Douglas Island Avalanche Forecast

We triggered a wind slab on a steep west-facing roll at about 1600′ elevation in the Tincan Trees yesterday afternoon. It was on a smaller terrain feature, but the slab was 6-18″ thick, 75′ wide, and ran about 50′. There were some small surface hoar grains on the bed surface.

It is looking like the clouds are going to break and winds will die down after four days of stormy weather, but the avalanche danger remains elevated. Heavy snowfall and strong winds have buried a layer of surface hoar 1-2′ deep or deeper, and that setup is likely to remain reactive today. Winds have shifted from easterly to westerly over the past 24 hours, so we can expect to find sensitive wind slabs on all sides of the compass. This has created a challenging setup in the upper snowpack, with potentially two rounds of reactive wind slabs that may be capped by soft snow, making them a little harder to identify. The areas that received more snowfall over the past four days (Portage, Placer, Girdwood) will be more dangerous today. This is especially true for the Squirrel Flats and Skookum areas. The same can be said for upper-elevation start zones near ridgelines, convex rolls, and gullies, which have all seen some kind of wind loading during the storm.

Just to make things a little more interesting, we are expecting to see full sun by mid morning, along with mild temperatures. These new snow instabilities are likely to become more touchy as the snow surface heats up, and there is a chance we could see some natural wet loose avalanches triggering storm and wind slabs by this afternoon.

Long story short, despite the clear weather this is not a ‘game-on’ type of day. We have limited info of avalanche activity during the storm, and what little info we do have is indicating that the layer of buried surface hoar will be a concern. Keep a conservative mindset today, seeking out information from the snowpack before easing out on to steeper slopes. Be on the lookout for red flags like shooting cracks, collapsing, and fresh avalanches. Take the time to hop off your machine or step off the skin track and see how well (or how poorly) the new snow is bonding to the old snow. If you see any concerning signs, stick to low-angle slopes and give the storm snow some more time to settle out.

Deep Persistent Slabs: For the zones with a thinner snowpack around the periphery of our forecast area, this storm has loaded a snowpack with deeper weak layers. This is the case in the Crow Creek, Johnson Pass, Lynx Creek, Silvertip, and Summit Lake areas. It is unlikely, but not impossible, that a person will trigger an avalanche on these deeper layers today. It is still worth keeping this potential for a very large avalanche in mind if you are planning on getting out in any of these zones.

In the far northern and southern portions of our forecast area (i.e. Crow Creek, Lynx Creek, Silvertip Creek) the snowpack is thinner and the potential for triggering a large avalanche on a layer of facets from November exists. Yesterday we found the November facets only 6″ down from the surface in a wind scoured area near Crow Creek. This was quite surprising and indicates that human triggered avalanches could be possible on this deeper weak layer if a failure is initiated in a thin spot of the snowpack. Recent avalanche activity on this layer has been associated with significant snowfall events and since these thinner snowpack areas of the forecast region have not received much snow the past three days the likelihood of an avalanche on this layer is relatively low

Stormy conditions are returning to the area, with increasing winds this morning ahead of a round of precipitation that could bring over a foot of new snow to Turnagain Pass and Girdwood and 2-3′ to Portage and Placer by tomorrow morning. The avalanche danger is expected to rise as the storm progresses, and today the main factor determining stability will be the timing of the storm. Winds are currently blowing 10-20 mph out of the east with gusts to 45 mph, but are expected to pick up to 20-40 mph during the day. While the most intense precipitation will likely be overnight, we can still expect to see 3-5″ snow by the end of the day today with slightly more in Portage and Placer. Combined with the strong winds, this will be enough to make human-triggered avalanches up to a foot deep likely, especially in the upper elevations.