Storm Forecast
Valid: Sat 30 Sep 2006 06:00 to Sun 01 Oct 2006 06:00 UTC
Issued: Fri 29 Sep 2006 17:12
Forecaster: GROENEMEIJER

Saturday at 06:00 UTC... a vertically-stacked low pressure system about 500 km W of Ireland is moving eastward very slowly. On its Srn flank a rather strong westerly mid-level flow is present. SWly winds over Wrn Europe advect moist and relatively warm air, which is slightly unstable.

France, Srn UK...

Latent heat release from the relatively warm eastern-Atlantic waters are forecast to continue convective development over the west coast of France and the Wrn and Srn coasts of Britain and Ireland. During the day storms are expected to increase increase in coverage over land as well. This occurs in response to, albeit weak this time of year, solar heating. Low-level SWly winds are expected to create 0-1 km bulk shear of near 10 m/s over much of France, with local higher and lower values. As the upper-level winds gradually become stronger over the area, an environment favorable of organizing convective storms is expected to form. The amout of instablity to be released (a few 100's of J/kg MLCAPE), is however forecast to be small. Any forcing for upward vertical motion should be weak until the evening hours. As a result, the threat of severe weather during the day does not appear to be high enough to warrant a risk level.
However, forcing for upward motion and wind shear are expected to increase during the evening and overnight across western France and the Channel region, and an increasing number of storms is expected to affect the respective coastal areas. Given the increased shear, mesocyclones may form. Possibly a tornado or two, strong gusts and marginally severe hail may result.