The Alps are diving into winter for a few days! A strong cold front combined with a Genoa Low is going to bring a lot of precipitation to the Alps. On the northern and western sides of the Alps, this will be accompanied by a strong cooling and a rapid drop in the snowline, while in the southern Alps, the southern flow with milder air masses will ensure a higher snowline. On a large scale, we can expect around 30 to 50 centimetres of snow higher up.
Before the precipitation reaches the Alps, it is still quite sunny, especially in the Eastern Alps. Here it will remain dry for a bit longer. On the front of the cold front, the southföhn may once again pick up. On the Hoher Kasten in Switzerland and the Patscherkofel in Austria, wind speeds of 94 and 93 kilometres per hour respectively have already been measured this morning.
During the morning and early afternoon, the first precipitation approaches from the southwest. Soon, the precipitation spreads across the entire French Alps and the rest of the southern Alps. The southwesterly flow ensures that the snowline will initially remain very high, around 2200 to 2500 metres. This evening, the cold front reaches the Alps and the wind turns more to the west. Colder air will flow in and the snowline could drop to around 1500 metres in the Western Alps. During the night, the precipitation continues to spread further eastwards.
The combination of the Genua Low and the inflow of colder air from the west will create a Gegenstromlage tomorrow (see the article on Südstau for more info on a Gegenstromlage), which will not only result in a lot of snow (and rain) on both sides of the alpine main ridge, but also cause the snowline to drop a bit further in Austria. I expect that the higher valleys will turn white, with the snowline dropping to 1000 metres in many places. Although the southern side of the Alps will see a lot of precipitation, here most of it will only fall above 2000 to 2200 metres, further east the snowline will be even higher. Only later in the day tomorrow, the snowline also drops to around 1500 to 1700 metres.
All in all, 30 to 50 centimetres of snow could start falling on a large scale. Frontrunners at the moment seem to be the areas around the alpine main ridge in Austria, from the Ötztal Alps to Salzburgerland. Here, possibly even a bit more could fall. Further west in areas close to the Alpine main ridge, it could also snow a lot, like in the Engadin. The southernmost areas on the southern side may see more precipitation, as mentioned above, but much of it will only be for the high-alpine regions.
While it will continue to snow solidly in the Eastern Alps tomorrow, the morning will be dry in the Western Alps, but the next front is already knocking on the door. From the British Isles, a separate low-pressure core moves southeastward over the Western Alps towards central and southern Italy. With this low-pressure core, another precipitation front will reach the Western Alps and temperatures will also drop some more. Tomorrow afternoon, another 5 to 10 centimetres of snow could fall in the Western Alps with a snowline that could dip just a little below 1500 metres.
Due to increasing influence of the high-pressure area over south-western Europe, snowfall decreases from the west on Saturday. In the southern Alps, northföhn will keep it dry for longer. In Austria, with a northerly flow, it will continue snowing for a bit longer, but here too it will clear up in more and more places during Saturday afternoon and evening. The high pressure area will shift a little further east on Sunday, bringing a south-westerly flow back to the Alps. It will therefore become warmer and sunnier again. With the exception of possibly some precipitation in the middle of next week, it will remain dry.