Some snow for the northeast


Von meteomorris an 20 Februar 2019 · 1

The situation in the Alps remains the same with the exception of the northeast of the Alps. The Alps are under the influence of an immense high pressure area and storms are kept at a considerable distance. They move around the Alps with a large curve.

The jet stream, the guide rail for storms, now runs via Scotland, Scandinavia and the Baltic states towards Eurasia. You can see the jetstream for tomorrow below. It is the red-yellow river that marks the difference between cold air in the north and warm air in the south. And the Alps are now in the warm air. To verify this, you can find the temperature under the jet stream map at 850 hPa (say 1400 meters) in the free atmosphere. It is clearly above zero in the Alps.

Jet stream
Jet stream

Temperature at 850 hPa
Temperature at 850 hPa

It was very warm (especially the last few days) and in all avalanche forecasts they warned for wet and 'gleitschnee' avalanches. We are dealing with the first really warm period in the Alps and therefore the snow cover is put to the test. The rise in temperature causes the snow cover to warm up rapidly on sunny slopes, causing the mass to increase and a moment comes when the critical limit is reached and the snow cover starts to slide. Usually that goes by without problems, but it causes a lot of trouble in Crans Montana yesterday afternoon.

Huge avalanche Crans Montana

A huge wet snow avalanche came down on a slope at 2.30 PM. The reporting has been chaotic for a long time, initially involving 4 injured people (of which 1 person is still in danger of life at the time of writing), but also 12 people who were still stuck in the avalanche. They've been searching until Wednesday morning, but they couldn't find any more victims. Unfortunately the news came in that one of the four injured people passed away... More information here.

The footage below of a witness on the spot shows how large and immense the aerosol was when the snow mass plunged onto the slope.

Such avalanches are quite common during winter, but as a rule we only see them during the first really warm week in March and sometimes even in April. Slopes that are threatened are then closed during the day and avalanches are preventively triggered. It is extremely exceptional to experience something like this mid-February.

The temperature will drop a bit the next couple of days, but there will be an increase in the temperature after the weekend that may be even higher than the last couple of days. With peak season in the Alps this will be a point of interest for ski patrol.

Some snow for the northeast between Wednesday and Friday

The high pressure area will retreat a bit to the west in the coming days, causing the jetstream to hit northeastern Austria. At the boundary of warm and cold air clouds arise and they will be pushed against the northern Stau areas of the Salzburgerland, Styria and Ober- and Niederosterreich with a northern current. This produces 5-15 cm, locally 25 cm of snow between Wednesday and Friday. The snow line is initially around 1000 to 1300 meters and drops to 700 to 1000 meters in the course of Friday.

It can snow heavily on the peaks of the Salzburgerland, Styria and Ober- and Niederosterreich especially on Friday, but in the valleys it rains. In addition, there is a strong wind. Keep in mind that the avalanche situation is deteriorating and the danger is increasing in the regions concerned.

High pressure returns
High pressure returns

High pressure again from the weekend

The snowfall between Wednesday and Friday is the only exciting thing that will happen in the coming days. A high pressure area over Scandinavia drops towards Poland in the weekend and will reach the Alps later. According to the current calculations, it stays there for a week so the sun and blue skies will dominate.

The weekend is first and foremost pretty cold in the eastern Alps. Cooler continental air is supplied with a cold easterly current. Especially in the Piedmont this can provide some flakes. It will quickly become warmer after Monday. The temperature will rise considerably, certainly in the western Alps, but later also in the eastern Alps. Occasionally some clouds from the east, but if the high pressure area remains as now calculated the sun will dominate.

Het plan voor de komende dagen

Either you go towards the east where some fresh snow falls between Wednesday and Thursday, or you go for a wonderful tour in those parts of the Alps where the sun is shining. You can find more than enough on steep northern faces. Snowboard guide Irian van Helfteren knows his way in the Arlberg and he still rides cold powder every day.

In addition, northern faces are now in shape for the steeper work. The snow cover is very stable everywhere and as long as the sun can not reach those faces, it stays that way. You can ride more and more beautiful alpine lines now that the visibility is good and the snow is nice. But stay away from sunny slopes because of the rapid warming, the situation is much more unstable now.

Again my words from last week:

Put an ice cream on a dry day in the sun and it melts quickly, put an ice in the shadow and it takes much longer. Put that same ice cream on a layer of snow in the shade and you will see that it takes even longer before the it melts. This also applies in the mountains. In fact, put an ice cream on a snowy shadow slope in the middle of the winter and you will see that the ice cream does not melt. Even if the temperature in the free atmosphere is clearly in the plus and people are relaxing in the sun.

It works like this. The snow cover itself is not directly susceptible to changes in the air temperature due to the insulating capacities of the snow cover. For warming the snow cover, the following three elements are the most powerful:

  • Direct radiation of the sun
  • Relatively warm air and clouds. This is because the clouds conduct the warmer, humid air into the snow cover
  • Rain

The sun is lower in the winter. The result is that it only directly affects the southern slopes and the steeper western and eastern slopes. On the other slopes, the sun is at most gently touching the snow cover and as a result the warm air can not penetrate the snow cover. As a result, the temperature of the snow cover on more shady slopes, but also those slopes where the sun does not directly hit, remains considerably lower. Often even well below zero. Especially when the nights are clear and the moisture can radiate considerably. Days on which you can see nice amounts of surface hoar on the snow cover on the shadow slopes.

Surface hoar
Surface hoar

Warm but sunny days do not mean that this is the end of the fresh powder snow. You just have to work a bit more for it. It is only mid February and the sun is still relatively low. This means that on slopes with an N, O or NW component you can still ride powder for a while. Especially when there are also trees on these kind of faces, then the sun does not hit the snow cover at all.

But how do you know if a ski area has enough N, O or NW slopes? You can check that out yourself with a compass, but you can also take a look at the exposition maps when you are a wePowder Pro. Below you can see the map of the Tannheimertal as an example.

The red colors on the map indicate the Northern and Northeastern slopes and if they are a bit steep, the snow stays good, light and fresh.

As wePowder Pro you get access to exposition, freeride routes, slope angle maps and the 14-day forecast per resorts (we've got all the resorts in the Alps covered). You never have to miss a dump anymore. When you are wePowder Pro you also have access to 1000+ inspirational freeride routes in the most beautiful freeride areas of the Alps. Sign up as wePowder Pro today. It works great for your karma as well and you'll support the development of the wePowder platform! Thanks!

If you want to ride powder in the coming days, then you should search for:

  1. ski areas with plenyty of northern slopes where the powder remains cold enough;
  2. and look for family areas with lots of trees and little obvious terrain, that scares beginning freeriders.
  3. and delete the usual suspects and areas with a lot of easy access terrain.

With these tips you will certainly find some fresh powder.

Stay stoked, Morris

Kommentare


  • Chester_Tartsnatcher
    Expert
    Chester_Tartsnatcher op 21 Februar 2019 · 16:29
    I hope this high pressure breaks before March 7.

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