CONVECTIVE FORECAST
VALID 06Z SAT 25/09 - 06Z SUN 26/09 2004
ISSUED: 24/09 16:06Z
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the central Mediterranean Sea and teh SE Balkans.

General thunderstorms are forecast across the central Mediterranean and E/SE Europe.

General thunderstorms are forecast across S Finland ... the N Baltic States.

SYNOPSIS

Extensive upper low is located over NRN Europe ... with several short-wave troughs present at its periphery ... one of which ... reaching the N Mediterranean as of Friday afternoon ... is amplifying and is expected to eventually close off into a large upper cut-off low over the central Mediterranean towards the end of the FCST period. Ahead of this feature ... relatively weak cyclogenesis is in progress over N Italy ... which is progged to expand E/NEWD into E Europe and the Balkan States by late Saturday evening. Main low-level baroclinic zone is expected to make southward progress especially over the western portions of Europe ... and to extend from central Russia across E Europe and the central Mediterranean into SW Iberia at Saturday 12Z.

DISCUSSION

...SLGT area...
TSTMS will likely persist along and ahead of the cold front over the central Mediterranean and central Balkan regions ahead of vort maxima pivoting around the developing upper low. CAPE in the pre-frontal air mass will likely range from 500 to 1000 J/kg ... with an EML expected to persist/strengthen especially over the ERN portions of the SLGT area.

500 hPa flow is progged to be on the order of 20+ m/s over the central Mediterranean and the Balkans ... which should be sufficient for severe evolution. Limited low-level shear suggests that tornadoes probably will not be the primary threat ... but damaging wind gusts as well as large hail should occur. Activity may last well into Saturday night/Sunday morning.

...W-central Europe...
In the polar air mass ... depth of convective mixing should generally be quite limited. Chances for a few showers and TSTMS expected to exist over Benelux and W Germany ahead of elongated 500 hPa CVA regime ... though narrow plume of weak low-level theta-e ahead of the vort max may limit strength/depth of convective mixing ... also ... models are reluctant to show positive CAPEs over this region. Will thus not outlook TSTMS ATTM.

...N Baltic States ... S Finland....
Better TSTM threat exists over S Finland and the N Baltic States in the vicinity of strong vort max/thermal low. Weak shear and weak CAPE should limit severe TSTM threat.

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