CONVECTIVE FORECAST
VALID 06Z SUN 04/04 - 06Z MON 05/04 2004
ISSUED: 03/04 20:58Z
FORECASTER: DAHL

General thunderstorms are forecast across east-central Europe ... west-cebtral Europe and the British Isles.

General thunderstorms are forecast across the central Mediterranean.

SYNOPSIS

Upper short-wave trough over W Poland/W Slovakia by Sunday 00Z ... is progged to continue to de-amplify as it moves into the upper ridge over NE and E-central Europe. Long-wave trough over the NE Atlantic is slowly translating eastward into central Europe ... attaining increasingly negative tilt during the period. Several small perturbations are present at its periphery. Large quasi-stationary low-pressure system centered SE of Iceland is accompanying this trough at the surface. Quiescent conditions prevailing otherwise.

DISCUSSION

...east-central Europe...
Downstream from the weakening lead short-wave trough ... plume of warm/subtropical air mass will likely remain fairly stable ... and given weakening UVVs ... TSTM threat should be rather low. Saturday's 12Z ascents indicate relatively deep SFC-based layer with moist/neutral profiles ... and chance exists that beneath narrow band of Q-vector convergence ... mainly covering W Poland by Sunday 12Z per GFS ... a few showers and TSTMS develop. Marginal setup suggests that severe evolution is quite unlikely.

...west-central Europe ... British Isles...
Upstream ... vigorous vort max rotating about the main Atlantic trough ... will overspread central Europe ... and weaken late in the period like its predecessor. Convective evolution along the associated cold front is quite uncertain ATTM ... but it looks that lapse rates will likely be too weak to allow for appreciable CAPE. In the wake of the front ... cellular convection is present already. As UVVs are advertised to persist in the post-frontal environment by model guidance ... convection will likely rejuvenate with insolation over the British Isles and over primarily the WRN half of central Europe. Models diverge with respect to the exact position/timing of the peripheral vort maxima ... but allover scenario is quite similar. Expect mesoscale regions of enhanced convection with scattered TSTMS ahead of these vort maxima. Shear will be rather strong with 20 to 30 m/s ... and small probabilities for supercells and bow echoes exist ... which may locally produce a marginally severe wind/hail event or two.

...central Mediterranean...
In weakly capped/weakly unstable air mass ... diurnally-driven TSTMS may form again over the Italian peninsula ... further TSTMS will likely persist downstream from Mediterranean upper cut-off low.

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