CONVECTIVE FORECAST
VALID 06Z SAT 22/01 - 06Z SUN 23/01 2005
ISSUED: 21/01 19:26Z
FORECASTER: DAHL

General thunderstorms are forecast across the E portions of the Mediterranean Sea.

SYNOPSIS

Quite extensive upper trough is covering northern ... central and eastern Europe ... and is expected to expand somewhat as vort maxima revolve around its base. Associated quasistationary large-scale SFC low is centered over the Baltic States ... progged to weaken slowly through the period. Main cold front associated with this system is forecast to curve from the Atlantic across the W British Isles into France ... the N Mediterranean ... the N Balkan States and across E Europe into the Baltic States by Saturday 06Z ... making some SEWD progress as the upper trough expands SE. This supports strong and deep NLY flow across most of central Europe.

DISCUSSION

...central Europe ... especially N and central Germany...
Indications are that cellular convection advecting into central Europe from the North Sea will decrease in depth on Saturday. However ... actual depth of the polar air/convective mixing is quite uncertain ... and models do indicate small patches of negative LIs which may hint at possibility of deep-enough convection for a few lightning strikes ... especially in the N-German coastal regions. As shear profiles should weaken some ... likelihood of organized convection should decrease. Current thinking is that rain/snow/graupel showers may be rather widespread ... especially in N and central Germany ... and maybe spreading as SEWD far as into SE-central Europe ... capable of producing quite gusty winds and possibly a few lightning strikes. However ... TSTM coverage ... and threat for severe convection seems to be rather limited ... and neither a TSTM area nor a SLGT are warranted ATTM.

...SE Mediterranean Sea...
Strong vort max will overspread the Aegean Regions ... GFS and NMM agree on development of CAPE S of the Aegean Sea ahead of the vort max towards the afternoon/evening hours. NMM LGIR forecast sounding indicates saturated dry-adiabatic layer in the lowest km ... which should be an artifact of the model parameterization schemes. Current thinking is that profiles will be nearly neutral. Shear should be sufficiently strong though for an isolated mesocyclone or two (30 m/s at 500 hPa ... 20 m/s at 850 hPa and 10-15 m/s at 10 m AGL per MM5) ... which may cause isolated marginally severe hail ... damaging wind gusts and maybe also a brief tornado. Given quite weak thermodynamic support ... severe threat should be limited and a SLGT does not appear to be necessary.

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