PA #7: Battle of the weather models


By meteomorris on 20 January 2017 · 4

It's bluebird in the Alps and the countdown for PowderAlert #7 has begun. The conditions in a lot of regions in the Alps have improved. And there's snow in the forecast for the Piedmont. The weather is great in the Alps, but it can't get worse in central Italy where an avalanche hit an hotel in the Abruzzo, killing lots of people... Our thoughts are with their families and friends. Meanwhile, Austria got their share of avalanches. Four people were killed by avalanches in western Austria last week. There's an old and weak layer in the snow cover in lots of places in the northern Alps that's the perfect sliding layer for avalanches. This weak layer can't be recognized with the naked eye and is therefore invisible, even for experts. You'd better adapt your riding to it!

TIP: check the avalanche forecast on the resort pages on wePowder or lawinen.org

Because the snow cover in still relatively thin in lots of places, the weight of a single skier or snowboarder can already be enough to disturb the balance in the snow cover and trigger an avalanche. We'll have to wait till the next dump before this old layer will be even deeper in the snow cover and won't form that much of a thread anymore. But there's no significant snowfall in the forecast next week, so you'd better ride very defensive or below 1900 meters. In this forecast:

  • Genoa low in the forecast
  • No precipitation in the west and north of the Alps
  • What will the long term bring?

Genua low coming up!
Genua low coming up!

Genoa low in the forecast

A classic Genoa low in the making over the Mediterranean. It will travel to the Italian Piedmont and the Po-valley from Saturday and this will result in snowfall for the Piedmont. The weather models don't exactly agree on the amounts of snow. The European model is less positive than the American model, so the expected amounts of snow can sometimes differ more than 50 cm until Tuesday.

GFS expects 91 cm in the Piedmont
GFS expects 91 cm in the Piedmont

ECMWF expects 30 cm in the Piedmont
ECMWF expects 30 cm in the Piedmont

It's a classic battle of the models. Looking at the air pressure maps of Sunday and Monday, you can see that Hirlam and GFS pretty much agree, which means the American model could be right. That would be positive for the forecasted snow. I'll post my updates on the forecasted snow in the comments of this forecast the next 48 hours. For now, I agree with the American model. The current, low temperatures, the relatively warm water in the Mediterrenean and the typical terrain of the southern Alps are factors that I'm pretty positive about the forecasted snow in the Piedmont.

PowderAlert #7 is on for the southern and western Piedmont and I am also positive about the eastern resorts of the Monte Rosa. Anyway, more details the next 48 hours. Stay tuned!

No precipitation in the west and north of the Alps

Low pressure in the Mediterranean Sea and high pressure north of the Alps means that it's impossible for storms to reach the northern and western Alps when the current comes from the east to northeast. The result is that it will be dry and sunny. In addition, it's relatively cold, even though the air in the upper layers of the atmosphere is warming up in the next 96 hours. The result is that the inversion will get stronger. Cold air (but also polluted air) will stick around in the valleys. For sun, milder temperatures and cleaner air you'd better go up the mountain!

What will the long term bring?

You can expect this kind of weather until the last week of January. This means that the storms will be kept at a distanc. There's only a chance of snow for the southern Alps and in particular the Piedmont.

Stay stoked. Morris

Comments


  • meteomorris
    Tourist
    meteomorris op 20 January 2017 · 19:01
    GFS remains positive..



    And according to the Kuchera Algorithm even more

    May the powder be with you.
  • meteomorris
    Tourist
    meteomorris op 21 January 2017 · 10:08
    The high pressure area over Europe is not willing to allow the storm track into NW Italy. Although the calculations of yesterday (and the last days) were in favor of a strong eastern flow in the Po valley, the calculations point this strong flow today just below the Po-Valley. In consequence there is a lot of snow in the Forecast for Sardinia but way less for the Piemonte. (blue line).

    There is some moisture within the Po-valley but with a ta relatively weak northeasterly flow this is only focused at the southernmost part of Piemonte (green arrow).



    The high pressure area is to strong at the moment.
    May the powder be with you.
  • Bjarmann
    Advanced
    Bjarmann op 22 January 2017 · 22:27
    Which resorts in the Pyrenees do you recommend for the next days? Wednesday and Thursday.
  • meteomorris
    Tourist
    meteomorris op 22 January 2017 · 23:27
    @Bjarmann the most eastern resorts. Not that steep but fresh snow though
    May the powder be with you.

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