PA #10: Lots of snow and higher temperatures


By meteomorris on 26 February 2016 · 6

Wow, this is going to be an interesting weekend. Especially when you have such a passion (or obsession) for the weather like me. From a freeride perspective it's going to be complex. If you want to ride powder this weekend you'll have to do a little bit more than just have a look at the snow maps. That sounds a bit strange right, with so much snow in the forecast? But just like with so many other storms this winter, this storm in the southern Alps ends warmer than it began. That means that the snow line will rise during the snowfall. If you're flexible you can hop over to the north side of the Alps, because the temperatures will drop over there on Monday, with cold snow coming down. And even though it will last another 48 hours before the snow will fall and the devil is in the details, I can already give you some advice. If you are traveling to the Alps the next couple of days and you want to support wePowder and this forecast, book your accommodation using this link. We receive a small percentage of every booking made through this link and this helps us a lot to improve wePowder and advice you even better. Thanks in advance! In this forecast:

  • Super storm Zissi is coming in hard!
  • It will snow heavily in the night from Saturday to Sunday
  • Treeruns are a must
  • Warm air coming in from the north of Africa on Sunday with a rising snow line
  • Snowfall in the northern Alps on Monday
  • The PowderAdvice will be complicated, but interesting

Storm Zissi
Storm Zissi

Super storm Zissi wil hit the 990 mbar (cyclone warning)

What will happen the next couple of days is pretty rare in February. It doesn't happen that often that a low pressure area in the Mediterranean Sea will drop to 990 mbar this time of the year. That's a big storm and it will come in hard, especially on Sunday. These kind of storms are called 'Mediterranean Cyclones) and are characterized by heavy winds (the Sirocco rages with winds above 100 km/h), lots of precipitation (up to 150 mm of rain) and major issues for public life. Roads will be closed due to avalanches, mudslides, flooding and fallen trees. The mix of cold and warm air combined with the moisture from the Mediterranean Sea guarantees fireworks. It's recommended to follow meteoalarm.eu during your road trip.

I'll explain the situation with some extra maps. First, a map of the jet stream. Cold air from the Arctic is moving south via Spain and Portugal and returns back north once it has reached the north of Africa. This is pretty cold at first, but thanks to the jetstream (that's a bit more to the south), some warm air is added above the Sahara desert.

Cold air is getting warmer in the subtropics
Cold air is getting warmer in the subtropics

It looks like this on the temperature maps for Saturday. The green color is the cold air that descends from the north to the south, but the bright red color is the warm air that's transported to the north from the Sahara desert during the weekend.

Air temperature at 1400 meters altitude
Air temperature at 1400 meters altitude

The temperature rise isn't that bad in the southern Alps at first. In fact, it just stays nice and cold on the southern side of the Alps, while the temperature is rising on the north side of the Alps (orange color). All this has to do with the effects of stau and Föhn.

Stau in the south, Föhn in the north

Because the storm hits the southern Alps from the southeast a process called orographic cooling is taking place. So much energy is lost due to the intensity of the precipitation that the temperature will drop and obviously the snow line will drop as well. At the same time, the temperatures are rising in the north of the Alps thanks to a dry wind, which you can see in the Föhn diagram. The first snow arrives in the night from Friday to Saturday. The snow line will be at low altitude and you can already ride some nice powder in the stau of the Monte Rosa, Gran Paradiso and Mont Viso on Saturday. Especially because the snowfall will intensify in the course of Saturday. It will keep on snowing till Sunday morning. One look at the snow maps says it all: red colors!

It's cold on the south side of the Alps
It's cold on the south side of the Alps

The most snow will come down in the southern Piedmont on Saturday. It will snow heavily south of Sestrière. And between Saturday afternoon and Sunday morning I expect lots of snow in the areas south of Sestrière. And I'm more positive than our snow maps. I expect around 100 cm between Friday evening and Sunday morning. That's in the resorts south of Sestrière. You will even see some difference in the Via Lattea. The difference between Montgenèvre in the west and the lifts east of the Col du Sestrière (or east of Sestrière Borgata) can be as much as 60 centimeters or maybe even more. The disadvantage of the resorts south and east of Sestrière is that they don't really have a base. So you really have to wait a while during the dump before you can ride between the trees.

Should you go to the north of the Piedmont or the Dolomites instead? It will also snow heavily in those regions from Saturday to Sunday. It's already snowing southeast of the Monte Rosa since the night from Friday to Saturday. But... the temperatures will rise on Sunday. Something we see in multiple calculations. This has two causes. First, the incoming air from the south will get warmer by the hour. Second, the jetstream will postion itself for a route east of the Alps (it won't hit the southern Alps directly any more) and this will result in less orographic cooling. The result is that the Po-valley fills up with warm air and the snow line will rise steadily. In the final calculations, there is one exception on the southern side of the Alps and that will be the western and southern Piedmont. The temperature won't rise that much over there.

