Storm Forecast
Valid: Thu 24 Mar 2011 06:00 to Fri 25 Mar 2011 06:00 UTC
Issued: Wed 23 Mar 2011 14:53
Forecaster: GATZEN

SYNOPSIS / DISCUSSION

An intense arctic trough moves to north-eastern Europe and expands into Scandinavia in the wake of a very strong mid-level north-westerly jet. Over most of Europe, a high is present. Two rather weak cut-off lows at its periphery will affect the east Mediterranean and the Iberian Peninsula.

The former will migrate south-eastward with decreasing influence on the forecast region. Some showers and thunderstorms are forecast initially over the south Aegean Sea and to the south of Turkey. Increasing cold air advection is forecast during the day and storms will gradually move southward. Unfavourably veering profiles and rather weak vertical wind shear and instability will not assist storm organization.

The second cut-off low will affect the Iberian Peninsula with rather cold mid-level air masses. Especially at lower levels, warm air advection is expected from the south-east. To the north of the warm front, rather dry and cool low-level air will lead to stable conditions, and models predict stratiform rain. Increasing low-level moisture in the wake of the warm front will likely assist for showers and thunderstorms over southern Spain during the period. Another region with instability will be the western regions including Portugal. Rather steep lapse rates near the troughs center, a moist low-level southerly flow, and diurnal heating will assist instability realize during the day, although strong lift is absent over most places. Current thinking is that orographic lift will be the main source of lift leading to showers and thunderstorms. Given rather weak vertical wind shear, severe storms are not forecast except for marginally severe hail that may occur with the stronger storms.