Weather > Snow Avalanche Conditions > December 2005
Updated 30 December 2005, 20:00
We were ski touring in the Northern Belledonne range yesterday. There is an impressive amount of dry, light powder from the midweek snowfalls especially in hollows and bowls. In places this is sitting on a base of breakable crust which requires a bit of respect. Cols and ridges are pretty bare in places or have windblown snow which is less agreable.
What is interesting is how much of this snow has been falling between 500 and 2000 meters. As you climb higher you come out of the cloud and the snow gets noticable thinner on the ground, especially above 2500 meters. Thursday and Friday were very cold with a new weather front blowing in on Friday afternoon bringing with it slightly warmer temperatures which were assisted by the wind swinging around from the North-West to South-West. We didn't notice any particular avalanche activity except for an old slab but still took care about group spacing on some of the steeper pitches. Avalanche danger is high this weekend in the Northern Alps, especially above 2000 meters where the underlying snow has little cohesion. The situation is similar in the Pyrénées with the strong North-West winds forming fresh snow slabs on many slopes, the danger is considerable above 2200 meters with further snow expected on Sunday.
Updated 28 December 2005, 22:00 While certain parts of France have been snowbound just 10 to 20cm of new snow fell this morning in the Northern Alps. However this was largely confined to mid-mountain areas. As we climbed above the clouds into hazy sunshine at 2000m the snow pretty much stopped to be replaced by a biting northerly wind. The fresh snow has fallen onto some crusty old snow which is still making itself felt in places. Further snow is expected in the Massif Central, Vosges and Jura with snow returing to the Alps over the weekend above 1500 meters. There has been little significant snowfall in the Pyrenees where snow depths are average and breakable crust can be found on most slopes.
Updated 24 December 2005, 08:00 No new snow is expected until around the middle of next week. The wind has had an effect and there are a lot of stones and rocks visible on any exposed slope. This also means that soft snow can still be found in hollows and bowls but you have to watch out for patches of the dreaded crust. Best conditions seem to currently be on west facing slopes in the Northern Alps. There is a lack of snow in the Southern Alps. The Pyrenees have good snow conditions for Christmas. We noticed surface hoar had formed between 1400-1700 meters on sheltered slopes and higher up the base consists of a good layer of snow with little cohesion.
Updated 22 December 2005, 09:00 A high is currently sitting directly over France which will bring fine weather through until after Christmas with little prospect of fresh snow. Most of the alpine valleys are currently under an inversion layer (creating a cloud-sea effect). Temperatures are below average and set to get colder over the weekend. Things to watch out for are surface hoar development around the inversion layer level and strong temperature gradients creating facetted crystals (loud powder), both potential weak layers especially after the next snowfall.
Updated 21 December 2005, 17:00
We were ski touring in the Belledonne today. There has not been much change in conditions other than there was a strong inversion layer in some valleys (as far as the Tarentaise from our vantage point). The weather continues to be cold. Powder can still be found along with hardpack with a little bit of breakable crust to catch you out. Conditions appear more stable, the danger of avalanche remains localized due to a thin layer of facetted (weak) snow at ground level, this is principally on north sector slopes above 2400m especially close to cols and ridges. Group spacing is very important in these areas.
Updated 17 December 2005, 19:00 We have been ski touring in the Chartreuse today, a new variant of an old route. The "30cm" of fresh snow announced in Meteo France's "snow alert" failed to materialize. Instead we had between 2-5cm of snow on a very humid and crusty base. Reports from the Belledonne and Oisans were no better but the Aravis did seem to get its fair share of the fresh - 40cm in the bowls at 1500m with 10cm making it over to Mont Blanc and 20cm in the Tarentaise. Still we managed to find some reasonable accumulations formed by the strong North-West wind. These will also present an avalanche risk where accumulations are significant, especially given the condition of the existing snow. Avalanche control work with explosives in the Savoie has given results in the sector north through to south.
Updated 16 December 2005, 23:00
Around 20-30cm of new snow is expected in the Alps tonight accompanied with strong winds from the West to North-West. This will rest on a surface hardened by the sun and wind. New slabs will form under the action of this wind, principally on south sectors but there may be large accumulations elsewhere (crossloading etc). The danger is greatest in the pre-Alps where most of the snowfall is expected and at altitudes above 2400m. Care is advised for the weekend.
Some light snow is expected in the Pyrenees accompanied by strong North-West winds. The conditions remain above average. There is still a danger at higher altitudes, especially on north facing slopes close to ridge lines. There have already been a series of fatal avalanches in the area.
