Turnagain Pass

Portage/Placer: Skiers triggered two small but wide-propagating avalanches, suspected to be on a weak layer of surface hoar and stellars buried 1-1.5′ deep. They also saw a natural avalanche that they thought had stepped down to the same weak layer on Byron (photo below).

 Natural avalanche on Byron that looks to be a wind slab that stepped down to another layer, suspected to be a combination of surface hoar and stellar dendrites. Photo: Mike Welch, 02.12.2022.

Wind slabs are once again the primary concern today, as moderate southwest to southeasterly winds overnight and early this morning will build a fresh round of small but reactive wind slabs with the low-density snow that was on the surface yesterday. The key terrain features to watch out for will be steep slopes near ridgelines, convex rollovers, and steep gullies. Because the soft snow on the surface is so light, it won’t take much wind to move it around. This was the case yesterday in the Summit Lake area, where we noticed snow blowing off some ridgelines with weather stations only registering winds at 5-10 mph. Luckily this problem is relatively easy to identify and thus avoid. Be on the lookout for stiffer snow on the surface, and pay attention to warning signs like shooting cracks, collapsing, and fresh avalanche activity. This will require taking a few seconds to hop off your machine or step off the skin track and poke around in the snow to see how it feels. If you are trying to get on steeper terrain, be sure to follow safe travel protocols. This includes only putting one person at a time on steep slopes and watching your partners from safe spots out of the way of avalanche hazard.

We might see a slight increase in winds late this afternoon, especially at the higher elevations. Pay attention to changing conditions, with the potential for more sensitive wind slabs developing if the winds do pick up even a little bit. Keep an eye out for blowing snow along ridgelines as well as the red flags mentioned above.

Cornices: Strong winds over the past week have created very large cornices. Skiers reported natural avalanche activity triggered by a cornice fall up Virgin Creek earlier in the week (details here), and we have seen debris from cornice falls throughout the area. Be sure to give cornices plenty of space if you are travelling along ridgelines, and limit the time you spend below them.

Loose Dry Avalanches: Sluffs will run fast on steep terrain with soft snow sitting on top of firm surfaces left from last week’s strong winds. These are unlikely to bury a person, but can be dangerous if they were to carry you over consequential terrain like rocks, cliffs, or trees.

Debris from natural dry loose avalanches on the north side of Cornbiscuit. Human-triggered sluffs will be likely today in steep terrain that has not been hit by winds. Photo: Andy Moderow. 02.12.2022

Debris from an avalanche triggered by a natural cornice fall up Virgin Creek earlier in the week. Photo: Peter Ostroski. 02.11.2022

For some time now we have been mentioning the potential for deeper avalanches failing on layers of facets surrounding crusts from New Year’s and all the way back to the Halloween storm. These layers are concerning in areas with a thinner snowpack, which are most likely found on the fringes of our advisory area (Lynx Creek, Silvertip Creek, Crow Pass area) and outside of the advisory are in Summit Lake. We saw natural and human-triggered avalanches failing on these layers during the strong wind event in the middle of last week (details here),  and have found concerning snow pit results over the past few days in the Crow Creek and Summit Lake areas. The same layers have not given any cause for concern recently in the rest of the Turnagain, Placer, and Girdwood areas. Keep this distribution in mind, especially if you are planning on getting out in the zones that have thinner and more problematic snowpack. Without a big loading event, these layers will be stubborn to trigger, but the potential is still there. This requires adjusting terrain accordingly, and avoiding steep and consequential slopes for the time.

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