What an interesting start of the new month! The Alps will go from a strong föhn situation with high temperatures to more cooler conditions. During the weekend it will still be very warm in the Northern Alps because of the föhn, but in the course of Sunday evening a cold front will approach from the west. Cooler and moist air will reach the Northwest Alps, making it possible to expect snow in the higher regions. Our weather model is (too) optimistic and even colours red in some areas, which could result in up to a metre of snow. Other weather models are more pessimistic. So, both the exact timing and amounts are still very uncertain.
Also this year we can experience that october is a typical föhn month. At this time of year, strong depressions regularly approach and increase the air pressure gradient between the Northern and Southern Alps. In addition, the sun is already lower which means that the valley wind system is no longer as strongly developed and the föhn can therefore more easily break through into the valleys. The peak of this föhn episode during the weekend is expected around midday on Sunday. The föhn will be able to break through into the Alpine foreland with very heavy wind gusts in the typical föhn areas, possibly reaching 120 to 140 kilometres per hour. While the föhn situation in the west will most likely be cleared on Sunday evening by the approaching cold front, Austria will have to deal with the powerful föhn until Monday.
What will happen with the approaching snowfall is still very uncertain. The weather models in the past 24 hours have not yet given an unambiguous picture, so we can't talk about the real details yet. According to our weather model, the most snow will fall between the Mont Blanc massif and Engelberg, with up to 30 to 50 centimetres. Higher up, the weather model even shows snow amounts up to 1 metre, but I think that's too optimistic for those regions. Other weather models are much more cautious about the precipitation on the north-west side. In the latest calculations, the low-pressure area over Great Britain seems to be moving a little further north, which means that the precipitation might just graze the north-western Alps and hardly any of the expected precipitation amounts will remain.
Precise amounts are therefore difficult to estimate at this stage, as some things may still change. We shouldn't be surprised if the snow amounts in these areas end up being disappointing. On Monday, some colder air will enter the area and the snow line will drop to 2000 meters. On Monday, a small low pressure area over the Mediterranean will bring a lot of precipitation to the southern Alps, especially around Ticino and Piemonte. I expect by far the most precipitation to fall here too, but the problem is that with temperatures around 10 degrees at 1500 metres, the snow line will be around 3000 metres for a long time. All in all, I think the high altitude areas around the alpen main ridge like Zermatt and Saas Fee will get the most snow with a snowline that slowly drops below 2500 meters.
In the course of Monday, the precipitation also seems to move further to the east, but the weather models don't agree on this yet either. In Austria, especially Vorarlberg can benefit from some snowfall on Monday. Later on, Tirol and Salzburgerland might also see some snowfall with a snowline around 2,000 metres. Large amounts are not expected here. How this weather situation will develop is even more uncertain at this moment. However, it seems that the weather will remain variable in the following days and we can expect snow in the higher regions.