Storm Forecast
Valid: Sun 03 Jan 2016 06:00 to Mon 04 Jan 2016 06:00 UTC
Issued: Sun 03 Jan 2016 01:06
Forecaster: TASZAREK

A level 1 was issued for W Balkan Peninsula and W Turkey mainly for excessive precipitation.

A level 1 was issued for N France mainly for the risk of severe wind gusts.

SYNOPSIS and DISCUSSION

A main jet stream bordering a cold polar and a warm polar/tropical air mass stretches through Azores, Iberian Peninsula and a Mediterranean. A cold artic air mass covers NE Europe. A trough with a well pronounced occlusion and a warm homogenous center moves into British Isles. A steepening lapse rates and a moderate boundary layer's moisture content (mixing ratio ~ 5-6 g/kg) will provide a few hundredths J/kg of CAPE over the marine areas. Within a convective cloud tops cooler than -10°C and a good lift signal in the center of the trough, an increased probability for the lighting is expected around marine SW edge of British Isles.

A weakly pronounced cold sector away from the main trough passes N France in the late afternoon hours. A convective cells close to the occlusion point are expected to be under the influence of a significant wind shear and thus be capable of producing a severe wind gusts. However, due to marginal or almost absent thermodynamic instability along with insignificant PVA, a presence of convection enabling organization into bowing lines is highly uncertain. In addition, lack of directional wind shear in a vertical also limits the threat for the low-topped mini supercells. Nevertheless, given these issues, a "lower" level 1 is issued to indicate the threat of possible severe wind gusts.

Over SE Europe, a shortwave passes Italy, Balkan Peninsula and Turkey. A combination of a steepening lapse rates (~ 7°C/km) and a boundary layer's moisture up to 7 g/kg provides 400-600 J/kg CAPE. Although a vertical directional and a speed wind shear in the instability zone is not significant, a good signal of PVA and a well-developed free convective layer provide a good conditions for the development of DMC and thus a lightning occurrence (over marine areas). Due to an orographic lift in a perpendicular air flow relative to the mountain ranges along the W Balkan Peninsula edge and a W Turkey, a superimposing almost stationary and a persistent convective and a large-scale precipitation pose a threat for the flash flooding.