Storm Forecast
Valid: Thu 04 Dec 2008 06:00 to Fri 05 Dec 2008 06:00 UTC
Issued: Wed 03 Dec 2008 20:13
Forecaster: GATZEN

SYNOPSIS

Low geopotential moves into the British Isles, while an upper trough over central Mediterranean weakens and moves north-eastward. Ahead of this trough, an unseasonable warm air mass spreads into the Black Sea region. Along the cold front over the central Mediterranean, a frontal wave will deepen and moves into Poland during the night.

DISCUSSION

Southern Adriatic and Greece to Bulgaria and southern Romania

Strong warm air advection is present over the southern Balkans throughout the period. Latest soundings over Greece indicate rather steep mid-level lapse rates, while quite most low-level air mass is capped. On Thursday, a quite intense trough over the central Mediterranean will turn northward associated with strong quasi-geostrophic forcing. Lift will likely lead to further destabilization and models indicate CAPE in the order of 500 J/kg over the southern Balkans, but given the cool boundary-layer, elevated convection seems to be most likely. Given the strong wind field and hodographs, rather high helicity is expected, and well-organized convection is forecast. Isolated large hail and severe wind gusts are forecast with supercells. Especially near the coasts of the northern Aegean, low-level buoyancy may be better and a few tornadoes, some of them may be strong, are not ruled out. Convection will likely weaken further north given the cool boundary-layer and weakening dynamics.

The British Isles

Axis of an intense long-wave trough approaching across the British Isles will move eastward in the afternoon and evening hours. A convectively mixed maritime air mass will likely destabilize in the range of this trough axis and showers and thunderstorms are forecast especially from southern Ireland to The Channel region. Given rather strong low-level wind field, mostly non-convective severe wind gusts are not ruled out.