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The tides have turned and the persistent slab is active again after receiving approximately 10″ of new snow and 1″ SWE on Thursday. Small to large Persistent slabs will be likely to human trigger today and naturals will be possible on all aspects, although more likely on East to South to West aspects, at all elevations. Dry loose sluffs will be possible to human trigger on steep slopes greater than 40º.
Remotely triggering an avalanche will be likely today which means you, your partner, and other parties are at risk of getting caught. Careful snowpack evaluation, cautious route finding and conservative decision making will be essential this weekend if venturing into avalanche terrain.
Thank you to the Palmer City Council for your generous financial support to HPAC.
Buy a map and support your local avalanche center. Maps will be available at Alaska Mountaineering and Hiking (AMH), The Hoarding Marmot, Backcountry Bike & Ski and on https://www.kickstepapproaches.com/hatcher-pass-map
These maps sold out in 24 hours but will be available again soon. Stay tuned!
Travel Advice | Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. | Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. | Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. | Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. | Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain. |
Likelihood of Avalanches | Natural and human-triggered avalanches unlikely. | Natural avalanches unlikely; human-triggered avalanches possible. | Natural avalanches possible; human-triggered avalanches likely. | Natural avalanches likely; human-triggered avalanches very likely. | Natural and human-triggered avalanches certain. |
Avalanche Size and Distribution | Small avalanches in isolated areas or extreme terrain. | Small avalanches in specific areas; or large avalanches in isolated areas. | Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. | Large avalanches in many areas; or very large avalanches in specific areas. | Very large avalanches in many areas. |
Numerous natural, human and remotely triggered avalanches were observed on Friday, March 26 after receiving 10″ of new snow and approximately 1″ of water.
Most notably is the remotely triggered avalanche on Marmot that crossed and closed the road.
Other remotely triggered avalanches on Marmot SW face.
Naturals on Marmot 3/26
Natural on Divide Ridge
Snomachine triggered
Human triggered
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
Small to Large Persistent Slabs, 8″ to 2.5 feet deep, will be likely to human or remotely trigger today on all aspects, although more likely on East to South to West aspects where stout crusts exist, at all elevations. Naturals will be possible. Expect small avalanches in many areas or large avalanches in specific areas.
Thursdays 10″ of new snow and 1″ of water was clearly enough to tip the balance in the snowpack. Storm slabs, shallow wind slabs, and persistent slabs were all observed on Friday. Most notably were the remotely triggered storm slabs failing on persistent grains which stepped down into the old weak sugary faceted snow.
A widespread weak layer of buried near surface facets (and facets/depth hoar in the bottom of the pack) and a widespread crust bed surface exist in much of the terrain at Hatcher Pass. Finding a slab will be the one variable that determines whether you trigger an avalanche or not. There are two persistent slab problems. Shallower problem: Today it will be possible to human trigger or remotely trigger avalanches failing 8-12″ deep on the buried near surface facets sitting on the suncrust/drizzle crust or drizzle crust, depending on aspect. Deeper problem: The second concern is the deeper weak faceted sugary layer buried 2 to 2.5 feet deep. It will be possible to trigger either or both of these weak layers.
Triggering avalanches remotely can be an especially dangerous situation. Someone does not need to be on slope to trigger the avalanche. Especially in a snowpack with high propagation potential, a person can initiate a fracture from some distance away. We call these “remote” triggers. It’s common to remotely trigger an avalanche from the ridge above a slope, a gentler slope next to the avalanche and especially from a flat or gentle area below the avalanche. Needless to say, if you remotely-trigger an avalanche, the snowpack is extremely unstable and you need to choose your routes very carefully.
Conservative decision making will be the name of the game this weekend. Tracks on a slope are not an indicator of stability. Red flags such as cracking, collapsing, whumping are signs of instability.
Safe Travel Habits Save Lives
Signal Word | Size (D scale) | Simple Descriptor |
Small | 1 | Unlikely to bury a person |
Large | 2 | Can bury a person |
Very Large | 3 | Can destroy a house |
Historic | 4 & 5 | Can destroy part or all of a village |
Small to large dry loose sluffs will be possible to human trigger today on slopes steeper than 40º.
Thursday’s 10″ of new snow combined with near surface facets and cooler temps overnight will sluff easily today, although slower moving, and fail on the sun/drizzle crust which will make for a good bed surface.
We recommend using good sluff management if you decide to step out into steeper terrain. No matter the size, these avalanches can catch, carry and sweep you through hazards, if not managed properly.