Due to the influence of low pressure, it will snow a lot higher up in the Alps until Monday. Especially the Italian Piedmont region can expect quite a lot of snow. It's time to take a closer look at the details of this expected snowfall.
First, the precipitation in the southern part of Piedmont today and tomorrow. The snowfall will be limited to most of the southern regions with some 10 to 30 centimetres of snow in the high mountains. Today the snowline will be around 1500-1800 metres. Further north, the amounts will decrease quickly. In the rest of the Alps it will be mostly dry and, apart from some high clouds, fairly sunny today. The southern high flow will transport some Saharan dust to the Alps again.
Tomorrow, the depression over the Mediterranean Sea will move further to the east, so the southeastern Alps and later also the northeastern side will have to deal with precipitation. I expect the most around the Julian Alps with 20 to 30 centimeters above 2000 meters. In the other regions you'll see that the precipitation amounts will be a lot lower.
The developments for the weekend are very interesting. A low pressure area is approaching from the west and will be over France. With a southern flow, we can expect a lot of precipitation. The supply of mild air will cause the snowline to be quite high at first. I expect that the precipitation will only come down as snow above 1900 - 2300 metres. In the course of Sunday, the snowline will drop a few hundred metres.
Most of the precipitation in the southwestern Alps will follow in the course of Saturday evening when the low-pressure area moves further east. The south wind will increase in the French Alps first and later on also in Piemonte. Higher up, it will be stormy with wind gusts (well) over 100 kilometres per hour. This is also the time when the Northern Alps are increasingly affected by precipitation from the west. On Sunday, particularly in Switzerland, heavy showers can develop, possibly with a clap of thunder. Further east, the föhn suppresses this precipitation for the time being.
If we take a look at the precipitation accumulation map of the European model, we can see that the differences at small distances are enormous. With this southern flow, the Northern Alps should not expect much precipitation with about 5 to 10 centimetres (locally, due to the convective character, perhaps a bit more). The inner alpine areas should expect even less due to the Südföhn. The snowline here is also initially quite high, around 2000 metres, but may drop to 1600 metres in the course of Sunday evening.
The real snowfall amounts are for the Southern Alps and especially for Northern Piemonte. Between Ticino and Turin, half a meter of snow could fall with peaks up to 80 centimetres. Also the French southern Alps will see a lot of precipitation on Saturday because of the southern flow with 20 to 40 centimetres possible here. A large part of this snow will only fall above 2000 metres or temporarily even higher, so these large amounts will only be for the high mountains. Due to these quantities in combination with the temporary very strong southern flow, the avalanche danger will increase considerably.
Most areas in Piedmont are already closed. The lifts in Alagna around Passo Salati are still open until 25 April and Monte Moro near Macugnaga is open every weekend until 1 May. The Swiss areas of Zermatt and Saas-Fee will be able to take advantage of the heavy precipitation peak in the night from Saturday to Sunday. Possibly half a metre of snow will fall here above 2000 metres. Here too, the snowfall will be accompanied by strong winds, which will decrease in the course of Sunday.
As the low-pressure area moves on, the eastern Southern Alps will also have to deal with a lot of precipitation on Sunday. Especially between the eastern Dolomites and the Julian Alps, some 10 to 40 centimetres of snow may fall, locally around the Canin massif perhaps even more. Here too, the snowline will be between 1800 and 2100 metres.
As I said, on the northern side of the Alps first of all there are still föhn conditions. Especially in the course of Saturday, the pressure difference between the Northern and Southern Alps and therefore the Southern föhn will increase considerably. While the föhn will be cleared up from the west in the second half of the night from Saturday to Sunday, the föhn in Austria will persist for longer. Here, the föhn will not end until the evening.
How will it continue? Even after the weekend, it will remain changeable and there may be some snow on the northern side of the Alps due to an upper level low that lingers just north of the Alps. The weather models just differ in details. The European model goes for the supply of colder air, which means that the snow line on the north side might also drop below 1500 metres, but the GFS predicts significantly milder conditions.