Third Avalanche in a Week for Piau
Updated 13 December 2005, 19:00
The recent warm weather, 2C at 1800 meters, has made off-piste conditions somewhat tricky with a sun crust on south facing slopes and just to round off the north-east wind has left a wind crust on north facing slopes! In the valleys temperatures have been much colder due to a temperature inversion so watch out for surface and possibly facetted snow at lower elevations.
Updated 12 December 2005, 15:00
Judging by the number of people in the mountains this weekend really kicked off the winter season with some very good skiing and boarding. The weekend also saw a very strong temperature inversion in the Alps. In the Vercors today it was -10C at 1000m and +2C at 1500 meters. The natural consequence is a sea of clouds. Some surface hoar has also formed around 1600-1800 meters - we noticed this on a shady north facing slope in the Belledonne.
The snow has begun to settle on south facing slopes with some snow slides in places. Glaciated terrain remains tricky with many crevasses hidden by weak snow bridges. Skiing is possible from around 900-1000 meters. Rocks are still near the surface off marked ski trails. Snow cover remains thin near the frontier with Italy. There are a number of slabs present close to cols and rigdes, these are on north to east sector slopes but the change in wind direction since Thursday (from the North and East) will have formed new slabs on south / south west sectors. The danger is most significant above 2400 meters and also where there are large accumulations in the pre-Alps.
Updated 06 December 2005, 19:00
There was a further 5-15cm of fresh snow over the Northern Alps last night which fell down to 1000m in the Chartreuse mountains. This gave us a nice layer of powder for our tour up to the 2082m Chamchaude mountain - a classic route for the Grenoblois. We made the trip in bright sunshine between two weather fronts - a piece of good fortune (or planning) referred to as a "hold-up" by the French. Last weekends gale force winds from the south obviously did some damage as, despite the excellent powder, there were still some nasty rocks poking up in places. Still the conditions in mid-mountain areas are steadily improving. The stability of slopes below 2000m is slowly improving with warm daytime temperatures. Caution is still advised higher up especially on shaded slopes (depth hoar/facetted snow) where there are large accumulations of snow.
Updated 05 December 2005, 10:00 Yesterday we made a tour to the Grand Rocher, a favourite route when conditions are indifferent. At 1900 meters there was 45cm of snow on a north-west facing slope and 80cm the other side of the ridge facing north-east. An indication of how much snow has been moved around by the recent wind.
Weve heard reports of a number of small avalanches nothing serious so far - and of a lot of slabby slow on north-sector slopes. The weekend also saw a considerable warming of temperatures. Yesterday at 13:00 we encountered a mix of snow and rain with an air temperature of +1C.
Conditions in the pre-Alps are reasonable. Skiable, albeit humid snow, starts around 1200 meters and there is some 60-80cm of snow at 2200m. However many routes are impractical due to the strong winds removing snow from windward slopes. The conditions in the Haute-Maurienne, Mont-Blanc and Haute-Tarentaise remain poor. It is currently snowing above 1500m.
Conditions are good in Corsica with ski touring possible from 1100m. In Pyrenees ski touring is practical from 1800m except on grassy slopes due to the lack of base. There have been a number of avalanche incidents over the weekend including one fatality.
Updated 03 December 2005, 10:00 The snow/rain line was around 1600 meters overnight with around 40 cm of fresh snow in the Pre-Alps at 2500 meters. There was very little snow in the Haute-Tarentaise and Haute-Maurienne but a very strong Foehn wind that caused delays on the Chamonix Mont-Blanc tunnel.
Updated 02 December 2005, 09:00 A low pressure currently situated in the Bay of Biscay is bringing a new weather front across France and strong winds from the south to south-west. Over the last 12 hours the wind speed has increased markedly 35km/h average at 2000 m and gusting to 80 km/h. This has clearly blown the light snow that fell last Friday and Tuesday onto north sector slopes forming slabs. Above 2400/2700 these are resting on snow that has been destructured by the recent very cold weather for example at la Grave the 20cm of snow that fell during the autumn was subject to -20C temperatures on the surface, creating a temperature gradient of around 100C / meter. This very strong gradient forms weak depth hoar crystals in the snowpack.
Currently the pre-Alps are favoured with the best conditions. The snow cover is poor in the Oisans, Vanoise, Haute-Tarentaise and Haute-Maurienne and Mont-Blanc.
The warm Foehn or Chinook wind and weather front will bring rain below 1500-1800 meters over the course of Friday. This will humidify the snow below that level and could lead to some wet snow avalanches. The wind will move around to the West. Saturday will see some sunshine with the risk of snow sluffs. Snow will return to lower altitudes (1000m) on Sunday evening/Monday. Around 60-80cm is anticipated over the weekend at 2500m. Backcountry travellers should take great care on steeper slopes, couloirs and cold shaded aspects.
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