Storm Forecast
Valid: Sat 19 Aug 2006 08:00 to Sun 20 Aug 2006 06:00 UTC
Issued: Sat 19 Aug 2006 08:09
Forecaster: DAHL

SYNOPSIS

Large-scale upper pattern features a slowly eastward progressing deamplifying longwave trough ... which should be centered over the North Sea by the end of the forecast period. Ahead of this trough ... plume of partly unstable low-level air is covering the southeastern half of the forecast area ... with main wavy LL frontal boundary expected to stretch from the SW Mediterranean across N Italy into E Europe on Monday 06Z.

DISCUSSION

southeastern France ... southern Germany ... Czech republic ... N alpine region

Weakly capped and weakly unstable air mass should be present across central Europe NW of the main baroclinic zone. Scattered TSTMS should develop ahead of various small DCVA maxima overspreading France and Germany during the day. It seems that some severe potential exist especially over France ... the N Alpine region and S Germany where DLS should be on the order of 25 m/s. Expect a few small supercells with an attendant hail and severe-wind threat. Maximum LLS is somewhat removed to the N by latest GFS ... and tornadic supercell potential seems to be limited ... though little capping and low LCLs may hint at slightly enhanced potential. Main threats should severe wind gusts and lareg hail however.

France should be overspread by quite vigorous DCVA during Saturday night ... but models do not suggest much precip along the associated SFC cold front. This plus the bad timing indicate that organized severe potential is rather limited with this feature ... though isolated severe-wind-gusts/hail-producing cells could still occur.

N Italy ... N Balkans

Maximum shear of up to 40 m/s is simulated by GFS over the NW Mediterranean ... N Italy and the N Balkans. According to Friday's 12Z and Saturday's 00Z launches ... CAPE is rather weak/non-existent over this region. However ... local moisture acculumation may promote development of at least a few hundred J/kg of CAPE. Also ... EML plume should advect across N Italy (and persist across S Italy) so that stronger CAPE could locally result. Scattered TSTMS are present already across N Italy ... and should spread into the N Balkans during the day. Main threat should again be large hail and severe wind gusts ... but given 100 to 150 J/kg 0-1 km SRH ... and 0-3 km SRH in excess of 300 J/kg ... a brief tornado or two should not be completely discounted.

Belarus

Most unstable air mass appears to reside over E/NE Europe and W Russia ... with MLCAPEs in the 1500 to 2000 J/kg range. Weak frontal wave should affect the Belarus on Saturday ... and should promote rather widespread TSTM initiation. Shear profiles should feature about 15 m/s deep-layer shear and locally 10 m/s 0-1 km shear ... and a few severe multicells and maybe an isolated mesocyclone or two may occur ... which may procude large hail and severe wind gusts. An isolated tornado or two may also occur given favorable LL thermodynamic fields.

Turkey

Very strong therodynamic profiles are present at the S coast of Turkey ... where deeply mixed BL has been advected moist maritime boundary layer (ref. Saturday 00Z sounding from Adana/S Turkey ... featuring 4500 J/kg of CAPE). It seems that scattered afternoon TSTMS will form farther inland ... in inverted-V type environmnts. However ... bulk of activity should occur over the ERN half of Turkey. If a storm formed in the Adana-00-Z environment across S Turkey ... threat for severe winds and large hail would exist.