Storm Forecast
Valid: Thu 12 Nov 2015 06:00 to Fri 13 Nov 2015 06:00 UTC
Issued: Wed 11 Nov 2015 22:17
Forecaster: GATZEN

A level 1 was issued for southern Sweden, southern Baltic Sea, southern Baltic States and north-western Belarus mainly for severe wind gusts and to a lesser extent tornadoes.

SYNOPSIS / DISCUSSION

Progressive troughs move rapidly across northern Europe whereas a zonal ridge axis extends over southern Europe. Strongest dynamics are expected with a short-wave trough that is expected to move from southern Scandinavia to the eastern Ukraine during the period. Rich moisture of 6-8 g/kg low-level mixing ration are present ahead of this trough that will partly overlap with steepening lapse rates near the troughs base. Latest Stavanger sounding already indicates low-level CAPE within this air mass and thunderstorms have formed across the northern UK and North Sea. On Thursday, thunderstorms are forecast near the troughs base, spreading across southern Scandinavia, the Baltic Sea, southern Baltic States, Belarus, and Ukraine. Although some low-level stabilization can be expected over eastern Europe, a few storms are not ruled out given the strong dynamics offered by a powerful 50 m/s mid-level jet streak curving around the trough axis. Storms will form in an environment characterized by strong low-level vertical wind shear, exceeding 15 to 20 m/s in the lowest 3 km. Therefore, storms are expected to organize into multicells, forming bowing lines. Main threat is severe wind with these storms. A couple of reports is expected over the path of the trough, requiring a level 1 threat. Furthermore, tornadoes are not ruled out as low-level vertical wind shear is strong. Best potential is near the North and Baltic Sea where low-level buoyancy is best.

More storms are not ruled out along the coast of south-western Norway as well as across the western UK and Ireland. These storms are not expected to profit from strong vertical wind shear. Isolated wind gusts and tornadoes are not ruled out, but a threat level is not issued.