PA # 7: shifting sweet spots, half a meter + possible?


Door meteomorris op 15 januari 2020 · 4

Anyone who wants to chase powder in the Alps this January 2020 must have a strong heart and a lot of patience. After an almost endless dry spell a storm finally pops on the radar and even then your patience is tested to the maximum. For the fifth day in a row, the models come with an adjustment to their calculations and again the sweet spots with the most forecasted precipitation has moved to another part of the Alps. In this article:

  • Is there something the weather wants to make clear to us?
  • Friday-Saturday-Sunday-Monday: the new storm
  • Cold on old: is it going to be deep enough?
  • Very high risk of storm slabs (= avalanches)
  • What has changed compared to yesterday (blower pow pre-warning)
  • PA#7: the northern Alps east?

Is there something the weather wants to make clear to us?

In large parts of the European mountains it is too mild and certainly the lower and middle range mountains suffer from a huge lack of snow. We have been dealing with a mild southwestern airflow for weeks. Since the low-pressure areas currently circle mianly around the North Pole, high-pressure areas hold their grip on central Europe. [December was way too mild](https://www.meteoschweiz.admin.ch/home/aktuell/meteoschweiz-blog.subpage.html/de/data/blogs/2019/12/klima-monat-dezember.html ) in the Alps and January is on course to be also way too mild. Today is no different with temperatures that are locally 10 degrees above the long-term average. (source)

And for those who think that this 'heat wave' is only affecting Europe is wrong. The entire Northern Hemisphere is today 1.1 degrees Celsius warmer than normal. (source).

With such mild temperatures, snow cannons in the lower mountain ranges of Europe are not able to produce artificial snow. In Gerardmer in the Vosges, the piste bullies are waiting for better times.

If we did'n had the snowy SNOWvember month in the Alps, the situation might have been dramatic. The current situation is strongly reminiscent of the start of winter 2015. A strong Polar Vortex then also dominated the weather in central Europe, which came to an end after almost 2 months. So the storm that managed to slip through the band of high pressure this weekend may be small in size but the snow she brings is more than welcome and who knows it may be the prelude to a colder or at least cooler period for the Alps.

Below is a brief summary of yesterday. If you scroll directly down, you can read what has changed compared to yesterday.

THE TEXT BELOW THE LINE IS A COPY OF YESTERDAY's - JUMP DOWN TO THE NEXT STRIP FOR THE (GOOD) NEWS


Friday-Saturday-Sunday-Monday: the new storm

It is clear that a storm is tracking towards the Alps. But the details vary continuously. It is not without reason that I am reluctant to launch a powder alert and wait until all details are clear and that has three reasons:

  1. How much is going to fall exactly where
  2. cold on old: does it get deep enough
  3. very high risk of storm slabs (= avalanches)

  4. Where will the sweetspot be? How much to expect?
  5. Cold on old: does it get deep enough
  6. High risk of storm slabs (= avalanches)

Which doesn't mean that you can ride powder this weekend and the days after. But choosing your destination too fast can result in dust on crust. Which would be a shame.

Where will the sweetspot be? How much to expect?

The jet stream is the engine behind the snow this weekend, but it staggers above the Alps and loses its power there. That makes it difficult for me and for the models. The most logical forecast would be a front that goes into the Alps on Friday from the west. First of all, the current is southwest, which immediately turns to northwest when the cold sector is moving in. Most snow then in the northwest of the Alps. At the same time, a Genoa storm will be created south of the Alps. Which means that the upper air flow will turn from southwest to northwest to northeast to east. This Genua storm in particular makes it incredibly complex. We are now at least 96 hours before this event will take place and therefore it is wise to hold your horses Yes, it is going to snow in the Alps and yes there are significant amounts of snow in the air. But where exactly how much? I'll come back on this later. For the time being, I assume 20-40 cm in the northwest and north, with possibly significant higher accumulations in the western and southern Piedmont.

Cold on old: is it going to be deep enough?

Then there is this second problem. In the best case there will be 20-40 cm of fresh snow and maybe even more in the Piedmont. But the storm for the Piedmont is expected to arrive Sunday-Monday and that is just too late for many because Monday will be the start of another working week. Then move to the north and northwest? The quantities and exact locations are not yet certain and in this case the what I call: cold on old snow plays a major role. The cold snow that will fall on Saturday will fall on an old, often hard and wind battered snow layer. In such a case you need at least 25 to 40 cm of fresh snow to make sure that you track your lines without hitting the old snow layer. So only the sweetspots that will get the biggest accumulations will get enough fresh snow to make it deep enough.

