Off-Piste Snow and Weather Report 17-24 Jan 2019

For Savoie and Northern French Alps

Cold temperatures and a little more snowfall

With some fresh top-ups of snow (anything between 5 to 40 cm) we’ve been finding some fantastic off-piste conditions over the last few days. There’s some lovely cold powder snow still to be found, particularly on high North facing slopes. And it looks as if we’re due some more smallish amounts of fresh snow in the days to come.

Some great off piste snow conditions around, and more snow forecast. Wayne Watson photo

In high exposed areas the surface has often been wind-hardened and crusted (sometimes blown off altogether). In other places it’s been densified by the wind, although quite skiable.

A persistently fragile snowpack developed with the very cold temperatures, particularly overnight. Henry warned about the likelihood of avalanche accidents last Tuesday, which was a bluebird day sunny day following Monday’s snowstorms. However, we did not get as much snow as was forecast in the Savoie and the Isère. There was more snow in Haute Savoie and that led to some avalanche accidents. This is because a thicker layer of new snow on the weak layer creates more instability and that, in turn leads to more danger.

Given the relatively small amounts of snow forecast in the next few days, this probably won’t create generalised instability everywhere. However, when combined with wind, even just 5 to 15 cm of snow can be blown into an extra 40 cm or so in some places. That is enough to catch you out. Especially when it lands on a persistently fragile snowpack, such as we have at the moment. That’s based on the fact that over decades many accidents have happened in similar conditions to the current ones. At times they’ve even occurred when the avalanche danger rating has been low.

Remember, maybe nothing happened today, but that doesn’t mean that things are safe and that the right decisions were made. When nothing happens, and we don’t get any negative feedback, we let our minds coax us into very dangerous places on the off-piste slopes. That’s when ’risky behaviour’ becomes a habit, without us even knowing it!

Avalanche bulletin 17th Jan

Danger rating is 3 above 2200m and 2 below that. The risks are greatest on Northerly facing slopes from NE to NW due to the weak layer being worse on those aspects.

The calm weather since Tuesday allowed the recent snow to settle but some instabilities persist certainly in places (Italian ridges, shaded slopes).

Spontaneous departures: some releases may still occur during any period of bad weather.

Some windslab certainly persists above 2200/2400 m (skier triggered releases were observed on Tuesday in North to East exhibitions). The faceted grains are not sufficiently buried (angular grains) can promote a break in case of overload by one or more skiers, especially in North (North-West to Northeast).

Also there are places where 50cm deep slab can release.

Off-piste weather forecast for 17 to 24 Jan

General Outlook

A weak area of unsettled weather is currently crossing Savoie and Haute Savoie this will be followed by much colder weather and an uncertain weather situation for the weekend. Next week we will have high-pressure north of the alps and low pressure over the Mediterranean This means we will see a mixture of cold sunshine and clouds with a possible weak Retour d’Est on Wednesday.

Outlook beyond 27th January

Looks like high pressure is still the main influence but there will be intervals of disturbed weather. Generally very cold.

Clouds predominate and some light snow showers cross our mountains with a little snow from 300/500 m (less than 10 cm to 1000 m). The wind changes to the northwest (50 to 60 km / h from 3000 m). Minimum temperatures approach -4 to -6 degrees to 1000 m, -11 to -14 degrees to 2000 m and -17 degrees to 3000 m.

Numerous clouds in the morning (from 1500 to 2500 m) this will clear. Hazy sunshine in the afternoon. The north wind calms quickly (50 then 20 km / h to 3000 m). The cooling continues with maximum 0 to 2 degrees to 1000 m and -5 to -8 degrees to 2000 m (isotherm 0 degree between the 0m and 1200 m).

Expect sun despite some high clouds and perhaps some Cumulus on the slopes. The wind is weak from west to northwest at altitude. Temperatures remain low, moving from -6 to 0/2 degrees to 1000 m and -10 / -14 to -4 / -6 degrees to 2000 m (isotherm 0 degree around 1200 m).

The sun appears among some clouds, which cling to the summits, and probably more numerous in the afternoon or in the evening Maybe some light snowflakes. Weak west wind and still very low temperatures (-6 and then 2/4 degrees to 1000 m and -8 / -12 then -4 degrees to 2000 m).

Monday, the clouds prevail, with a small risk of snow to the valley floor. Colder with temperatures below averages ranging from -2 / -4 to 2/3 degrees in plain and -7 / -8 to 0 degrees to 1000 m.
Tuesday, probable return of cold sunny weather with some banks of high clouds. Wind still weak.

Low pressure system coming from the south and east with wind, clouds, clearings and possible snow on the Italian border. Temperatures without much change.

The Mediterranean depression moves away, allowing beautiful clear weather. Temperatures still very low (-8 then 0 degrees to 1000 m). To confirm.

Tip of the week

The biggest risk come from deeper slabs sitting on the weak layer. So watch out for accumulations of snow and fresh snow on any part of the mountain, even in just small localised areas. When these sit on top of a persistently fragile snowpack, like we have at the moment, an avalanche can easily be triggered by a skier passing by.

With cold temperatures forecast for the next few days this new snow will turn into faceted grains and create another weak layer. So if we get significant new snowfall the snowpack will still be unstable.