Storm Forecast
Valid: Sat 20 Jan 2018 06:00 to Sun 21 Jan 2018 06:00 UTC
Issued: Fri 19 Jan 2018 13:40
Forecaster: PISTOTNIK

No threat levels are issued.

SYNOPSIS

A long-wave trough slowly moves from central into eastern Europe. Embedded in a strong mid-level flow, shorter waves surround its base and move from the northern Balkans (Sat 06 UTC) to the Ukraine (Sun 06 UTC) and from the British Isles (Sat 06 UTC) to the northern Balkans (Sun 06 UTC), respectively, accompanied by surface cyclones of limited intensity. The British Isles are later overspread by a pronounced warm front which brings
The Mediterranean is divided into a cooler and unsettled eastern half, as a cut-off low travels slowly eastward along the Libyan coast, and a mild western half dominated by high pressure.

DISCUSSION

Steep lapse rates in modified polar air and lift of travelling vorticity maxima still creates shower activity with the possibility of isolated, low-topped thunderstorms in a broad corridor from the North Sea across central Europe and the central Mediterranean region to the Aegean Sea. Minimal CAPE and weak vertical wind shear do not suggest a severe weather threat.

Embedded thunderstorms in a transient environment of strong lift and enhanced shear are not ruled out at the cold front of the central European cyclone, when it approaches and hits the Swiss and French Alps in the 12 to 21 UTC time frame. Their heavy snowfall will keep the avalanche risk high, and exposed streets are prone to become impassable or closed as a precaution. Due to the limited confidence in an involvement of thunderstorms, no level 1 area is drawn.