Storm Forecast
Valid: Thu 10 Dec 2009 06:00 to Fri 11 Dec 2009 06:00 UTC
Issued: Wed 09 Dec 2009 12:41
Forecaster: GATZEN

SYNOPSIS

A cut-off low over Greece is expected to move slowly south-eastward at the eastern flank of high geopotential over Iberia. This high is forecast to ridge into north-western Europe during the period, and another low starts to cut-off over Central Europe. While rather warm air masses remain across south-western Europe, the temperature decreases over the north-eastern portions.

DISCUSSION

Aegean and east Mediterranean

In the range of the cut-off low, steep lapse rates are expected given temperatures around -25°C in the 500 hPa-level and rather warm low-level air masses ahead of the surface low. As models do also indicate rich boundary-layer moisture over the warm sea waters, CAPE is forecast especially across the southern Aegean Sea and to the south of Turkey.

While weak winds are forecast in the range of the trough centre, around 20 m/s vertical wind shear evolves in the lowest 5 km at the eastern flank of the cut-off low due to a mid-level southerly jet streak. Storms that manage to form in this region are forecast to be organized. However, weak low-level vertical wind shear and poor buoyancy are expected to limit the severe potential significantly. Storm that evolve further west in the region with weak vertical wind shear are forecast to have a potential of producing waterspouts given rather good low-level buoyancy and low-level convergence.