Yesterday we looked back at that pretty awesome PA #18 and the small window of PA #19. If you want to read it again, please check it here. Today we focus on PA #20. There has been a WatchStatus since last Thursday, which turned into an AlertStatus yesterday, and today I'll tell you where to go. The story of yesterday is still going strong, so scroll down to the where to go areas.
Incoming snowfall from the south on Tuesday
The precipitation in the Piemonte will intensify during the night to Wednesday
It will snow on Wednesday in the Piemonte (30-85 cm)
Snowfall in the northern Alps from Wednesday afternoon till Thursday morning
It will snow between Grenoble and Voralberg (5-25 cm)
PA #20 has begun
You can see the first snowfall on the radar already and the satellite images clearly show how the Po Valley is already flooded with clouds. They are the first pinpricks of PA #20.
If we look quickly at the webcams, you can see the contrast between clouds on side and sun on the other. Below the webcam of Rosswald. Rosswald is located in the main alpine ridge just north of the Simplon and you can often see the emerging southern Stau arise. Today, this is also the case. The clouds in the south on the left, the sunny Rhone Valley on the right.
Andermatt is also such a resort. It snows regularly on the Gemsstock during a southern Stau, while it remains dry in the valley. You can already see the clouds from the south, while the sun is still shining in the valley.
It has begun, but it's only the beginning. In the night from Wednesday the snowfall intensifies, especially in the late night and morning it can snow intense in the Piedmont. I expect the most snow (50-80 cm) between the Gran Paradiso and the Mont Viso and unfortunately there aren't that many resorts in this part of the Alps. The snowfall is the strongest in the pre-Alps of this part of the Alps. But rest assured, areas like Sestriere (30-50 cm) and Monte Rosa (20-50 cm) will also get their share. The further east you'll go, the more it will snow. The treeruns will be awesome at the end of the afternoon on Wednesday.
The snowfall will probably also reach the higher parts of areas like Valfréjus, Montgenèvre, Val Cenis and Bonneval sur Arc in France. In the villages it is often (almost) dry, but at the Punta Bagna, Mont de la Plane or the flanks of the Punte d'Andagne you'll find plenty of freshies to make some powder turns when the sun gets out. The same applies to the Ecrins, where the higher parts of La Grave can expect 10-30 cm on Wednesday.
The same applies to villages such as Zermatt and Saas Fee in Switzerland where the snow from the south will hit the mountains. Same in Andermatt, although this time you should not expect that much snow from the south. But fortunately there is some snowfall from the north (incoming cold front from the northwest).
It will snow from Grenoble to Vorarlberg during Wednesday afternoon, when the snow comes from the north. It won't snow that much, but you can locally expect around 25 cm. And that's not bad on a regular Thursday morning.
Warm air will come in on Thursday. There's still a fair amount of moisture in the air and the combination of moisture, warmer air and the strong sun makes the window pretty short. Don't be surprised if the sun (if it comes out) in the course of the day gives way to the so typical gloom clouds that we see in this part of the season. Friday remains unstable on the north side of the Alps, from time to time snow above 1400-1700 meters.
Where to go?
Which brings me to the where to go areas. Yeah, it's exactly the same as yesterday.
Southern Alps West (Larches on Wednesday and Thursday and some sunshine)
Southern Alps Central (Wednesday and Thursday: especially between Monte Rosa and Gotthard)
Western Alps Central (Thursday: especially Valfréjus, Val Cenis and Bonneval sur Arc)
Western Alps North (Thursday: only Saas Fee and Zermatt)
How is it going with the northern Stau of PA #21?
Well, there's a northern Stau coming, but it's probably on the warm side. Warm air is not far away, so chances are that PA #21 is just something for the higher areas in Austria, Switzerland and the north of the French Alps. A snow line around 2000 meters (and sometimes higher) and a lot of rain are coming up. In addition, the exact course is still a question mark. The more west it will be, the less stau and therefore also less orographic cooling.
So, if you want to do a snow dance, wish for a northern stau with a strong northerly component in the current and it should turn out alright. More details on Thursday. Tomorrow an update with pictures of the dump in the Piedmont.