Off-Piste Snow and Weather Report 10 – 17 January 2019

For Savoie and Northern French Alps

Fresh snow is on its way … but if we get a lot, expect instability above 2500 m

The snow is coming. It looks like less stable weather now. But high pressure still dominates until 21st January. So several small snowfalls in the next week and generally quite cold and windy. Then expect low pressure and more snow after 21st January.

For the last week or so, we’ve been doing a lot of walking to find any decent off-piste snow. However, we’ve had a little fresh snow on Wednesday, and it looks as if more snowfall is on the way in the next few days.

Avalanche danger ratings have been down to 1 out of 5 below 2500 m, and at 1 or 2 above this altitude. That’s pretty rare for this time of year. (See our descriptions of what all the avalanche danger ratings mean).

We currently have two different types of snowpack, with 2400/2500 m (the rain/snow limit) as the demarcation zone between the two:

Below 2500 m, the snowpack has become very solid and stable due to becoming very humidified by rain and melting, followed by refreezing.

Above 2500 m, snow profiles show a very unconsolidated snowpack consisting almost entirely of faceted grains (‘sugar snow’), a situation which has come about because of very cold temperatures, particularly, cold clear nights. It’s fine as long as no substantial new snow lands on top of it. But when it does, it will become a very different story….

Once any substantial (say 20 to 40 cm) fresh or wind-blown snow lands on top of this unconsolidated snow above 2500 m there will be serious instability at these high altitudes, particularly on steep North’ish facing slopes of 30° and more. Below 2500 m, any fresh snowfall will be landing on a much more solid base.

See Henry’s video update on the current situation and what to look out for when we do get any substantial fresh snow (possibly at the beginning of next week).

Of course, it remains to be seen how much fresh snow we actually receive, and when. But beware of this instability, particularly on steep high North-facing slopes where the best quality snow often is. Be especially wary on the first sunny day after fresh snowfall, when we’re all itching to get out and enjoy the powder!

Off-piste weather forecast for 10 to 17 January

Currently, the western Alps are under a high pressure drawing in cold air from the N and NE. We expect some light snow, wind and clouds on Saturday to Sunday night. Then a period of very variable weather with some more light snow, sun, clouds, wind, cold and milder temperatures changing day by day.

This is because French Alps is sitting on the edge of two weather systems right now. A cold low-pressure system drawing snow into Austria and High pressure over the Atlantic and the Azores. The weather in the French Alps is unpredictable since it depends on which one of these is dominant. This persists until around January 20th or 21st.

From 21st January, it looks like the jetstream will sink south and place the western Alps under a low-pressure weather influence. This will bring the chance of more significant snowfall interspersed with sunny days. prpbably windy, but hard to say right now

What we can say is the the weather is much more unsettled now and we will see a lot more variation than in the past two weeks

 NIGHT of THURSDAY 10th Jan

The clouds give way and the stars appear again. Clouds persist around 1500/2000 m. The minimum temperatures are very low, are close to -8 degrees to 1000 m and -13 to -17 degrees from 2000 to 3000 m.

 FRIDAY 11 January

The sea of clouds rapidly disappears and the sun comes out despite some cloud in the afternoon (3000/4000 m). There are North to Northeast winds possible on the ridges (50 to 60 km / h). The atmosphere remains “icy cold” around 1000 m (0 to -2 degrees) for -6 to -9 degrees around 2000 or 3000 m.

 SATURDAY 12 January

A lot of sun despite banks of high clouds. The wind is from North to Northwest (40 then 60 km / h from 3000 m). The cold is still bright in the morning but the temperatures rise a bit, moving from -6 to 2 degrees to 1000 m and -13 to -3 degrees to 2000 m ( 0 degree between 900 and 1500 m).

 SUNDAY 13 January

Cloudy on the summits, the snowfall weaken temporarily, before resuming more at the end of the day and into the night. The rain/snow limit rises to around 1000 m before descending. 
Strong northwest wind (gusts 80 to 100 km / h from 3000 m). Temperatures rise from -3 to 4 degrees to 1000 m and -6 / -9 to -1 / -3 degrees to 2000 m ( 0 degrees temporarily 1500/1800 m).

 MONDAY 14 and TUESDAY 15 January

Monday, cloudy with snowfall that weakens throughout the day. Northwest wind still strong in altitude (60 to 80 km / h). Temperatures lower at night (0 degrees on valley floor) 
Tuesday, return of the sun in the mountains after a few morning clouds Temperatures evolving from -4 to 4 degrees to 1000 m.

 WEDNESDAY 16 and THURSDAY 17 January

Wednesday, probably sunny Before a possible clouds and snow Wednesday night and Thursday. Temperatures always a little low for the season.

 FRIDAY 18 and SATURDAY 19 January

Possible Northwestern regime disturbed and snowy in the mountains. To confirm.

Tip of the week

The snowfall will sit on a persistent weak layer above 2500m in the snowpack, always be on your guard after fresh snowfall, even when there’s little sign of recent avalanche activity.

After substantial amounts of fresh snowfall, always treat steep slopes above 2500 m with a lot of caution.