Just a few days ago, the Alps were still in a mild, westerly flow. There was precipitation, but unfortunately not in the right state of aggregation for the most part. What has changed? In this map from January 30, we can see a trough in the North Pacific in front of a small, still rather uninteresting high wedge.
The low over the Aleutian Islands (the long island chain that extends from Alaska into the Pacific) has now strengthened. At the front of the trough, warm air is shoveled far to the north (warm air advection), which supports the formation of a polar high. This polar high pushes everything else a little away from itself, i.e. to the south. This is particularly interesting for us because the Atlantic lows and the frontal zone are also shifting slightly, meaning that disruptions in our area are no longer as warm as they have been recently. The low-pressure activity in the Atlantic will be supported by the influx of cold polar air in the Newfoundland area.
Various alarming disturbances are embedded in the Atlantic lows, which are now moving a little further south. First of all, a cold front will cross the Alps from the northwest today, Wednesday. The front will undulate somewhat and also spread to the south of the Alps, with the main focus of precipitation in the north.
On Thursday, colder air will temporarily flow into the Alpine region before temperatures rise again slightly with an incoming warm front and snowfall increases again towards the afternoon/evening. In lower valleys and in the lowlands, there may be rain in places.
The still widely overcast Friday will be followed by intermediate highs on Saturday, with clearer weather and the onset of a föhn wind. The flow will increasingly turn to the southwest and Südstau is likely to set in on Sunday. Monday looks like a lot of wind and quite widespread stormy and wet weather. The further outlook for the general weather situation is pretty much the same: an active westerly drift will ensure alternating mild/wet and cold conditions (snow in the mountains, rain in the lowlands), with the potential for Italian lows.
And otherwise?
For a while now, the models have been talking about a sudden warming of the stratosphere. The stratosphere lies above the troposphere, where our weather generally takes place. Under certain circumstances, the stratosphere can have a significant influence on what happens on the floor below, especially if there is very sudden, massive warming. In a so-called major warming, the temperature rises by at least 50° within a few days (3-5) and the wind shifts from west to east at an altitude of 10hPa. At the moment, the temperature jump criterion is fulfilled for around February 7, but the wind reversal is not visible, which would mean a strong minor warming. However, a possible major warming has not yet been ruled out. MWs can cause a massive, lasting disruption of the tropospheric polar vortex, which would be decisive for our weather (see polar vortex split).
Long-term forecasts
Yesterday's Groundhog Day traditionally saw expert predictions for the further course of winter. The best-known specialist forecaster, Punxsutawney Phil, announced the imminent end of winter. The media report that he "blinked and then tried to flee", from which it is concluded that he did not see his shadow after leaving his burrow. Ergo: it will be spring. This prediction is primarily supported by Staten Island Chuck, General Beauregard Lee, Malverne Mel, Chattanooga Chuck and Holtsville Hal, as well as Velda the hedgehog. But there are also opposing voices: Milltown Mel, Buckeye Chuck, Dunkirk Dave, as well as Otis the Hedgehog and Terreto the Coati expect another six weeks of winter. Essex Ed's prognosis is still pending, he refused to stand up yesterday.
