Storm Forecast
Valid: Sat 30 Dec 2006 06:00 to Sun 31 Dec 2006 06:00 UTC
Issued: Fri 29 Dec 2006 17:25
Forecaster: DAHL

SYNOPSIS

Progressive upper flow pattern is establishing over Europe, with rather narrow and intense eastward propagating zonal jet spreading across central Europe. Lead vort max will lift northeastward into the North Sea early in the period while upstream vort maxima will track due east and reach western and central Europe on Saturday evening/night. Strong SFC cyclogenesis is expected to accompany these vort maxima so that major SFC low complex over the N Atlantic and NW Europe will expand south- amd eastwards, covering all except the southern parts of Europe by the end of the forecast period.

DISCUSSION

N France ... S UK ... Benelux ... NW Germany

Major challenge will be forecasting the evolution of convection along the cold front of the vigorous wave cyclone which is progged to track from the S UK and N France into N Germany in the late evening and night hours. Though deep instability is not expected by the models, this setup may favor shallow dryslot convection which could be tied to the mesoscale release of convective instability along the SFC boundary. If this scenario verifies, severe convective wind gusts and also a few tornadoes could occur. Will introduce a level one for the regions most likely affected by the dry intrusion - though the uncertainly of this scenario is emphasized as convection may fail to develop along the cold front altogether. An update may be issued on Saturday if the outcome is becoming clearer during the day but at this time a level one seems to be warranted.