Unsettled weather and plenty of snowfall in the Northern French Alps next week !

After a mild sunny start to the current week, it’s now back to winter with a vengeance! From Tuesday night, we had another period of extremely stormy weather, with howling NW winds and snowfall and much lower temperatures. 198 km/hr gusts were recorded at the Pissaillas glacier above Le Fornet (Val d’Isère) on Wednesday afternoon!

After Thursday’s snowfall, things we have a sunny Friday morning and avalanche danger rating 4 with fresh wind blown snow on all aspects. meaning it is easy for a skier to trigger an avalanche on all aspects and over the weekend before it gets very unsettled again from Monday to the rest of next week. A lot more snow is on its way!

Off-piste skiing conditions are very varied at the moment, largely due to the wind. Snow’s been blown all over the mountain, causing some deep drifting to occur, and some very bare areas where the snow’s been scoured off altogether. Despite poor visibility and strong winds, thanks to lower temperatures and fresh snow, we advise you to wrap up warm and get out there. There are some fantastic fresh light powder snow conditions to be found if you brave the elements!

With more fresh snow expected next week, we’re looking forward to some fantastic off-piste skiing conditions, although we’ll be choosing our low slope angles, <30° (the steepest part of a red run) to start with, and keeping a wary eye out for any signs of recent avalanche activity.

Off-piste snow depths for the Haute Tarentaise 26 Feb 2020 by Météo-France

Recent history of the snowpack

Before recent snow storms the snowpack had become extremely stable, certainly up to 2500 m or so. This settling was because of the warm weather and rain humidifying the snowpack, followed by its subsequent refreezing and becoming very solid. Some days the avalanche danger rating had even been down to a 1/5.

Check out what the avalanche danger ratings mean.

However, now with all the new snowfall, and more expected next week, we will be seeing increased avalanche activity.

What is the current avalanche risk in the Northern French Alps/Savoie?

As we write, the avalanche risk is currently 4/5.

Avalanche activity is very likely both spontaneous and skier triggered. This will be true with each fresh snowfall

For any specific points about snow stability, you need to check the daily avalanche bulletins, particularly when any fresh snow comes.

Where is most at risk at the moment?

Steep slopes with terrain traps beneath them are always going to be particularly at risk.

When we receive 75 cm to a metre of new snow (which can also mean accumulations of wind-transported snow), this can produce some very large avalanches due to the increasing weight of snow (‘load’ in scientific terminology) pushing through to old instability in the form of some isolated old weak layers which still exist, especially in areas above 2500 m.

However, as we write, this is all speculation. The best way for you to keep track of snow stability (which is even difficult for the experts) is to look out for evidence of avalanche activity. Alain Duclos, the expert who advises the professionals, says that the best way to follow avalanche danger is to follow recent avalanche activity.

How does the forecast look for the coming week?

Becoming veiled, sometimes covered
This morning: generally clear sky with some residual clouds in the massifs which dissipate quickly. High clouds begin to gain from the west during the morning.
This afternoon: the sky is more clearly veiled, becoming covered in high clouds. In the mountains, a white day effect with a few possible flakes towards the summits or even locally in high valleys (where they remain anecdotal). Over the more spared Haute-Maurienne, the cloudy sky can remain brighter.

Maximum temperatures: + 12 ° C in Montmélian, + 11 ° C in Chambéry, + 8 ° C in Bourg-Saint-Maurice, + 5 ° C in Modane and + 2 ° C in Val d’Isère.

Isotherm 0 ° C: 1200/1400 m this morning, increasing towards 2100/2300 m at the end of the day.
Isothermal -10 ° C: 3500 m this morning, up to 4200 m this evening.
Wind at 2000 m: light North then West 10/20 km / h (temporarily 30/50 km / h by acceleration in the Maurienne valley).
Wind at 3000 m: North-West 40/60 km / h (temporarily 70 km / h in Haute-Maurienne this morning), weakening and tilting West at the end of the day and evening.

Loaded in high clouds
Many high cloudy periods, often quite dense (cloudy overcast), temporarily thinner. A few snowflakes spin on the highest peaks. In the second part of the night, Foehn and Lombarde resume service in their field, associated with a strengthening of the South-South-West wind at altitude.
Minimum temperatures: 0 to + 3 ° C in the plains and valleys, -2 to + 1 ° C around 1500 m.

