CONVECTIVE FORECAST
VALID 06Z SAT 03/04 - 06Z SUN 04/04 2004
ISSUED: 02/04 19:46Z
FORECASTER: DAHL

General thunderstorms are forecast across the Alpine Regions ... E France ... N Italy ... S Germany.

General thunderstorms are forecast across south-central Mediterranean.

SYNOPSIS

SW European upper trough is expected to close off into an upper low during Saturday ... which is progged to move into the S-central MEditerranean Sea by Sunday morning. Northern part of the trough will lift NEWD ... and weaken as it transverses the central European upper ridge. Next trough/attendant frontal system approaching from the Atlantic ... will reach the British Isles and W-central Europe towards Saturday evening. At low levels ... Extensive low-pressure system is covering the NE Atlantic and the British Isles. Quiescent conditions persist across the Mediterranean and much of E Europe.

DISCUSSION

...Alpine Regions ... E France ... N Italy ... S Germany...
Tongue of subtropical air mass is advected northwards E of the SW European trough ... latest soundings reveal that 10+ °C low-level dewpoints are present across the W Mediterranean and S France withing this plume ... with little modification required to render the air mass supportive to deep convection. Current thinking is that a few TSTMS may occur along the cold-frontal boundary over E France early in the period ... and spread E/NE into N Italy ... Switzerland and maybe into S Germany as the trough accelerates NEWD. Moisture will likely struggle to spead far N of the Alps ... and though favorable UVV's are expected to overspread all of Germany during the day ... convective threat appears to be focused primarily to E France ... the W Alpine regions and possibly S Germany/central and E Alps. TSTMS will likely be rather isolated ... and weak kinematic/thermodynamic fields suggest that severe threat will be quite low.

...S-central Mediterranean...
Ahead of the developing upper low/vort max over the Mediterranean ... a few TSTMS may form in the weakly unstable air mass. Cellular convection/scattered TSTMS will likely form beneath the upper thermal low ... however ... shear and instability should be too weak for a significant severe-weather threat ... though small hail may accompany the stronger cells given cold mid/upper level temperatures.

#