kg MLCAPE should be able to form in response to solar heating. Numerical predictions indicate deep-layer shear should be quite limited over most of the area initially. However, closer to the axis of the aformentioned jet... over northeastern France, southwestern Germany and northwestern Italy, 0-6 km shear over 20 m/s and a few 100's J/kg MLCAPE could be colocated, allowing for organised storms and possibly a few embedded mesocyclones. A marginal risk mainly of large hail will therefore exist in this region.

...Italy...
A few 100's of J/kg CAPE are expected to form over central Italy as wide clearings in the cloud cover should allow for a decent amount of solar heating. A lack of strong upward vertical motion and raises the question if storms, and if so, how many storms will form. Current thinking is orography will aid in the development of a few storms that may advect downstream to the adriatic. 0-6 km shear well in the 20-25 m/s range should allow for updraft rotation, so that a few large hail events may occur as well as a few strong wind gusts. Given that the storm coverage and MLCAPE are expected to be quite low, a risk category seems not to be necessary.

...elsewherer...
Diurnally driven convection may yield a few scattered large hail events mainly over the indicated areas in Spain, Portugal and the central Balkans.

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