CONVECTIVE FORECAST
VALID 11Z WED 29/09 - 06Z THU 30/09 2004
ISSUED: 29/09 10:48Z
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the S Ukraine ... E Moldavia ... E Romania ... Bulgaria ... extreme N Greece ... extreme N Turkey.

General thunderstorms are forecast across SE Europe.

SYNOPSIS

Short-wave trough currently over Benelux/N Germany is expected to close off into a cut-off low and move into Poland by Thursday 06Z ... phasing with quasi-stationary upper trough over SE Europe ... which exhibits several vort maxima at its periphery. Rather vigorous Atlantic short-wave trough is on its way towards the British Isles ... and should reach Ireland late this evening. SFC low now centered over the NE German coast will continue to shift eastwards ... with the trailing cold front expected to curve from E Poland across S Germany into the North Sea by the end of the FCST period. Wavy low-level frontal zone over SE and E Europe should make little eastward progress.

DISCUSSION

...S Ukraine ... E Moldavia ... E Romania ... Bulgaria ... extreme N Greece ... extreme N Turkey...
TSTMS should persist ... and possibly increase in coverage ahead of lifting short-wave trough currently over the Aegean Sea. Degree of CAPE in the pre-frontal air mass is somewhat uncertain ... but indications are that an EML originating from Turkey is present over relatively cool/moist air mass across the Black Sea and adjacent countries to the W ... which might promote MLCAPE on the order of 1000 J/kg.

Strongest forcing for UVV's ... and strongest shear profiles will likely exist over the W portions of the Black Sea and over E Romania and the S Ukraine ... with 30+ m/s at 500 hPa and about 15 m/s at 850 hPa. This should be sufficient for severe TSTMS ... mainly producing large hail and severe straight-line winds. Especially towards the evening ... tornado threat should increase as LCL heights decrease and low-level shear intensifies.

...N Germany ... Benelux...
Indications are that the polar air mass in the wake of the cold front will remain too shallow to support deep enough convective mixing for widespread TSTMS. Best chances for a few TSTMS should exist ahead of small vort max which is expected to reach N Germany late in the evening ... though it is questionable whether this will suffice to compensate for diabatic low-level stabilization. Allover TSTM threat does not appear to be robust enough for a TSTM outlook ATTM though an isolated CG or two could occur.

#