Sunny, settled Spring-like conditions for the week ahead in the N French Alps!

Macron has closed the schools in France but ski resorts in France remain open.

We’ve had some excellent off-piste skiing over the last week with some great powder snow conditions, particularly while temperatures stayed cold. We’re lucky to still be able to ski from around 1400 m and above. At the time of writing (12th March) the Val d’Isère/Tignes ski area boasts 100% of its ski lifts open.

Off-Piste Snow Depths for the Haute Tarentaise 11 March 2020 by Meteo France

It has now become warmer, with much more spring-like snow conditions. The best off-piste conditions are on high cold north-facing slopes, where there is still some colder snow to be around. We’ve already seen some ‘spring snow’ conditions appearing, which will probably become more established next week.

The snow is often crusted first thing in the morning, following overnight refreezing. It quickly softens as the day goes on, becoming sticky, slushy and heavy later on in the day.

This weekend and next week look like being sunny, settled and mild. Nights should be starry and cold. Ideal conditions for ‘spring snow’. By ‘spring snow’ we mean the lovely smooth, soft snow that occurs in spring after a few melt-freeze cycles (not the thick afternoon slush or rock hard morning snow that we also find in spring)! Off-piste spring snow is one of the best things that the Northern French Alps has to offer.

Following a few proper ‘melt-freeze’ cycles the top snow layer starts forming a crust that deepens and strengthens after each melt, allowing free water to drip down and re-freeze during the night. (One melt-freeze cycle is where the snow melts during the day and then freezes at night). If untouched, the top of the frozen layer is smooth and solid first thing in the morning. It softens as the day goes on, melting in the warm sun and increased temperatures.

The softening process starts on east facing slopes which receive the sun first. It moves onto the south, then the west facing ones, following the sun’s movement. (North facing slopes at 2500+ metres don’t normally get a melt freeze layer until late April, due to lack of sun).

Recent history of the snowpack

We’ve had 3 recent episodes of fresh snowfall (10 cm or so a time), along with warmer temperatures. Rain on Thursday night has saturated the snowpack before it refreezes. This could act as a primer to get the snowpack ready for spring snow conditions.

With a lot of snow around and warm temperatures, we have seen (and will probably continue to see) avalanches happening later in the day, as things warm up. See the photo from Christian Appertet below – we saw plenty of these sort of naturally occurring slides in the warm temperatures this week. These avalanches could be quite large in size.

Direct action avalanche. Photo by Christian APPERTET

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

As we write, the avalanche risk is 3/5 on all aspects and altitudes. Melting of the snowpack due to mild temperatures, helped by Thursday/Friday’s rainfall, followed by overnight refreezing will help with stabilising the snowpack. There are many possibilities of wet snow slides mentioned in the bulletin, due to high temperatures. Plus new dry snow slabs above 2500m

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

Where is most at risk at the moment?

  1. Steep slopes with terrain traps beneath them are always going to be particularly at risk.
  2. Also look out for direct action avalanches occurring on snowy slopes affected by rapid warming, during and just after snowstorms.

How does the forecast look for the coming week?

Generally mild temperatures with a lot of sun and some clouds with occasional precipitation. Much more stable weather with high pressure in charge for the foreseeable future.

FRIDAY 13th March

Improvement, milder temperatures
The last drops / flakes of the night’s disturbance disappear quickly at the start of the morning and most of the clouds disintegrate, except locally near the Bauges, Lauzière and even Beaufortain, where they can persist a little longer during the day. But generally, the weather is generally very sunny with high cloud passages, and some cumulus clouds in the afternoon in the mountains.
Maximum falling temperatures: +13 to + 15 ° C at low altitude, +3 to + 5 ° C around 2000 m.

Isotherm 0 ° C: 1500/2000 m (Pre-Alps), 2000/2700 m (interior massifs), 2800/3000 m (Haute-Maurienne).
Wind at 2000 m: weak variable.
Wind at 3000 m: North-West 40/60 km / h (locally 70 km / h in Haute-Maurienne), weakening a bit in the afternoon.

Clouds and sunny breaks
Cloudy passages circulate over the department, alternating with cloudy periods. These clouds can catch the massifs and give fog in high mountains. In plain and low valleys, the thinnings are more beautiful and more durable.
Minimum temperatures: +2 to + 4 ° C in plains and valleys. Maximum: +12 to + 14 ° C at low altitude.

Isotherm 0 ° C: around 1400/1700 m (locally up to 1800/2000 m in Haute-Maurienne).
Wind at 2000 m: North 10/20 km / h towards the Pre-Alps, variable weak elsewhere.
Wind at 3000 m: West then North West 20/40 km / h.

Mild, dry and sunny weather, with some cumulus in the afternoon towards the Avant-Pays and the Bauges. The border ridges of Haute-Maurienne can be hung by clouds from Italian Piedmont. Slight Foehn and Lombard trend in their field.
Minimum temperatures: -1 to + 4 ° C in plains and valleys. Maximum: +16 to + 18 ° C at low altitude.

Isotherm 0 ° C: around 2500/2700 m (locally 2000/2300 m near the Italian border).
Wind at 2000 m: South to South-West 20/30 km / h towards the Pre-Alps, light South-East in interior massifs.
Wind at 3000 m: South to South West 10/30 km / h.

Clouds are more numerous over the department, and light rain is possible over western Savoy. Elsewhere, precipitation is more anecdotal, even non-existent towards the Haute-Maurienne.
Isothermal 0 ° C around 1800/2100 m.
Generally sunny and mild, with a few passing altitude clouds and cumulus clouds which can appear in the afternoon on the terrain.
Isothermal 0 ° C around 2500/2700 m.

Sun and mild, a few clouds in the afternoon in the mountains. Isothermal 0 ° C around 2500/2700 m.

The weather remains dry. A mix of cloudy periods and sunny periods, temperatures above normal. Isotherm 0 ° C around 2300/2700 m.

Continued dry weather, clouds and thunderstorms share the sky. Temperatures down slightly. Isotherm 0 ° C around 1800/2000 m at the end of the period.

Tip of the week

Follow the ‘melt-freeze’ cycles and get the most out of skiing the spring snow :

Start your skiing on east facing slopes which receive the sun first. Move onto the south, then the west facing ones, following the sun’s movement. That way you’ll get the best of the spring-snow conditions that we’re hoping will come into place next week.