CONVECTIVE FORECAST
VALID 06Z SAT 27/12 - 06Z SUN 28/12 2003
ISSUED: 26/12 18:06Z
FORECASTER: DAHL

General thunderstorms are forecast across Eastern Mediterranean Sea.

SYNOPSIS

Vigorous Atlantic upper long-wave trough is slowly migrating east ... with several vort maxima present at its periphery. Vort max ATTM over the British Isles ... is currently supporting cyclogenesis over extreme N Brish Isles and over the northern North Sea. Models offer quite inconsistent solutions as to the development/impact of a second vort max which will reach the Channel towards Saturday evening. GME 00Z solution is fostered by the GME 12Z run which does not show any hints of cyclogenesis in association with this vort max ... while GFS 12Z ... MM5 12Z BOLAM 00Z and Meso ETA 00Z offer a rather aggressive scenario with quite intense cyclogenesis over the northern Gulf of Biscay and the Channel Saturday evening/night.

DISCUSSION

...Western France ... BeNeLux States ...


Primary focus for convective development will be the cyclone over the Channel. Along the leading edge of the associated cold front ... there appears to be a slight chance for strongly forced line convection with isolated TSTMS which could augment the strong/severe mesoscale gradient flow. However ... current lack of knowledge about the thermodynamic profiles in the immediate pre-frontal environment ... about the vertical-motion structure along the leading edge of the front and general uncertainty as to the development of the cyclone ... preclude issuance of a GEN TSTM area at the moment. If later OBS suggest the formation of line convection along the front ... an update could be necessary.

...Central Europe...


Thermal gradient along the cold front trailing from the cyclone ATTM over N England is expected to weaken during the day. Though the rain band along the front will likely be convectively enhanced ... TSTMS are rather unlikely ... and a GEN TSTM area is not necessary ATTM. However ... any convection that forms along the front would likely be accompanied with very gusty winds ... possibly exceeding severe levels owing to vertical momentum transfer.

... E Mediterranean...


Over the E Mediterranean Sea ... a few Cb's will likely accompany the EWD progressing vort max ATTM over the Aegean/Greece. Weak thermodynamic and kinematic profiles suggest that severe TSTM threat will be quite low with this activity though a few waterspouts cannot be ruled out.

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