Weekly report from HAT - still snowing - 11/04/08

Henry's Avalanche Talk

Snow report from Henry April 11 2008

The skiing off-piste has been great lately despite totally unpredictable weather and days that you would think aren't going to be good.. but then turn out to be great! Getting out early (despite wind, bad visibility etc.), going as high as possible and looking for slopes that are sheltered from the wind seems to be the trick [winds have been coming out of the Southwest to South most of the time up until the 11th - that will change on Saturday 12th as the winds turn to the North and Northwest for most of the time until Wednesday 16 April.

The little snowfalls of 5-10 cm that have been falling with each passing storm has helped to provide fresh tracks and lots of fun on a lot of days recently. Adding to the these little snowfalls is the wind, which has helped to make accumulations in sheltered areas build up to quite a bit more than what fell out of the sky - but not so much as to make it very unstable (so far anyway). It looks like this weather trend will continue for at least a week. So get out there and find the good snow!

Snowpack Quality & Stability

The light snowfalls and wind have been forming some surface slabs, mostly above 2500/2700 m. The wind, the sun, warming and precipitation will encourage some instability and avalanche activity on sufficiently steep slopes, a little at all altitudes. Below 2500/2700 a relatively small surface slab may turn into a larger wet snow avalanches; above, they could lead to bigger slab avalanche too as dry/cold snow slabs.

The risk of these types of slabs will increase with each snowfall and I will be especially careful if we get 20 cm or more in one storm (or in a short amount of time like 48 hours) with wind, which can lead to twice the amount of snow that came out of the sky on sheltered slopes - the slopes that will have the best skiing.

Each day the Météo France avalanche forecast says that one skier is enough to trigger one of these surface slabs and that could even lead to a second slab releasing deeper into the snowpack below the first one. This scenario is what happened to my friend and colleague TJ last year - the conditions were not much different than now.

TJ was lucky to get away with only severe knee injuries and is just getting back on skis now after several knee operations. So, even though things seem safe/stable in most places, there are areas of real instability out there. if you keep that in mind, you're doing well.

Tip of the week

I'm sticking to the higher and north'ish' slopes for the best snow until we get some hot sunny days with good cold nights that will transform the snow on other slopes to nice smooth spring snow. I keep saying that I'll do our annual spring snow write-up soon, but I'm going to have to put that off again until next week.. or until we actually start getting some good spring out there, but it looks like cold temperatures and more 'mini snow storms' through Wednesday 16 April. So I'm happy to stick with winter for now!

'Ride Hard Ride Safe'!

Henry

PS We're still doing lots of transceiver training at the moment in Val d'Isère: 35 euros for saisonaires for a full afternoon of coaching, timed searches, basic rescue procedures & a waterproof reference card (wow!). Call Jamie on 06 23 05 75 09

Henry's Avalanche Talk

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