Forecast Update
Valid: Mon 10 Mar 2008 12:00 to Tue 11 Mar 2008 06:00 UTC
Issued: Mon 10 Mar 2008 13:36
Forecaster: GROENEMEIJER

SYNOPSIS

Refer to convective forecast

UPDATE MESSAGE

Threat of briefly rotating updrafts appears to persist over southern England behind this mornings cold frontal passage, as 200-400 m2/s2 storm-relative helicity and low level shear near 20 m/s in the 0-1 km layer are present within the postfrontal returning polar air-mass. Showers and thunderstorms are currently ongoing over southern England to the southeast of the surface low over Wales. These may be able to develop rotating updrafts as they profit from the strong shear. The threat of a tornadoes and severe convectively-induced winds will likely persist with these storms while they move eastward, until early evening when shear deteriorates and storm coverage decreases.