Mesoscale Discussion
Valid: Thu 22 Jun 2017 09:00 to Thu 22 Jun 2017 14:00 UTC
Issued: Thu 22 Jun 2017 09:31
Forecaster: GATZEN/PISTOTNIK/BEYER

**Amendment of the MD's expiration time**

This Mesoscale Discussion is issued to highlight latest developments of a severe thunderstorm outbreak in parts of central Europe.

... E Germany ...

On Thursday morning, an intense elevated MCS has developed across the North Sea that currently enters Germany. Latest radar imagery indicates a rear inflow jet and leading bow echo. Wind gusts reached 34 m/s at Helgoland island and even a tornado was observed there despite a very cool boundary layer (2m temperature of only 13°C). It is expected that this storm system will become long-lived and will even intensify as it encounters increasingly warm and moist air and roots down to the surface. In addition, new storms have already formed to its southwest that will merge with the system later on.
The MCS rides a warm front extending from Hamburg to Berlin and further southeast. To the northeast, a dry and cool boundary layer will be present, whereas from the west, humid and unstable air masses are advected as indicated by latest Bergen and Meiningen soundings. Latest observations (09z) indicate 2m temperatures from 22 to 29°C and 2m dewpoints from 8 to 17°C, respectively, from NE to SW across the highlighted area. Additionally, with south-easterly surface flow, strong vertical wind shear and favorably veering profiles are present in the range of the frontal boundary.

We expect that the storm system will propagate even stronger to the right, where a lot of CAPE (possibly up to 2000 J/kg) is present. There is a high risk of widespread severe to extreme gusts in its path, probably maximized in the provinces of Sachsen-Anhalt and Sachsen. An embedded supercell at the SW-ern end poses an additional risk of large hail and a tornado which might even become long-lived or strong!
It is well possible that the storm system will still survive and move into the Czech Republic after 12z.