HAT Snow Report Jan 30, 2010
If you walk, you will find good untracked snow! That has been the theme for earlier this past week through this past Wednesday.
Snow Quality and Stability
Over the past week, the snowpack has been stabilizing in much of the Northern French Alps. Météo France moved the danger rating from 3 to 2 on the international avalanche rating scale earlier in the week (see www.henrysavalanchetalk.com under ‘Free Information’ for definitions of these ratings). However, I’ve noticed that the top 10 to 40 cm of the snowpack, was starting to become a cocktail of cohesionless grains of snow by early/mid-week (made up of faceted/angular grains and some surface hoar created thanks to the cold temps) which gave that nice soft top layer a sort of granular feel to it rather than the light smooth feel of fresh new snow.
I mention this because even though this top layer was nice to ski in earlier this past week (on most slopes except South due to a a nasty melt crust) it does become a weak unstable layer once it is buried under the new snow or snow transported by wind. I’m paying particular attention to this newer cohesionless layer above 2200 metres and so should you.
There is also a persistent weak layer of cohesionless snow deeper down (approx 60-75cm or more down) in the snowpack that dates from the cold snap of early/mid December. This layer is still an issue above 2500 metres or so because these slopes/altitude didn’t get the rain in late December that ultimately had a stabilizing effect on the snowpack from 2500 metres and lower. Large increases in weight, like groups of skiers together on a steep slope can trigger a very large/deep slab avalanche due to this deep weak layer.
Météo France is warning people to still be careful on steep East to North to West slopes above 2200-2400 that could be susceptible to the weight of a group of skiers - and if there’s more snow (as is predicted!), these slopes could become more and more sensitive e.g. the weight of even a single skier could trigger a slab avalanche.
Tips for this coming week
Remember that most of the time an unstable slope will not avalanche.., but they do on occasion; sometimes taking peoples lives as we have seen this season already. SO, look above and below you – don’t stop in groups in exposed areas! Even when things get ‘stabler’ and the danger rating comes down, you can still set slopes off especially if you are grouped up in the middle of steep slopes.
Stick to going one at a time on steep slopes (or below steep slopes) and stop in places that aren’t exposed to slopes above and aren’t exposing you to cliffs, holes, lakes and other nasty stuff below you.
Have Fun and Be Safe!
Off Piste & Avalanche Awareness Talks: Week of 1 February:
Monday (on bad weather days) 15.30 sharp Basic Talk at the Moris in Val d’Isère Weds 18.00 sharp Basic Talk at the Pacific Bar in Val d’Isère You need to show up at least15 mins before the talk to take advantage of the deals on food & drink!
Tickets are €7.50 (one person under 18 per adult free) and includes great deals on food and drinks at each place! Pre-booking on line price is: £6 on www.henrysavalanchetalk.com (if you can’t come to a talk see our on-line talks on the web site)
HAT is taking the Talks on-snow this year for people who want to learn more in Val d’Isère & Tignes!
See www.henrysavalanchetalk.com for more info on these practical short courses.
