Snow for the French northern Alps? Or not?


Par meteomorris sur 25 octobre 2017 · 0

The next couple of days will be exciting. There is a battle in the atmosphere going on between cold air from the north and warm air from the south. The biggest blockade for the cold, polar air from the north is a high pressure area called Ulrike. This vast high pressure area is still above the Alps right now and is pushed somewhat westwards the next couple of days. The big question is how far? A simple question you would say, but the reality is different. A shift of a few hundred kilometers to the east or west can be the difference between a big dump or just a few flakes.

The next couple of days will be exciting and the outcome is not yet predictable. The consequences for the French northern Alps and Switzerland can be pretty big. Because Austria is further to the east, the chances for snow are the biggest and most certain over there. In this forecast:

  • It starts to look like winter in the northern Alps
  • Still no flake at all in the southern Alps and large parts of the French Alps and Italy
  • Northern Stau this weekend
  • Where will the snow fall?

((c) foto-webcam.eu)
((c) foto-webcam.eu)

It starts to look like winter in the northern Alps

The above picture is from this morning. It was taken at the Rudolfshütte at the Weissee Gletscherwelt at an altitude of 2300 meters. The contrast between the white snow and the lake is beautiful. It shows the transition from autumn to winter. The water still needs to cool down, while the atmosphere is getting in shape for winter. Last weekend's snow gave the high alpine a white character and is the base for the winter on the glaciers and north faces. The conditions on the glaciers in the Alps are quite okay right now and it's really good on the glaciers in Austria. Check out the images from yesterday.

TIP: The lifts are already running in these ski areas

Still no flake at all in the southern Alps and large parts of the French Alps and Italy

It may be been winter in parts of the northern Alps, in still as dry as possible in large parts of the French Alps and Italy. Exception is the Stelvio Pass, where the glacier always picks up some snow, but it is still not much. That has everything to do with the pressure distribution. There hasn't been any major atlantic depressions that arrived in the Alps from the west and we haven't seen a single Genua-low. But to be honest, that's no big deal. The best dumps for the south side of the Alps start from mid-November and can result in a snowpack of a couple of meters in just a couple of weeks. My hopes are on such a scenario. Thick dumps are much better for the stability of the snowpack and snowfall in October is just too early for the southern Alps. In short, do not let the images below frighten you. The snow comes when it comes.

Northern Stau this weekend

There is no snow on the maps for the French southern Alps and Italy at the moment. But that is different for the north side of the Alps. High pressure area Ulrike is moving west the next 96 hours and will open the door for cold air from the north. Check it out on the video below.

The main question is, as I said before, "where will this high-pressure area end up?" It was calculated a bit further west yesterday compared to today and you see the difference on the snow maps. Check out the runs below from yesterday and today. The big difference is that on yesterday's run there is still snow forecasted for the French northern Alps, but not on the run today. That has everything to do with the high-pressure area. At high pressure the air drops and precipitation resolves. The closer the high pressure area sticks to the Alps, the lesser it's likely to snow.

So that will be the question the next couple of days. The snow is forecasted for the weekend and that means a forecast is never 100% reliable. So expect the snow maps to change the next couple of days. This is my rule of thumb for the snow maps:

  • 12 hours in the future: 80-90% of all the cases are correct
  • 48 hours in the future: 70-85% is correct
  • Up to 120 hours in the future: 50-75% is correct
  • Up to 144 hours and further in the future: 45-55% of all the cases are correct

The diminishing reliability is the result of the noise in our global observations and forms the basis for the chaos theory. Nevertheless, I am always looking forward to detailed long-term forecasts. Thanks to the differences per day you can see the fluctuations and you'll get a nice feeling of the overall picture. And that picture is simple for now. A strong current from the north is getting started between the high Ulrike and the storm Floren This current will bring cold air to the north side of the Alps. This will result in snowfall on the north side of the main alpine ridge, while the areas south of the main alpine ridge will have to deal with sunshine and warm winds.

Where will the snow fall?

I'm sure that (parts of) Austria will get a lot of snow from the north. There is a good chance for Switzerland, especially for the resorts in the east. The resorts in the west, but also in the south and in the main alpine ridge will see much less or even no snow. I'm not optimistic for the French northern Alps. The last four runs show less and less snow for France.

Stay stoked Morris


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