CONVECTIVE FORECAST
VALID Sun 11 Sep 06:00 - Mon 12 Sep 06:00 2005 (UTC)
ISSUED: 10 Sep 18:47 (UTC)
FORECASTER: DAHL

SYNOPSIS

Upper low ... expected to be centered over the Biscay by Sunday 00Z ... is FCST to progress east and become rather elongated ... stretching from SW Spain to the N Balkans by Monday 06Z. Broad meandering zonal upper frontal zone is persisting across NRN parts of Europe. At low levels ... rather quiescent conditions prevail over central and SRN Europe ... with weak low pressure area present over central Europe.

DISCUSSION

...central Mediterranean...
It seems that at least weak CAPE will be present over the western and central parts of the Mediterranean Sea as well as over the Balkans on Sunday. BL moisture depth seems to vary substantially ... and locally relatively ample CAPE on the order of 1500 J/kg may be realized ... though about 500 J/kg should be more common.

Mid/upper flow should strengthen in response to the EWD shift of the upper-level low. Also ... weak vort maxima traveling along the SE periphery of the upper low should affect the central Mediterranean. Expect scattered TSTMS along and ahead of thermal boundary stretching across the WRN Mediterranean early in the period ... as well as over Italy and over the Balkan States. Especially over the Mediterranean Sea ... activity may be concentrated over the isles. Bulk of activity should occur over N Italy ahead of rather strong vort max in the late afternoon/evening hours.

Deep shear of about 20 m/s should provide kinematic environment supportive of multicellular/bowing storms ... and isolated mesocyclones. Expect strong ... briefly severe straight-line winds and marginally severe hail to be the main threats. Organized-severe threat seems to be too low to warrant a SLGT ATTM.

...Otherwise...
Scattered mainly diurnally driven TSTMS should form across much of central Europe in weakly capped and weakly unstable air mass. Large-scale shear profiles should be fairly weak ... and organized severe threat should be accordinly low. However ... locally enhanced BL moisture and/or enhanced shear (e.g. by orographic features and mesoscale circulations) may briefly provide environment favorable for an isolated marginally severe hail/wind event. Threat is too conditional for a SLGT.

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