We have been looking forward to it for at least a week, and it is almost here: polar air and depressions are moving south and reaching the Alps. The details about snowfall, wind, and temperature will still change regularly due to the limited predictability of the cold-air depressions. Here is the situation that the models are currently showing and a look at the long term: is this early winter a short phase or a lasting one?
A few centimeters for the Northern Alps on Sunday night
The weekend will remain dry and calm with low-hanging clouds in the valleys and periods of sunshine in the mountains. It is milder than the past few days with a freezing level around 2800 meters and about 8 degrees at 1500 meters. The westerly wind will pick up on Sunday afternoon and evening as the first disturbance approaches, which will brush the northern Alps. In the late evening and night to Monday, it will snow lightly in Austria (around and north of the main ridge) and in southern Germany. There will likely be only a few centimeters. It will be calm, only in southern Germany at the foot of the Alps there will be a fairly strong westerly wind. The snow line will drop from 1800 to 1000 meters on Monday morning. The precipitation will quickly disappear, making Monday mostly dry again. Another calm and fairly mild day with a freezing level rising back to 1800 meters.
Precipitation from the west on Tuesday, snow in many places on Wednesday
On Monday and Tuesday, a deepening depression will move from Ireland over the Netherlands towards southern Sweden. The Alps are initially in the warm sector on the southeast side of the depression with positive temperatures below 1800 meters on Tuesday. In Switzerland and France, the westerly wind at altitude will increase to force 7 to 8 with gusts up to 100 km/h in the evening and night to Wednesday. The uplift from the west will cause intensifying precipitation from Tuesday afternoon, much of which will fall as rain below 1800 meters. By morning, the cold sector will reach the Alps, causing the snow line to drop into the valleys. On Wednesday morning, Austria also seems to join the snow party. By Wednesday afternoon, the models predict 20 to 60 centimeters of snow in much of the Alps (see map above), with emphasis on the areas north and west of the main Alpine ridge in a strip from Vorarlberg through central Switzerland and the French Alps to the Ecrins massif. On wind-sensitive slopes, the snow cover can become very irregular. The flow is west, later northwest, causing the southern Alps to receive the least precipitation. Especially northeastern Italy (e.g., Dolomites) seems to remain mostly dry.
Snow (and wind) on Thursday and Friday too
On Thursday, a new depression will appear over France, on a collision course for the Alps. At the front, warm air will be drawn in, causing rain up to about 2000 meters, especially in the French Alps. However, this depression will quickly move through, causing snow to fall in all valleys again by Friday night, this time also south of the main ridge. On Friday morning, we will likely be dealing with a significant NW-stau with lots of snow again for the northern and western Alps. The snow amounts are still difficult to estimate at this stage, but there is certainly potential for another half meter of snow in many regions. The wind can again play a major role in the formation of the snow cover. Since this depends on the track of the mentioned disturbances, we will bring more details in later updates.
Mild weather to return?
The southern track of disturbances will ensure a snowy week in the Alps with locally a meter of fresh snow in total. In the long term, disturbances will likely return to their familiar place on the Atlantic. The Alps will then end up in an anti-wintry southwesterly flow from next weekend. We hope, of course, that the weather maps will still change in winter’s favor. More on this later.
