Last night, a cold front grazed the northwest Alps. It got some 5 to 15 centimetres in the northwestern stau areas. In the remaining parts, the amounts quickly diminished and even remained mostly dry as expected. Some precipitation follows again this afternoon, but now with a sharply rising snowline. It is the start of a winter heatwave with possible temperature records in central Europe.
In this weather report:
After a brief sunny interlude, the warm front will now follow. Precipitation is mainly limited to the French northern Alps and western Switzerland. The snowline will initially still be at around 1,800 metres, but soon the entry of warmer air will cause a rising snowline, which could eventually reach 2,300 to 2,500 metres. Above that, some 15 to 20 centimetres of snow could fall. Further south and in Switzerland, precipitation amounts decrease rapidly. In Switzerland, especially along the alpine edge, around 10 centimetres could still fall, but again so with a high snowline (>2000m).
As written before, tomorrow will be particularly warm for the time of year. With a south-westerly flow, a large portion of warm air will be sent to central Europe. On the northern side of the Alps, föhn will be added, which could give an extra push to maximum temperatures. That temperature records will be broken seems very likely at the moment. In the Northern Alps, 18 to maybe 20 degrees is not unthinkable. It is also warm in the high mountains. The freezing level lies between 3,000 and 3,500 metres.
As I wrote on Wednesday, there will be some temporary snow from the northwest next week. On Monday evening, a (weak) cold front approaches the northwest Alps. Here, some 5 to 15 centimetres could fall. In Austria, it will most likely stay at about 5 centimetres and in the southern Alps even less. Only around Ticino could possibly fall a little more. With the cold front, considerably cooler air also flows in, so we will see snow above 1200 to 1400 metres in most places, dropping to 1000 metres by the end of the snowfall.
After that, the high pressure area in southern Europe seems to strengthen a bit again. Only the Northern Alps can still expect some showers, but generally it will remain dry until next weekend (7-8 January). Nevertheless, the cards seem to be shuffled again from the end of next week onwards. I want to emphasise that we are still talking about the long term and so we still have to consider the uncertainty.
All in all, I see the weather models slowly but surely calculating some more hopeful weather situations. Also, the NAO index (North Atlantic Oscillation) is slowly dropping back from a very positive phase to 0. The current weather situation with depressions following a northerly route with and at the same time a dry and warm Central and Southern Europe is typical of a very positive NAO phase. With the dropping NAO, we also see that the jet stream is not in this stuck pattern as we have seen in the past two weeks. This may again pave the way for depressions to reach central Europe. Of course, for details such as timing and what it will yield, it is still far too early.
NAO is slowly going back from very positive towards neutral (noaa.gov)