Storm Forecast
Valid: Thu 12 Feb 2009 06:00 to Fri 13 Feb 2009 06:00 UTC
Issued: Wed 11 Feb 2009 21:42
Forecaster: GATZEN

SYNOPSIS

Long-wave trough over Europe amplifies into Mediterranean, where quite strong cold air advection is forecast. Ahead of this trough, a strong south-westerly jet streak is present over south-eastern Europe. Underneath this jet streak, a frontal wave migrates across the southern Aegean during the day, leading to some moisture return.

DISCUSSION

Southern Aegean region

Very moist and warm air mass will be removed by a cold front early on Thursday. West of this front, weak convective activity is forecast initially. During the day, models indicate deepening surface pressure in the range of approaching cold front over northern/western Greece, and surface winds are forecast to back to the east of this surface trough. While moist air mass returns ahead of this cold front, mid-level air mass will cool as the upper trough spreads eastward. This will likely associated with increasing instability over southern Aegean region. Although instability and low-level shear are not strong, and most convection will likely be embedded in stratiform rain, moderate deep-layer vertical wind shear will likely lead to some degree of organization. Marginally severe hail and wind gusts are possible. Chance of tornadoes does not seem to be significant for a level 1. Potential seems to be best across the coasts of south-western Turkey, where low-level vertical wind shear and instability may overlap ahead of the surface cold front in the evening hours.

Central Mediterranean

Cold air mass destabilized across the warm sea surface, leading to deep instability. Along the cyclonic flank of the jet streak, some QG lift may also assist for deep moist convection, and given quite low equilibrium temperature, at least some showers may be electrified. As low-level buoyancy is quite strong, a few waterspouts are not ruled out.