Since the end of last week, we have been in a high-over-low situation, which has now become a kind of omega. High-over-low traditionally means that the Azores high and Iceland low swap places. In the current case, the high is more likely to be found in the area of the British Isles and the low in the Mediterranean region. The blocking effect is nevertheless present: The powerful high reaching far to the north stands in the way of the westward drift and prevents Atlantic lows from reaching us on their usual track. The culprit is located between north-eastern Canada and Greenland: a center of the displaced and still disturbed polar vortex shovels warm air (important for the high) far to the north.
The stratosphere
The stratosphere also plays a role in the background and makes the weather dolls dance in the troposphere. However, it's quite a complicated play and it's difficult to say exactly why a particular puppet is twitching right now. In any case, there was a sudden warming of the stratosphere over the weekend (see DWD Topic of the Day from Sunday). This affects the polar vortex and can result in very persistent blocking layers. The current warming occurred quite late in the winter season and large parts of Eastern Europe have been snow-free for some time anyway, so the continental air flowing into Central Europe from the east is not too cold.
