Storm Forecast
Valid: Thu 25 Oct 2012 06:00 to Fri 26 Oct 2012 06:00 UTC
Issued: Wed 24 Oct 2012 21:33
Forecaster: GATZEN

A level 1 was issued for south-western Iberia mainly for excessive precipitation and tornadoes.

SYNOPSIS

An arctic trough spreads into Scandinavia, leading to cold air advection across northern Europe until the end of the period. South-western Europe is affected by a cut-off low.

Discussion

Iberia and surroundings

A cut-off low moves eastward and affects the Iberian Peninsula. Strong westerly mid-level winds will be present across the southern Iberian Peninsula. Additionally, a strong south-westerly low-level jet will affect the region. Latest soundings indicate that rich low-level moisture is present across the sea surrounding Iberia. This moist air is slightly capped especially to the east as warm mid-level air spreads northward from the Atlas mountains.

Current thinking is that QG forcing at the cyclonically sheared flank of the mid-level jet and low-level convergence/upslope flow will be associated with lift. Especially across the south-western portions, numerous thunderstorms are forecast. Given the strong vertical wind shear, storms will have a good potential to organize. Favourably veering profiles in the southern parts are expected to support mesocyclones capable of producing tornadoes given the strong low-level vertical wind shear. Additionally, the widespread convective activity can result in local flash floods especially in regions with strong upslope flow.

Southern Aegean, southern Turkey

The trough over south-eastern Europe will weaken. At the same time, low-level lapse rates will weaken as well. The potential os waterspouts will decrease as a result. However, a few events are still possible especially in the morning hours. The best potential is expected along the southern coasts of Turkey.

Western Norway

A very cold air mass will spread into Scandinavia, leading to steep lapse rates especially along the western coasts. Although the air mass will be rather dry, low-level moisture is expected to be sufficient to allow for deep moist convection across the Atlantic, especially when this air is lifted by upslope flow along the western coasts. These storms may produce tornadoes given the strong low-level vertical wind shear through-out the period.