CONVECTIVE FORECAST
VALID Sat 02 Jul 06:00 - Sun 03 Jul 06:00 2005 (UTC)
ISSUED: 01 Jul 21:55 (UTC)
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the SRN Balkans ... Greece ... and the Ionian Sea.

SYNOPSIS

Vigorous Atlantic upper trough is rapidly digging SEWD ... grazing the NW British Isles late in the FCST period ... and inducing unseasonably strong SFC low W of the British Isles during the day. Ahead of this feature ... mid/upper ridging is progged to overspread the central portions of Europe. Downstream upper trough ... reaching the NRN Balkan States late Friday evening ... is expected to close off into an upper cutoff low ... reaching the Aegean by early Sunday morning. Ahead of this feature ... weak cyclogenesis is simulated over the SE Balkans.

DISCUSSION

...Balkans ... Greece...
Thermodynmic profiles across the Balkans and the S-central Mediterranean are quite variable ... due partly to varying depth of low-level moisture beneath convectively mixed air mass (refer e.g. to LICT and LGAT launches from Friday 12Z). Storms will likely inherit this variability ... as will the severe threat posed by them.

Though especially low-level shear profile will likely be subject to substantial local ... mainly orographically induced ... variations ... large-scale shear profiles are expected to be already supportive of organized severe TSTMS with 10 to 15 m/s at 850 hPa ... and about 20 m/s at 500 hPa. Latest MM5 solution suggests that best shear will be present at the NRN ... WRN and SRN periphery of the low-presure system.

Altogether ... it seems that rather widespread convective storms will initiate again ... mainly along orographic features and outflow boundaries left from Friday night's convection. Though main severe threat will vary with the low-level moisture depth ... shear profiles suggest that mesocyclones may form ... capable of producing large hail and severe wind gusts. Those cells that can be sustained in a LICT-Friday-12Z-environment ... with somewhat deeper moisture ... should be capable of producing significant severe weather like very large hail and destructive wind gusts. An isolated tornado may also occur given increasing low-level shear though current indications are that LFC heights may be somewhat high. Also ... bowing line segements may develop ... mainly posing threat for damaging winds. An upgrade to MDT may be required with later outlooks if the evolution of the thermodynamic fields becomes clearer.

Otherwise ... organized severe TSTM threat seems to be negligible owing to weak CAPE/shear.

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