Storm Forecast
Valid: Thu 18 Feb 2010 06:00 to Fri 19 Feb 2010 06:00 UTC
Issued: Wed 17 Feb 2010 21:15
Forecaster: GATZEN

A level 1 was issued for south-western Adriatic and Turkey mainly for excessive rain.

A level 1 was issued for southern Spain and the Balearic Islands mainly for excessive rain.

SYNOPSIS

To the south of low geopotential over Europe, the frontal zone is situated over the Mediterranean. An amplified trough move from the Canaric Islands across the Iberian Peninsula into the west Mediterranean Sea. Downstream, another short-wave trough is forecast to amplify while moving across the Adriatic Sea into the Aegean and Turkey. In the range of both troughs, rather cold mid-level air masses will likely lead to instability given the rather moist boundary-layer across the Mediterranean. A tongue of warm air spreading northward ahead of the western trough will be associated with stable conditions.

DISCUSSION

Adriatic to Turkey

In the range of the eastward moving short-wave trough, a rather cold mid-level air mass spreads across the central and eastern Mediterranean. Given a low-level mixing ratio of around 7 g/kg and moist-neutral to slightly unstable lapse rates, weak instability will likely develop that may increase further west as the trough amplifies and strong QG forcing goes on. To the north of the low, widespread convection seems to be possible, and embedded thunderstorms may evolve. The main potential of these storms will be excessive rain in regions where upslope flow will provide additional lift. Further south, QG forcing will weaken underneath the anticyclonic flank of the jet axis. A convective line may develop along the cold front, though, that will become deeper in the northern portions, where some lightning may also be possible. Given rather strong vertical wind shear of about 15 m/s in the lowest 3 km due to a strong low-level jet, strong winds may be possible in the range of bowing segments. A tornado is also not ruled out given favorably veering profiles. The best potential seems to exxist in the range of the occlusion point.

South-west Mediterranean

An amplified trough moves across north-western Africa and travels into the Mediterranean. Ahead of this trough, a tongue of very warm tropical air mass spreads northward. This air mass will likely be stable given the rather cool boundary-layer. However, very strong QG forcing in the range of a 40 m/s 500 hPa jet streak may lead to elevated convection. The best potential of surface-based convection is forecast in the region of the Balearic Islands, where the strong forcing may lead to neutral lapse rates. Given the strong vertical wind shear and more than 25 m/s wind speed at the 850 hPa level, bowing lines capable of producing severe wind gusts are not ruled out. In the range of the trough axis, models indicate that a frontel boundary will remain from southern Spanin to the Balearic Islands, and deep moist convection may go on, and excessive rain is not ruled out.