Storm Forecast
Valid: Sun 01 Oct 2006 06:00 to Mon 02 Oct 2006 06:00 UTC
Issued: Sat 30 Sep 2006 19:31
Forecaster: DAHL

SYNOPSIS

Large-scale Atlantic upper trough will attain strong positive tilt as vort max at its W periphery closes off into a cut-off cyclone ... leading to a strong and broad WSWly upper flow over western and central parts of Europe. Atlantic synoptic-scale SFC low will make some eastward progress and reach the North Sea late in the period ... thereby advecting warm/moist air into central and NE portions of Europe.

DISCUSSION

E France ... Benelux ... W and N Germany

Rather widespread TSTMS should develop in weakly unstable air mass which is rapidly being advected across central into NE Europe. Mesoscale foci may be weak wave cyclones along the main frontal boundary. Shear profiles should strengthen in association with a jet streak nosing into central Europe during the day ... and isolated severe TSTMS may occur. Especially N France ... Benelux ... W and S Germany are progged to be affected by 10 m/s LLS and 20 m/s DLS. This coupled with rather low LCL heights and minimal capping may support evolution of mesocyclones which may spawn a few short-lived tornadoes. Also ... severe straight-line wind and large hail may occur.

Though LLS is expected to be rather weak over S France ... CAPE could be somewhat higher given richer LL moisture than farther north. Little CIN and strong LL buoyancy may again be in place ... compensating for the weak LLS ... and a few severe TSTMS ... capable of large hail ... damaging wind gusts and a tornado or two may occur.

S British Isles

10 m/s LLS and about 15 m/s DLS are expected over the S British Isles ... which should be affected by cellular polar-air convection. It seems that an isolated and small tornadic mesocyclone may occur ... but threat is too low to warrant a categorical risk.