Forecast Update
Valid: Thu 06 Dec 2007 21:00 to Fri 07 Dec 2007 06:00 UTC
Issued: Thu 06 Dec 2007 21:44
Forecaster: TUSCHY

SYNOPSIS

Please refer to the outlook, issued at Wed 05 Dec 2007 19:15 UTC.

DISCUSSION

... Central / southern United Kingdom, northern Belgium, the Netherlands and NW Germany...

Confidence is growing that southeastward moving cold front will be the focus for scattered thunderstorms as steepening mid-level lapse rates and unseasonable moist pre-frontal boundary layer airmass result in at least low-end instability release. LL shear and 0-1km helicity values are augmented which points to healthy directional shear at lower levels. Combined with low LCLs, the risk of tornadic cells is augmented throughout the level-1 area.
In addition, wind field at lower levels is quite strong ( 850hPa between 25 and 30m/s ) and an isolated wind gust, matching our criterion can't be ruled out.

Please read the outlook for a more detailed discussion .