Turnagain Pass Avalanche Forecast

We did not hear of any avalanche activity yesterday during the stormy weather. On Monday folks were able to trigger large sluffs on steep slopes. The last slab avalanche was on Saturday when a skier triggered a slab around 2′ deep on a lower elevation rollover on Eddie’s Ridge.

The Valentine’s Day Storm headed out quicker than anticipated last night and left us with 4-10″ of new snow. The Girdwood, Portage, and Placer valleys were favored with closer to 10″ while Turnagain Pass picked up 4-6″. Ridgetop winds during the the snowfall were easterly in the 20’s mph with gusts near 60mph. The winds died off as well last night and today we are expecting low clouds, possibly some sun peaking through, and very light westerly winds.

The main avalanche concern will be the wind slabs that formed yesterday. These should be found near ridgelines, in cross-loaded gullies, and on rollovers in exposed areas. Wind slabs will hopefully be easy to suss out by watching for wind loaded areas, stiffer snow over softer snow, and hollow feeling snow. Cracks that shoot out from you are also a sign you’ve found a wind slab. Over the last week there has been light snow trickling in with some surface hoar forming here and there. This means wind slabs could be more ripe to trigger as they may take a bit longer to bond.

Storm Slabs:  In areas sheltered from the wind, look for how much new snow has fallen. In areas seeing up to 10″ of new snow we could trigger shallow storm slabs at all elevations that are composed of the new snow. In areas with less snow, storm slabs should not be an issue.

Cornices:  As skies clear and travel along ridgelines becomes easier, be sure give cornices a wide berth.

Loose snow avalanches:  Watch your sluff. There is a lot of soft surface snow out there and sluffs triggered on steep slopes could run much further and generate more volume than anticipated.

Under the new storm snow are various layers that could be potential problems that would create larger avalanches. These are a couple layers of surface hoar that formed on really light snow last week. They have not been a concern yet, but something we are watching. These layers would be in the top foot or so of the snowpack.

Next is an old storm interface from Feb 5/6 that sits around 2-2.5′ deep. This interface was responsible for our last slab avalanche (a skier-triggered avalanche on Eddie’s last Saturday). That storm buried a layer of low-density snow sitting on a crust up to about 2000′, and there may be some spotty surface hoar at that interface in some areas. There is still some uncertainty with this layer.

In addition to that 2/5 interface, we are still keeping the 1/10 buried surface hoar layer on the radar. This layer is becoming less and less likely to make avalanches, even though it’s quite east to see in snowpits.

For areas with a thinner snowpack (Silvertip, Summit Lake), the weak layers near the bottom of the snowpack are still a factor in our terrain choices. This includes the weak snow around the Thanksgiving crust, as well as faceted snow at the bottom of the snowpack. Luckily these layers do not seem to be a factor in our core advisory area, but they are still a concern around the periphery.