Jetstream for Sunday
Jetstream for Sunday

You can also see that on the maps with the temperatures. The big green spots have disappeared south of the Alps and the supplied air is warmer. With a rising snow line as a result.

The temperature will rise
The temperature will rise

The temperature will drop stronger east of the Monte Rosa, the Mont Viso and the eastern regions in the Dolomites. The temperatures will rise in the rest of the Alps, with a rising snow line south of the main Alpine ridge. It will be around 600-1000 meters in the night from Saturday to Sunday, in the course of Sunday it will rise towards 1200-1500 meters, and the snow might be wet up to 1900 meters. Exceptions are the resorts east of the Monte Rosa, the Mont Viso and the Dolomites.

Air temperature at 1400 meter
Air temperature at 1400 meter

And then there is the phenomenon of micro climates. There are valleys where the heat just can not penetrate because of the location and extent of the valley. This has to do with the fact that cold air is heavier and simply can't be blown out of the valley.

Temperature at the ground
Temperature at the ground

This can be seen in the so-called 'inner-alpine valleys' in the French Haute Maurine and the Haute Tarentaise on Sunday. It will also remain pretty cold in the small valleys in Valais (Haute Valais to be precise), like the southern valleys of Saas Fee and the areas at the Simplon. And do not forget about the Italian Ortler. Even on the Italian side of the Mont Blanc it will be pretty cold. This will give you plenty of options where it will snow heavily and the temperatures won't rise that much. Sunday will be a great day to ride powder between the trees. Don't forget to have a look at these three things:

  • Is there a base?
  • Are the lifts open?
  • What's the avalanche danger?

PowderAdvice on Saturday and Sunday

There's not much of a base in the western and southern Piedmont. It will definitely have to snow one night before you can ride in the trees. That situation is better around the Monte Rosa and the Mont Blanc. But... it won't snow that much around the Mont Blanc (in resorts such as La Thuile or Courmayeur) the next 24 hours. You can ride some powder around the Simplon and Monte Rosa on Saturday (Saas Almagell just south of Saas Fee is a secret). You can also ride powder around Alagna and Gressoney, and in the Milky Way. We recommend you to ride powder on the slopes. Although the snowpack in the Milky Way will grow rapidly on Saturday afternoon.

You'll have more options on Sunday. It's snowing intense from Saturday to Sunday and a second front arrives on Sunday afternoon which will result in higher temperatures. The snow line will rise to 1000-1400 meters. It will snow heavily in the eastern Dolomites and the entire Piedmont especially in the night from Sunday to Monday. Tree Runs are a must!! Don't go into the alpine. The tips for Sunday:

Snowfall in the northern Alps on Monday

More snowfall in the Piedmont in the night from Sunday to Monday. It stays cold and Monday morning will be quite good in the Piedmont. The current will move to the north-northeast thanks to two low pressure areas (one above Italy and one east of the Alps).

Current to northeast
Current to northeast

You can see in the Föhn diagram that the temperature will rise in the southern Alps. The temperatures will drop on the north side of the Alps and it will start snowing. It will snow heavily especially in the Swiss Bernese Oberland. This means you can pack your bags on Monday and drive to the north side of the Alps where we can get ready for PowderAlert #11.

Cold temperatures in the north, high temperaturs in the south
Cold temperatures in the north, high temperaturs in the south

This will be the chase the next couple of days:

  • To the Piedmont on Friday
  • Freshies in the Piedmont and the southern valleys in Haute-Valais on Saturday
  • It will be ON on Sunday in the resorts listed in the PowderAdvice
  • The Piedmonte will be good on Monday and than north for PA #11!

If you want to book your accommodation: support wePowder and use this link.

Stay stoked!
Morris

Comments


  • 8611
    Tourist
    8611 op 26 February 2016 · 18:50
    Very detailed and thought out report Morris, thank you for posting, good luck to anyone chasing the conditions this weekend
  • meteomorris
    Tourist
    meteomorris op 26 February 2016 · 22:05
    @8611 Thank you!!
    May the powder be with you.
  • DWF
    Advanced
    DWF op 27 February 2016 · 09:11
    I drove from Zurich to Briancon yesterday passing Susa - Olux - Montgenevre at midnight and only significant snow was falling in Andermatt.

    Abries is totally with out base and it looks like its raining now....

    Sestriere looks windy but not a lot of snow.

    Lets hope it starts to snow. Alagna might be good if they can stay open.
    DWF
  • Fabi
    Tourist
    Fabi op 27 February 2016 · 10:30
    Thank you for your report Morris. We are thinking of Rothwald for tomorrow any thoughts on our plans would be greatly appreciated !
  • Powdernick
    Advanced
    Powdernick op 27 February 2016 · 14:27
    Has any one any idea about mondolo in Italy, looks like its getting a ton of snow today. Otherwise heading to Limone.
    Ski ya later.
  • Rickyiy
    Rickyiy op 28 February 2016 · 00:04
    Hey Morris thx for info. I got a question: i thought precipitation and energy loss leads to rising tempereatures?

    Thank you

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