Storm Forecast
Valid: Sat 13 May 2006 06:00 to Sun 14 May 2006 06:00 UTC
Issued: Fri 12 May 2006 23:57
Forecaster: DAHL

SYNOPSIS

Broad and slightly meandering upper westery flow has established over Europe ... with weak short-wave trough crossing the central portions of Europe on Saturday. Quite vigorous NRN stream vort max will spread across Scandinavia during the period. At low levels ... Scandinavian vort max is expected to induce rather strong cyclogenesis over Finland ... while rather quiescent conditions prevail over the rest of Europe.

DISCUSSION

E Finland ... extreme NW Russia

Latest GFS and NMM runs advertise weak CAPE over Finland ahead of strong upper trough. Confidence is rather high that /possibly shallow/ lines of TSTMS will develop along and ahead of the associated SFC cold front. Though CAPE will likely be minimal ... indications are that deep/dry CBLs will be in place ... so that in combination with strong linear forcing and strong shear ... substantial chances for an organized severe wind threat should exist.

SW and central Europe

Setup from WRN across central and E Europe appears to be quite marginal. Majority of the soundings reveal inverted-V type profiles over central and E Europe which are conductive to strong evaporatively-chilled downdrafts and accompanying strong outflow winds. These thermodynamic profiles will be imbedded in 10 to 15 m/s deep-layer shear ... and 5 to 10 m/s low-level shear. This suggests that storms may become multicellular with a threat for bowing/line segments which may be accompanied by severe wind gusts and some hail. Farther SW towards SW Germany and France ... richer BL moisture should be in place ... which may result in somewhat stronger CAPE if this moisture underruns the steep low-level lapse rates farther NE. Otherwise CAPE should remain fairly low with nearly neutral profiles.

Altogether ... large scale forcing for UVV will not be extraordinarily strong ... with several ill-defined/small vort maxima crossing W and central Europe and a weak short-wave trough moving across France and Germany during the day. Also ... shear will be marginal ... and CAPE will likely be rather meager. Expect largely non-severe TSTMS which will likely be multicellular ... with the strongest cells being accompanied by severe wind gusts and some hail. An isolated mesocyclone cannot be discounted ... which may augment the hail threat ... but allover confidence in widespread severe is rather low ATTM. Am reluctant to issue a level-one threat for all of SW and central Europe ... and pinpointing an area where severe threat will be maximized seems to be rather challanging/impossible ATTM. Mesoscale evolution on Saturday needs to be awaited ... with the possibility of an upgrade to level-one if focus of severe TSTM development becomes clearer than it is at the moment.