Storm Forecast
Valid: Mon 03 Nov 2008 06:00 to Tue 04 Nov 2008 06:00 UTC
Issued: Sun 02 Nov 2008 18:50
Forecaster: DAHL

SYNOPSIS

Main feature this period remains the extensive quasi-stationary upper cyclone covering the SW portions of Europe, and maintaining an intense mid/upper level SWly flow over the western Mediterranean. E of this feature, tongue of warm/moist air is present over the central portions of the Mediterranean. At the surface, a weak low-pressure area will exist over the Biscay region while quiescent conditions prevail elsewhere over southern Europe. Multiple SFC low-pressure systems persist over the N Atlantic and extreme N Europe underneath an ample, meandering upper westerly jet stream.

DISCUSSION

... western Mediterranean regions ...

It seems that the best thermodynamic profiles will exist over the western Mediterranean, east of the low/mid-level thermal ridge spreading across Italy and the Adriatic Sea. Deep convection is expected over the western Mediterranean Sea, where DCVA-related ascent as well as frontogenetic forcing should act as main contributor in maintaining large/mesoscale ascent to sustain the convection. CAPE is anticipated to be rather weak, but DLS of 20 m/s should be present towards the central Mediterranean. Some threat exists for marginally severe hail/wind, though an isolated tornado or two cannot be discounted either, given that GFS advertises small patches of 10 m/s LLS across this region especially towards the end of the period.
Main issue will likely be the non-localized vertical-velocity distribution, which should result in rather widespread convection, which may also prove to be slightly elevated. Still, a marginal level-one threat appears to be warranted.

Towards the end of the period, a vort max should overspread the warm-sector air mass SW of Italy. This may result in better organized convection given stronger capping, and more focused low-level ascent ... along with anticipated strong shear and instability. This activity may well be associated with large hail and damaging wind gusts, and is thus included in a level-one area.