Storm Forecast
Valid: Mon 05 Oct 2009 06:00 to Tue 06 Oct 2009 06:00 UTC
Issued: Sun 04 Oct 2009 20:58
Forecaster: SCHLENCZEK

A level 1 was issued for W Iberia mainly for excessive precipitation.

SYNOPSIS

An occluding low pressure system over SE Finland moves eastward into NW Russia. Some convection should be expected with the trough axis which will cross the Baltic States in the early morning hours, and also with the cold front over NW Russia.

An upper cut-off low near the Azores leads to advection of a tropical airmass towards Iberia and extreme W Morocco. Heavy rainfall is expected in extreme W Iberia where some low-end instability is forecast in a region with high effective PWAT values.

Another upper level disturbance is placed over the E Mediterranean. Showers and thunderstorms are forecast for parts of the Aegean Sea and the western half of Turkey.

In most parts of southern Europe, warm and stable conditions will continue.

DISCUSSION

..extreme W Iberia...

Although CAPE should not exceed a few hundred J/kg, strong moisture advection due to intense SWerly winds at lower levels may favor a large area of precipitation with embedded multicells. Storms may affect the same area for several hours which leads to excessive precipitation and local flooding.

...France, W Germany...

A strong SWerly flow advects very warm and moist air into central / eastern France. Some instability is predicted by GFS near the warm front of a low over NW France and isolated thunderstorms are possible. Low level winds reach values around 20 m/s which may allow strong gusts but most of them should stay sub-severe. Showers and thunderstorms will also affect W Germany in the late evening hours.

...Baltic States...

Near the trough axis, showers and thunderstorms may form and strong winds with 20 - 25 m/s at 850hPa could lead to isolated severe wind gusts, especially with narrow convective lines that may form. During the morning hours, instability should decrease rapidly and a categorical threat level is not warranted.