Tornado outbreak (14 April 2012) in the Great Plains

The NOAA Storm Prediction Center (SPC) issued a high risk for the 14th of April two days before the event took place. The overall area with moderate to high risk for severe thunderstorms and tornados already suggested that this day would become very tensing. Not only from a synoptical point of view.
With this post I just want to sum up a little bit of the material that is out there in the net. Meaning links, radar images, satellite pictures and tornado images and videos of course. Feel free to add anything that is missed in the post in the comment section.


Wave cyclone Christoph over Germany

After a period of a rather boring weather constellation over mid-europe in the past few weeks the cyclones strike back. At 2011/12/04 a wave cyclone passes Germany and will bring a lot of wind especially in the southern parts of Germany.

Let’s have a look at the synoptic setup:

A longwave through lies over the atlantic and europe. The result is a mean westerly flow with fastly travelling fronts and precipation. This will mitigate the aridity of the last few weeks when nearly no precipitation was measured.
A steering low over the Norway with a core pressure of 955 hPa influences two wave cyclones embedded in the mean westerly flow. These two waves will pass Germany throughout the day. The most noticeable effects will be the enduring rain/snow and the storm gusts.


Temperature inversion over Germany in November 2011


Over the last weeks a very stable high pressure dominated weather situation was oberserved over Germany and Eastern Europe. While the same situation in summer would have resulted in a very warm period, the same isn’t true at autumn. One can observe relative high temperatures up to 15°C in 850hPa, but the temperature at the surface was often much cooler – known as a temperature inversion. Especially when it was foggy the whole day.
This is not an uncommon situation at autumn, but the very stable weather situation over this long time-period is definitely not oberserved all day at this region.

Flash flood in Northern Italy

Foehn winds in the Alpine area are definitely not a unconvenient situation during autumn. But the current synoptic setup results has some extreme effects. On the southern part of the Alpine arc the accumulated rain exceeded several 100mm while in Germany temperatures up to 24 °C were observed.

Let’s have a look at the current synoptic setup: