CONVECTIVE FORECAST
VALID 06Z SUN 14/03 - 06Z MON 15/03 2004
ISSUED: 13/03 13:56Z
FORECASTER: DAHL

General thunderstorms are forecast across the SW Mediterranean Sea ... SE Spain.

SYNOPSIS

Zonal upper flow pattern is expected to overspread NW and central Europe as W-European upper longwave trough closes off into an upper cut-off low. East European upper ridge will desperse ... with its southern part remaining anchored over the central Mediterranean ... and with its northern part quickly moving into Russia ahead of the zonal flow regime. The British Isles ... the North Sea and N-central Europe will be affected by a series of short-wave troughs imbedded in the WLY upper flow. SW European cut-off will make little eastward progress and move into NE Morocco/NW Algeria. At low levels ... WAA will continue over the SW Mediterranean Sea ahead of the upper low ... while SWLY low-level flow will establish over W and central parts of Europe at the SE periphery of extensive Atlantic low-pressure system.

DISCUSSION

...SW Mediterranean Sea ... SE Spain...
Patches of relatively moist low-level air are present over the W Mediterranean Sea as revealed by Saturday's LIEE ascents. As this air mass is overspread by dry/mixed air from the Sahara Desert ... weakly unstable thermodynamic profiles are expected to develop late on Sunday. DCVA regime rotating about the Algerian upper cut-off low ... is expected to overspread the weakly unstable air mass Sunday evening/night ... also ... low-level warm advection will contribute to UVVs ... and formation of possibly elevated TSTMS towards Sunday evening is expected. TSTMS may congeal into one or more larger clusters ... and advect into eastern Spain by early Monday morning. Rather dry mid levels may support some hail ... but severe evolution is rather unlikely owing to overall weak thermodynamic and kinematic fields.

...British Isles ... north-central Europe...
It appears that modified polar air masses in the wake of the occluded frontal systems accompanying the short-wave troughs will be rather shallow ... low-level CAA and DAVA in the wake of the frontal systems will not be very supportive to convective development in the narrow zones of mixed/modified polar air. Though a few rain showers may occur ... TSTM threat looks to be rather low ATTM.

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