Good morning. This is Kevin Wright with the Chugach National Forest Avalanche Information Center on Wednesday, March 21st at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
Alpine areas will have a steady MODERATE danger rating because of multiple buried weak layers on all aspects. Late in the day we can expect South faces to progress to CONSIDERABLE if the sun is baking for more than a couple hours. Below treeline will have a generally LOW danger with pockets of MODERATE on sunny South aspects and areas with surface hoar problems. It’s a complicated snowpack that may be difficult to manage.
Snowfall on Monday was focused on the Northern Kenai peninsula, which buried a significant new layer of surface hoar and the old sun crust on South faces. Yesterday afternoon we saw a handful of natural slab avalanches within the new storm snow. The character and distribution of those slabs suggests buried surface hoar. The complicated assortment of different snowpack problems deserves a fair bit of thought when deciding where to ride today. Even “stable” slopes may have a dry sluff potential with fast moving loose snow entraining quite a bit of volume.
Concern #1 – Buried Sun Crust
South faces may look enticing, but the surface crust and buried crusts make them perhaps the most dangerous place to ride. We’ve had several reports of skier triggered avalanches on these layers in the last week including one that resulted in serious injuries.
Concern #2 – Buried Surface Hoar
Multiple layers of buried surface hoar are widespread and have been implicated in quite a few human triggered avalanches. This problem just got worse, with anCNFAIC Staff layer of surface hoar over the weekend, and anCNFAIC Staff storm that buried it on Monday. These weak layers have been found on all aspects and up to high elevations.
Concern #3 – Loose sluff and wet slab
Happy equinox! The sun has some serious punch to it, now that Spring has officially hit. South faces are getting hammered by solar power late in the afternoon. The heat is causing late day wet avalanches and sometimes inducing larger step-downs into the sun-crust layers. Nobody should be traveling on or close underneath South facing slopes late in the day.
The last snowfall was on Monday when 6-10 inches fell at Turnagain Pass and the Northern Kenai Peninsula. Girdwood did not receive as much snow from this storm. Yesterday’s sunny weather built yet anCNFAIC Staff sun crust on the surface of South faces.
Stable weather is expected today. Partly sunny skies, light wind, and temperatures into the lower 30s are forecasted.
CNFAIC Weather Page and the NWS forecast
Graham will issue the next advisory Thursday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.