CONVECTIVE FORECAST
VALID Sun 18 Sep 06:00 - Mon 19 Sep 06:00 2005 (UTC)
ISSUED: 17 Sep 17:22 (UTC)
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the SW and central Mediterranean Sea ... SRN Italy and the western Balkans.

SYNOPSIS

As European upper long-wave trough closes off into an upper cut-off low over the WRN Mediterranean/SW Europe ... strong mid/upper ridging will overspread central parts of Europe. Intense meandering zonal upper frontal zone is stretching across NRN Europe ... affecting the N British Isles and Scandinavia. At low levels ... well pronounced frontal boundary is extending from the SW Mediterranean across the Balkans NEWD into Russia ... altogether making little progress during the period.

DISCUSSION

...central Mediterranean ... Balkans...
TSTMS should continue in warm/most air mass ahead of Mediterranean upper low. Saturday's 12Z ascents reveal CAPE on the order of 500 J/kg ... which is what should be realized on Sunday, as well. Over NRN Italy ... quite large SRH values are progged in WAA regime N/NE of SFC low center. However ... any convection in this regime should remain elevated given dry/stable BL air ... so that effective shear/SRH in the cloud-bearing layer should be rather modest.

Better shear profiles should exist over the SW Mediterranean Sea ... SRN Italy ... and over the SRN Balkans. with 20 to 25 m/s 500 hPa flow and 10+ m/s 850 hPa flow. Expect at least scattered TSTMS to develop in this flow regime ... favorable for severe multicell and supercell storms. Main threats will likely be severe straight-line winds and large hail ... though a few tornadoes should be possible as well.

Over Bulgaria and S Romania ... DLS should be somewhat weaker ... possibly on the order of 15 m/s ... with quite weak LLS. Most of the TSTMS should be subsevere ... though the strongest storms may briefly attain severe levels.

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