Storm Forecast
Valid: Mon 18 Dec 2006 06:00 to Tue 19 Dec 2006 06:00 UTC
Issued: Sun 17 Dec 2006 16:43
Forecaster: GROENEMEIJER

SYNOPSIS

Monday at 06:00 UTC... a broad trough stretches from northern Scandinavia to western Europe. A number of smaller troughs move around its periphery.

DISCUSSION

Mediterranean...

A shortwave trough initially stretching from Sicily to northern Libya is expected to accelerate eastward and reach the eastern Aegean Sea Tuesday morning. It is filled with relatively cool air in the mid- and upper troposphere, creating weak latent instability, and a favourable environment for scattered thunderstorms.
Upstream... a shortwave trough over northern Iberia is expected to move into the western Mediterranean region, destabilizing the troposphere there. Storms are expected especially over southern parts of the Western Mediterranean during the second half of the forecast period.

Northwestern Iberia, Bay of Biscay...

An intense mid/upper trough over Ireland should move southward over the Bay of Biscay and reach northwestern Spain on Tuesday morning. Rising motion ahead of the system is expected to cause more than sufficient lift and destabilization to allow scattered thunderstorms to develop. These will likely affect northern and northwestern Spain from Monday evening onward and later northern Portugal, too. Rather weak low-level winds suggests the chance of strong and/or severe gusts and other severe phenomena will be small.