Fairly strong southwest wind at high altitude, deterioration in the afternoon
In the morning: cloudy sky becoming overcast with the hours, with a noticeable south to southwest wind, becoming quite strong from the first heights (Lombarde and Foehn in their field).
Afternoon and evening: Covered, in the mountains. Precipitation starting on the neighboring peaks of Italy, generalizing throughout the afternoon to the whole department. They are generally weak, but may be temporarily more marked towards the Avant-Pays, the Bauges and the Beaufortain. Rain / snow limit 1600/1800 m in the afternoon, falling towards 1300/1400 m in the evening, or even 1200 m the following night.
Maximum temperatures: +12 to + 15 ° C at low altitude, +1 to + 4 ° C around 2000 m
Snowfall forecast at 2000 m until late night from Saturday to Sunday:

  • Bauges, Lauzière, Beaufortain and Haute-Tarentaise: 7-15 cm locally 20/25 cm towards Mont-Blanc.
  • Elsewhere: 5-10 cm (or even less than 5 cm in places in Haute-Maurienne)

Isotherm 0 ° C: 2000/2400 m then 1700/1900 m in the evening.
Wind at 2000 m: South then South West 60/80 km / h towards the Prealps, Lauzière, Beaufortain, a notch below elsewhere but with occasional gusts.
Wind at 3000 m: South to South West 60/80 km / h, slightly less towards Haute-Tarentaise and Haute-Maurienne.

Clouds and thunderstorms, return of precipitation in the evening
Clouds still numerous at dawn, especially in the mountains, dissipating somewhat in the morning. Fine temporary thunderstorms possible in most areas, but an increasingly dense cloudy elevation gain from the west in the afternoon. In the evening and the following night, return of precipitation, in the form of snow above 1200/1400 m (with 5-10 cm around 2000 m, more locally 15 cm)

Minimum temperatures: +1 to + 3 ° C in plains and valleys. Maximum: +10 to + 14 ° C at low altitude, 0 to + 2 ° C around 2000 m.

Isotherm 0 ° C: 1400/1800 m.
Wind at 2000 m: Southwest 10/30 km / h, increasing 50/70 km / h at the end of the day towards the Pre-Alps, weaker in interior massifs.
Wind at 3000 m: Southwest then West 20/40 km / h, increasing 50/70 km / h at the end of the day and evening.


MONDAY 2: Disturbed
Rainy weather in the plains, snowy in the mountains. Rain / snow limit 1400/1800 m, down to around 1000 m in the evening then a little lower the following night. Snow accumulations 15-30 cm around 2000 m, to be confirmed in the next bulletins.

Minimum temperatures: +1 to + 4 ° C in plains and valleys. Maximum: +9 to + 12 ° C at low altitude.

Isotherm 0 ° C: 2000/2300 m down towards 1200/1400 m in the evening.
Wind at 2000 m: South 50/70 km / h towards the Alpine foothills, weakening and tilting West 40/50 km / h at the end of the day. Lower in interior mass.
Wind at 3000 m: South-South-West 50/70 km / h, tilting West then North-West in the evening.
The weak current turns to the NW, accelerates, and becomes rapid from WNW overnight.
A little more sun; the precipitation becomes more scattered in the morning.
Isothermal 0 ° C around 800-900 m during the day, 1300 m at the end of the night, and the snow lower.

The current of WNW remains fast.
Many clouds, and general precipitation that seems marked.
Isothermal 0 ° C still rising around 1600 m during the day, then falling around 1000 m, and snow lower.

The current of WNW slows down a bit.
Many clouds, precipitation becomes less marked.
Isotherm 0 ° C around 900-1000 m, and the snow lower.

The current of WNW slows down a little more and turns to WSW.
A little more sun and passing precipitation.
The 0 ° C isotherm hardly exceeds 1500 m, and the snow stays lower.

Tip of the week

This week’s tip comes from avalanche expert, Alain Duclos, from data-avalanche.org in his advice to professionals during and after the upcoming snowstorms in the N French Alps in the next week or so:

“The best clue about avalanche danger is avalanches!!”

Or ‘recent avalanche activity’ as we call it at HAT. See our risk reduction framework on this link.