It's snowing! Another dump this weekend?


By meteomorris on 23 October 2017 · 6

It's been snowing in the Alps since Sunday. There were some heavy winds in the high alpine when it started snowing, but thanks to a high-pressure area that's gaining ground from the west the wind won't be that strong anymore, which allows the snow to actually stay where it came down. You don't have to expect any precipitation in the Alps tomorrow. That will be temporarily, because new depressions are ready to send some storms to the Alps. In this forecast:

  • Up to 30 cm of fresh snow already
  • No precipitation the next couple of days
  • New storm depression this weekend

Up to 30 cm of fresh snow already

Between 5-30 cm of fresh snow has fallen on the north side of the Alps since Sunday and parts of the northern Swiss alpine ridge already got 50 cm and more. That has already resulted in some nice images and it is still snowing. The measuring stations now begin to show nice numbers, with numbers that are close to the 40-50 cm. It is important that you realize that the amount of snow that comes down and the amount of snow that eventually lies on the ground is not the same. Please read this article again.

You can easily find these measuring stations near a ski area on the new wepowder website. On the page of a ski area (for example, Glacier 3000) you will find a list of measuring and weather stations in the right column. Ideal to check the conditions. The figures from the measuring stations will increase even further today. It will keep on snowing until Tuesday morning. After that, high pressure will take over.

No precipitation the next couple of days

High pressure will take over from Tuesday. Warm air from the south arrives in the Alps and it just gets very warm again. Some residual clouds will remain in the valleys, but it's just dry and warm at the peaks. As a consequence, the snow that came down today and yesterday again will melt at low altitude. The high alpine still profits from the current snowfall. Fortunately, there is snow in the forecast again.

New storm depression this weekend

There's a new storm depression visible on the maps this weekend. High pressure is still around, but that's mostly calculated for the west and that means a free passage for a current from the north to the north side of the main alpine ridge. According to the latest calculations, the models agree that this attack with cold air will actually happen. The most important weather models models also calculate a drop in temperature drop from this weekend, with increasing precipitation.

The above plume of the ECMWF and GFS show the temperature peak, but also the drop in temperature. In addition, precipitation is calculated. Something that is very similar to our own model. There are some nice colors visible on the maps.

Stay stoked Morris

Comments


  • AdamStekl
    Advanced
    AdamStekl op 24 October 2017 · 15:06
    Hi wepowder team,
    the new website have great improvements. Good job!
    I will definitely buy the pro version.
    Adam
  • meteomorris
    Expert
    meteomorris op 24 October 2017 · 15:18
    @AdamStekl thank you!!!
    May the powder be with you.
  • arslonga
    Advanced
    arslonga op 24 October 2017 · 22:28
    115 cm in fiesch? don't you think that snowfalls are heavily overestimated?

    non rompete il c**** al cavaliere nero....
  • meteomorris
    Expert
    meteomorris op 25 October 2017 · 07:42
    @arslonga You could be definitely right. The 115 cm is mostly predicted for Sunday which is 6 days in the future.
    My rule of thumb is: predicted snowfalls are 80-90% correct 12 hours before they actually arrive, predicted snowfalls are 70-85% correct 48 hours before they actually arrive, predicted snowfalls are 50-75% correct 120 hours before they actually arrive and predicted snowfalls are 45-55% correct 144 hours before they actually arrive. In my opinion long term predictions can function as a guide if there is a chance on any snow, but not as a certainty that the predicted amount will fall. I would advice you to do the same.

    Sometimes amounts are over estimated by the models, sometimes they are underestimated. Especially during the autumn period there is a lot uf dynamics going on in the upper air layers (and in the weather models). We have seen huge dumps during these period, but also overestimated predicted dumps. See them as a guideline to get a feeling of the weather to come and use my forecast as a side read to get a feeling.

    All models do have this problem and not even snow forecast websites. I am know a long time pro member at magicseaweed (a website for surfers (https://magicseaweed.com/pro/)) and they do have the same problem. Long term predictions always have (some) uncertainty in it. That's why they are called predictions. The further we look in the future the easier chaos can take control (https://en.wikipedia.org/wiki/Chaos_theory). But what I loved about magic seaweed that it is trying to make long term predictions in a way that normal people can understand instead of starring at complicated weather charts.

    The current wepowder website is a starts of a journey in which we try to make long term predictions better to understand. We are definitely not there where we want to be, but as long as you keep supporting us we are able to make (small) steps and improve our website.

    Hope this helps. Thanks for your feedback!
    Cheers
    May the powder be with you.
  • arslonga
    Advanced
    arslonga op 25 October 2017 · 23:19
    hi Morris

    thanks for your detailed answer. the point is that if we see 115 cm and we have 40 it seems nothing. but if the forecast is 30 cm everybody will say hallelujah! so the solution is to use "safe"(i.e. underestimated) predictions and cut them a 30%..... 😉
    cheers and #silenziogram
    non rompete il c**** al cavaliere nero....
  • meteomorris
    Expert
    meteomorris op 26 October 2017 · 11:07
    @arslonga thanks. We are finetuning our algorithms every day at the moment, but all models exaggerated their predictions the last few days as you might have noticed. Fall season is always very difficult for all the weather models as their is so much dynamics going on in the upper air levels.


    *message edited by meteomorris op 26 Oct 2017 11:07 (1% bewerkt)
    May the powder be with you.

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