Forecast Update
Valid: Wed 09 Apr 2008 16:00 to Thu 10 Apr 2008 06:00 UTC
Issued: Wed 09 Apr 2008 16:59
Forecaster: GROENEMEIJER

+++ CORRECTED GRAMMAR 18:20 +++

SYNOPSIS

Refer to convective forecast...

DISCUSSION

Portugal, S and W Spain...

In a strong SWly flow, unstable air continues to be advected into the Iberian Peninsula. Several small supercells, some embedded within linear convective systems occur within this air-mass characterized by 200-400 J/kg of CAPE and 0-1 km shear near 15 m/s. As shear, especially deeplayer shear is expected to decrese from the NW through the evening, and because of sunset, severe threat should gradually diminish. An exception are the coastal areas of southern Portugal and Spain, where latent heating by warm sea waters may sustain isolated severe storms throught the night. The primary threat of the storms will continue to be severe gusts and perhaps another isolated short-lived tornado. Some marginally severe hail is not excluded either.

E France, W Switzerland, extreme SW Germany...

Isolated thudnerstorms storms have formed in a highly helical flow. Radar indicates a few mini-supercell-like structures, that may bring some large hail, and severe winds locally. An isolated tornado cannot be fully ruled out either. The convective activity should gradually weaken during the late evening and overnight.