TORRO CONVECTIVE DISCUSSION 2007/003

TORRO CONVECTIVE DISCUSSION has been issued at 16:30GMT on Saturday 10th February 2007

Valid from/until: 16:30 12:00 GMT on Saturday 10th February/Sunday 11th February 2007 for the following regions of the United Kingdom & Eire:

S Eire

S Wales

S England

Channel Is

THREATS

Isolated tornadoes (close to southern coasts/in the Channel Is), convective gusts to 50-60mph, occasional cloud-ground lightning, hail to 20mm diameter and heavy rain are possible in and close to the advisory area. The tornado risk is mainly overnight tonight, and largely confined to southern coastal counties. Squally winds are possible anywhere in the area.

Squally winds are also expected after the passage of the frontal system, as heavy showers/thunderstorms move through. Coastal counties are mainly at risk from this second feature.

 

SYNOPSIS

Deep low to the WSW of SW Eire will move slowly towards the UK. The associated upper trough will overspread a moisture plume, with a fairly well marked triple point expected to pass across portions of the DISCUSSION area overnight. This is marked by a small area of instability, along with some pronounced low level wind shear, including directional shear. This brings the highest risk of thunder/tornadoes to S Eire and S England overnight. Further inlands, thunder is still possible, but with somewhat lower instability, squally winds seem the bigger threat here.

Following on from the cold frontal passage, the well-marked upper trough will bring squally showers/thunderstorms across the same region overnight/tomorrow morning, in an environment on strong unidirectional shear. This brings the risk of severe wind gusts and fairly large hail.


A WATCH is not deemed appropriate for this situation, given the uncertainties in convective initiation along the front. If convection develops more widely, a WATCH may be issued.

Forecaster: RPK