High risk of storm slabs (= avalanches)

Conclusion: it can still go either way. That a storm will follow, that it will be colder and that snow will follow, can now be said with certainty. But where you want to be when the upcoming storm is far from saying. In short, hold your horses. And again when the snow starts falling, a warning is in place:

Fresh snow is on its and this will surely cause a lot of powder pabic. But fresh snow on an old snow layer also guarantees problems. In case of new snow, take a rapidly rising avalanche danger into account. Especially storm slabs will be a problem. To prepare yourself already, it might be a good idea to refresh your knowledge with our Mountain Academy.

BELOW THE NEWS BEGINS ...


The changes from yesterday

So far a copy of yesterday. What has changed?

Negative changes

  • The front that tracks towards the Alps from the northwest on Friday-Saturday is less powerful than previously calculated. As a result he precipitation amounts for the western Alps and the northern Alps west (see also your wePowder Guide for all the details about these regions) are lower than previously calculated.
  • The Genoa storm that occurs after the front has tracked into the Alps is much less powerful in the current most recent calculations and will also track to the southeast more quickly than in earlier calculations. The chances of a strong Retour d'est are therefore rapidly reducing since the storm is too short in the right position and has too little force because the air pressure is higher than calculated.

Positive changes

  • Due to the rapid tracking of the Genoa Storm to the southeast and the quikly rising high-pressure area, a north-eastern airflow is created north of the Alps. As a result the moisture that moved into the Alps from the west on Friday-Saturday cannot escape to the east and is stuck and pushed againt Austria's pre-Alps. You can see that clearly on the weather map above. Since the air is very mild at first (it is now still +10 at 1500 meters) and the fact that the temperatures will drop rapidly this weekend (-10 at 1500 meters) there is a lot of moisture in the air that will be mixed with very cold air. This usually produces very dry blower pow. In such a situation a mm of moisture can sometimes produce 1.5 to 2 cm of fresh snow. If so the conditions are here for powder alert#7 whereby I do not exclude local surprises with a lot of snow.

This event might take place in the pre-Alps of the Northern Alps Central and the pre-Alps of the Northern Alps East in terms of your wePowder Guide.

Provisional conclusions:

  • mild and sunny until Thursday
  • a storm from Friday and Saturday
  • Saturday - Sunday intense snowfall in northern Alps east? (blower pow pre-warning)
  • please note: increased avalanche risk

A further update tomorrow. But it seems that you have to be in the pre-Alps of the northern Alps east on Sunday-Monday.

Last but not least, I want to ask you to read and where possible support Erik Bulckens' dream. Erik Bulckens is a cinematographer, documentary maker and powder fanatic. Thanks to wePowder, he has been scoring powder for years. His dream is to make a movie documentary about the people behind wePowder. For that, Erik needs your help. You can read all about it here: read here. Do you help Erik make his dream come true? Thank you very much for your help!

Morris

Reacties


  • meteomorris
    Expert
    meteomorris op 15 januari 2020 · 20:04
    It's all going to be very exciting ... and the outcome is still not written in the stars.
    A little bit of snow dancing might help!
    May the powder be with you.
  • martinsalem
    Advanced
    martinsalem op 15 januari 2020 · 20:42
    Thanks. Was thinking of pulling the trigger on a strike mission to visit a friend in Chamonix. But I think I will wait and see...
    bericht aangepast door martinsalem op 15 jan 2020 20:42 (2% bewerkt)
  • meteomorris
    Expert
    meteomorris op 16 januari 2020 · 09:31
    @martinsalem looks like cham will get some from friday to saturday. Also the Aravis range will get some which might be enough to do some touring in the backcountry.
    May the powder be with you.
  • Vertti83
    Vertti83 op 16 januari 2020 · 14:26
    Travelling to Milan on saturday for a couple of weeks ski trip, and wondering where to go from there.

    One thing I'm puzzled about, is that how significant difference there is in the base snow conditions between different areas. Basically so, that if some places get good snowfall now, is it going to be any good if there is no proper base below the new snow...? Some wise words where to find good combination of old base + new snow..? Or which areas to avoid(due to poor/missing base)..?

    BR
    - S

    PS. Thanks for the awesome site and great reports!

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