Storm Forecast
Valid: Tue 03 Jan 2017 06:00 to Wed 04 Jan 2017 06:00 UTC
Issued: Mon 02 Jan 2017 22:36
Forecaster: DAFIS

A level 1 was issued for parts of W Denmark, N Germany and Netherlands mainly for severe wind gusts and tornadoes.

SYNOPSIS

A quite-complex weather pattern exists over Europe with several vorticity maxima in the upper and lower parts of the troposphere. NWP models forecast the formation of a fast moving cyclone NW from Scandinavia, crossing the peninsula while deepening during Tuesday and Wednesday. In addition, another cyclone remains offshore west from Portugal where weak instability creates some short-living thunderstorms. Low geopotentials and steep lapse rates over the South Mediterranean will feed some few non-severe thunderstorms with decreasing activity during the forecast period in Central Mediterranean and increasing activity in eastern parts during Wednesday morning.


DISCUSSION

The deepening cyclone that will cross Scandinavia will be the main weather feature during Tuesday and Wednesday. Latest model outputs show the overlap of a dry slot with a cold front near the surface during the night of Tuesday, an area which will lie under the right exit of a 50-55 m/s mid-level jet. Furthermore, 25-30 m/s 850 hPa flow indicates the potential of severe convective gusts at the surface. Onshore moving convection may cause an isolated tornado event where enhanced LLS, SREH and LLCAPE overlap, with better chances near the coasts of Germany. The widest lightning area was issued for offshore regions over the North Sea, with the cold mid-levels atop the warmer sea and hence, better mid-level instability. Finally, graupel or small hail would be another risk inside the level 1 area beside damaging wind gusts and tornadoes.