CONVECTIVE FORECAST
VALID Fri 16 Sep 07:00 - Sat 17 Sep 06:00 2005 (UTC)
ISSUED: 16 Sep 07:01 (UTC)
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across central Turkey and parts of the eastern Mediterranean.

There is a slight risk of severe thunderstorms forecast across the SW Mediterannean.

SYNOPSIS

Intense large-scale N-Atlantic upper trough is centered over N Norway ... with vort max currently over the channel region digging SEWD. This system will merge with upper cut-off cyclone present over the SW Iberian Peninsula ... altogether resulting in impressively large ... positively tilted upper trough extending from SE Portugal across central Europe into NW Russia. Meanwhile ... upper low over the Aegean region will weaken and accelerte east. By 12Z ... main ... wavy baroclinic zone coupled with the long-wave trough is expected to stretch from N France across N Poland into NW Russia.

DISCUSSION

...Greece ... Turkey...
CAPE of about 1000 J/kg is present beneath and E of the upper low over the Aegean region. Expect TSTMS to continue throughout the day in the vicinity of this feature. Mid/upper flow is progged to be maximized at the E periphery of the upper low ... providing DLS of about 20 m/s over portions of the E Mediterranean Sea and central Turkey. Especially over the hilly/elevated terrain of Greece and Turkey ... LLS should at least locally be sufficiently strong to support low-level rotation. Expect mainly malticellular structures with imbedded mesocyclones ... which may account for isolated large hail and severe straight-line wind events ... and also a brief tornado or two. Severe threat should be highest across central portions of Turkey where deep shear will be strongest.

...SW Mediterranean...
TSTMS should overspread the SRN Iberian Peninsula during the day ... and move into the western Mediterranean in the late evening hours as vort max merges with European long-wave trough ... spreading the UVVs into the W Mediterranean. This will also result in strengthening of the shear profiles ... especially over the Spanish E coast and the W Mediterranean Isles where friction will be larger than over the Sea ... 20 m/s DLS and about 10 m/s LLS may be realized late in the day. Though thermodynamic profile are uncertain ATTM ... chances of mesocyclones accompanied by marginally severe hail and a few tornadoes seem to exist.

...central Europe...
Many 00Z Soundings over central Europe ahead of the cold front indicate are essentially neutral stratification ... some with rather dry mid/upper levels. Models are coming up with weak CAPE over central and E-central Europe ahead of the front towards the afternoon though it seems difficult to destabilize most of the central European 00Z soundings. Rather remote chance seems to exist that further mid/upper drying may create potential instability which ... upon action of UVVs may result in weak CAPE. If this happens ... shallow TSTMS could form. Given quite strong LL and DLS ... potential for rotating updrafts exists ... capable of producing a brief/weak tornado and some hail. However ... threat is very conditional ... not warranting categorical outlook ATTM.

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