CONVECTIVE FORECAST
VALID Sat 19 Nov 06:00 - Sun 20 Nov 06:00 2005 (UTC)
ISSUED: 19 Nov 00:31 (UTC)
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across the Aegean region.

SYNOPSIS

Deep synoptic-scale trough will remain anchored over much of NRN ... central and ERN Europe ... with several vort maxima revolving around its periphery. Like on Thursday ... weak SRN stream vort max over the SW Mediterranean is expected to phase with peripheral vort max of the large-scale trough ... and to affect the S Ionian as well as the Aegean region on Saturday. Fairly intense baroclinic zone will stretch from the S Gulf of Biscay across the central Mediterranean and the S Balkans into the eastern Ukraine by Saturday 06Z ... with cyclogenesis expected along this boundary ahead of the Ionian/Aegean vort max over the Aegean region early in the period. Otherwise ... intense and rather large quasi-stationary cut-off low is present off the Iberian Atlantic coast ... with WAA regime at its E side affecting the W Iberian Peninsula.

DISCUSSION

...Aegean region...
Allover scenario is not too dissimilar from last Thursday's ... though thermodynamic fields are expected to be substantially weaker due mainly to the absence of the EML and weaker LL moisture ... so that MLCAPE should only be on the order of a few hundred j/kg. However ... WSWLY mid-level flow of 20 to 25 m/s ... SLY/SWLY 850 hPa flow 10 to 15 m/s ... and further backed SFC flow ... should be supportive of isolated severe evolution despite weak thermodynamic setup. Also ... LCLs may be rather low ... with little/no capping so that any supercell that manages to form should be capable of developing low-level rotation with an attendant tornado threat. However ... main threats will be marginally severe wind/hail events ... altogether marginally warranting a SLGT.

...Portugal...
Scattered TSTMS will likely continue in WAA regime affecting Portugal and western Spain. It seems that TSTMS will tend to be elevated ... and thus not profit from rather strong LL shear ... though an isolated updraft may be able to tap boundary-layer air/helicity and to attain rotation. In this case ... an isolated wind/hail event ... and maybe a brief tornado would be possible. Threat is quite conditional however ... also ... coverage of TSTMS should remain rather low.

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