First two snow events, then calm again due to increasing high pressure


By Henri on 4 February 2022 · 5

Sunny start of the day in Arosa (roundshot.com)
Sunny start of the day in Arosa (roundshot.com)

After an stormy week with a lot of snow, calm has temporarily returned. Yesterday it slowly cleared up, although it was still cloudy in many places due to the western flow. Today will be sunny for most areas in the Alps. Later today, new clouds will follow from the northwest as a result of an approaching cold front. Until Monday, the Alps will have to deal with two moments of snow, of which the second one will be the most. After that, the calm high-pressure conditions seem to return for a few days.

In this weather report:

  • Loads of snow
  • Temporary sunny
  • Snow in Western Norway
  • Two snow moments for the Alps
  • Then calm and sunny

Lots of snow

The weather forecasts on wePowder are powderded by our friends from Ortovox

A lot of snow fell in a short time from Monday to Wednesday. Up to one metre of snow fell in higher altitudes. On the Nordkette near Innsbruck, you can see that the snow level rose from 120 to 250 centimetres within a few days. In combination with the strong wind, this snow caused a high avalanche risk. Due to rising temperatures on Wednesday, the snow unfortunately turned into rain in lower areas. The snowline rose faster and earlier than expected due to the strong winds. Just above the snowline, the snow became unfortunately heavier and heavier, making the fresh layer of powder a lot denser.

More than a meter of snow on the Nordkette (wiski.tirol.gv.at)
More than a meter of snow on the Nordkette (wiski.tirol.gv.at)

Temporarily sunny

Today will be a beautiful day with lots of sunshine in many places. Especially with the nice weather, many people will go out, but there is still a high avalanche risk. In Tirol alone, 26 avalanches came down yesterday. So keep a close eye on the avalanche reports.

Today we are temporarily in the warm sector of the low pressure system in front of the Norwegian coast, which makes it quite mild, especially higher up. In Norway, this weather situation could lead to a lot of snowfall in the coming week. The jet stream is aimed right at the mountains here, which means that the constant input of moisture will bring a lot of snow to the west of the country.

A lot of precipitation in the next days in Norway (wxcharts.com)
A lot of precipitation in the next days in Norway (wxcharts.com)
Cold front approaching this evening (wetter3.de, DWD)
Cold front approaching this evening (wetter3.de, DWD)

Cold front from the northwest

But also in the Alps it will start snowing again. Around midnight, a cold front will reach the Alps from the northwest. The front is quite weak, so we should expect little fresh snow. It will give a dusting of snow on the northern side of the Alps, with only between Central Switzerland and Vorarlberg 5 to 10 centimetres of snow with a snowline that drops from 1000 metres back to 500 to 700 metres. Saturday will be sunny again due to temporary increasing high pressure from the west.

So the first snowfall won't give that much. We should focus more on the snow that will fall from Sunday evening onwards. The high-pressure influence will decrease more and more during the course of Sunday, and from the north-west it will start snowing again, probably a lot more this time. Most weather models predict 20 to 50 centimetres of snow for the northern regions in Austria and Switzerland. The French Northern Alps will probably get less with 10 to 30 centimetres. Again, this snow is falling with a very powerful north-westerly flow, which means that it's going to be quite windy up there.

Expected snowfall in the next six days
Expected snowfall in the next six days

A point of attention is the snowline, because a portion of mild air is also advected from the west. Initially, the snowline will be around 1200 to 1500 metres due to the expected stormy winds. During the night from Sunday to Monday, colder air will enter from the north again, which will cause the snowline to drop everywhere. From the west it clears up quickly on Monday, but in Austria it may continue snowing a bit longer with a snowline down to most valleys. As usual, the southern Alps will hardly notice anything of this snowfall from the northwest, but on Monday morning some 5 to 10 centimetres of snow could fall in the northern areas because the snowfall could reach over the alpine ridge.

On Monday, it will slowly but surely clear up from the west. The following days seem to become sunnier due to increasing high-pressure conditions. By the end of the week, the Northern Alps are likely to receive again some fresh snow.

Comments


  • childrenanddogs
    childrenanddogs op 4 February 2022 · 23:59
    Is there any sign of more than a dusting of snow in the Southern Alps? It’s been so dry for weeks and weeks, we’re heading to Sestriere on the 20th but I’m starting to wonder if it will be a walking holiday at this rate……any hope of a decent amount of snow before then?’
  • Henri
    Beginner
    Henri op 5 February 2022 · 09:31
    @childrenanddogs not yet. Next week will be dry as well and also after that we still cannot see any signs of some serious snowfall..
  • rich_a_potter
    Tourist
    rich_a_potter op 5 February 2022 · 11:19
    @henri, worrying information I suspect driven by our warming climate. For the uninitiated in climate modelling, can you explain the above diagram ( the p1 p2 p3 lines and the Ens mean ) - are the "p's" various climate models and the Ens mean is an average of them all?
  • Henri
    Beginner
    Henri op 5 February 2022 · 12:33
    @rich_a_potter I'll write an article about how to interpret these weather charts, also this ensemble. First I have to say this graph is about the weather (for this case in Turin, Italy), not the climate! It's a ensemble forecast of the GFS model with temperature at 850 hPa (roughly 1500 metres altitude) and the precipitation. The red line gives the climatological mean of the temperature of the time period 1981 to 2010, so you can get a rough idea what normal values for this time of the year are.

    Basically, an ensemble like this tells you a lot about the (un)certainty of a forecast. All you need to know for now: at first, all the members are fairly close to each other, so it's fairly certain this situation is going to happen. On Monday (7th of February) for example, the temperature will decrease due to the northerly flow, but will increase soon after as you can also see in this graph. All lines follow this pattern more or less. But if we move further to the right (later next week), the spread between the individual members is increasing, so it's getting more and more uncertain what will happen. If you have a look at the end of the graph, we see a hugh spread between the members and it looks chaotic. So, it's almost impossible to say something about the weather in two weeks for this region. At the bottom of the graph you can see the precipitation. Almost all runs are calculating basically no precipitation in the next week. Only on Monday some precipitation from the north may reach the southern Alps as I explained in the weather forecast.

    The green line is the main run so to say, blue is the control run uses the same initial conditions as the main run, but on a coarser resolution. Then, all individual members p1-p30 have slightly perturbed initial conditions (a bit difficult to understand why we need to do this, but I'll explain this in my article), which lead to different calculations. These calculations are also with a coarser resolution, because there is a limited amount of time for the supercomputers to calculate. It would otherwise cost way too much computing power to calculate all these members. There is much more to say about these interesting graphs, but I'll explain that in a seperate article.
  • rich_a_potter
    Tourist
    rich_a_potter op 9 February 2022 · 09:36
    thanks @henri , interesting stuff ! 😃

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