During the last couple of days, things have changed on the weather charts. The retour d'Est that seemed to be coming for Piemonte a couple of days ago has weakened a bit, but there is still snowfall for this region on the weather charts for Thursday. After that, the rest of the Alps seem to be next. From the middle of the week on, we dive into a changeable and snowy phase where every part of the Alps will benefit from.
Today, the Northern Alps are already experiencing a considerable cooling down after a mild and sunny weekend. The cooling of the weak cold front is, however, hardly accompanied by precipitation. In the stau areas, it may snow lightly for a few hours above 1000 metres. This snowfall will not last long, as the high-pressure influence from the west increases again quickly behind the precipitation front. At the same time, the south-western Alps will also see some precipitation today, which is linked to the low-pressure system over Sardinia.
Before the Alps enter a more changeable phase, increasing influence of high pressure area over the British Isles will once again provide the conditions we have often seen over the past two weeks: inversion weather. Tomorrow and especially Wednesday, it will be a bit warmer on the north side for a while and in the valleys the persistent fog soup will only be dissolved with difficulty during the day.
Where it can snow heavily from tomorrow onwards is in the Pyrenees. Especially in the southeastern regions, the foundations for the season can be laid in the coming days. In ski areas like Val de Nuria and Vallter 2000, 30 to 40 centimetres of snow are possible, maybe even half a metre. The American model is the only one to calculate the heavy snowfall further west, other models are more in line with the ECMWF. The area of heaviest precipitation with possibly more than 100mm lies further to the east near Perpignan. The snowline during the snowfall will be around 1500 metres.
After the Pyrenees received this snow, the Alps will get their turn later this week as the low pressure area over the Mediterranean Sea slowly but surely moves eastward. First of all, the Southwest Alps (Alpes-Maritimes & Piemonte) will get some fresh snow. On top of the retour d'Est from last week, some 10 to 20 centimetres of snow could fall here. Top conditions for example for Prali, which opens its lifts this weekend with the pre-opening. The Alpes-Maritimes seem to be in the line of fire for the time being, so for example in Isola 2000 some more than 20 centimeters might fall. The snowline is around 1000 to 1200 metres.
Slowly but surely, this precipitation will spread further eastwards. With a slightly higher snowline, the rest of the southern Alps (including the Dolomites) will also get snow. Initially, the Northern Alps are in a weak föhn flow, but from the west cooler air trickles in, clearing this föhn. The snowfall is no longer limited to the Southern Alps and also reaches Austria in particular. The distribution and the amount of precipitation are hard to determine at this moment, but the colder air mass could make it snow in most of the valleys.
This changeable weather will continue into the weekend. The southern location of the jet stream makes it possible for cold air to reach the Alps. The Alps come under the influence of a depression that moves from the North Sea to the southeast. There are still some uncertainties connected to this weather situation over the weekend. While the ECWMF predicts more snow for the Northwest Alps, the GFS predicts another wave of snow for the Southern Alps. It's small shifts in a similar setting that make a big difference.
Looking a bit further, the American model seems to go for a dump in the Northwest Alps. The European model probably sees this as well. Please note that we're talking about the middle of next week, so this is still outside the reliable forecasting period!
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