Sunday afternoon through Tuesday evening brought a warm and windy storm to the core advisory area scouring many ridges of snow, and building dense wind slabs on leeward slopes. With ridge top winds predominantly from the East, expect West-facing slopes, particularly in the alpine to have that dense, pillowy look, indicative of wind slab (see photo below). The steeper the terrain today, the more likely you will be to find and trigger a wind slab. Likely trigger points include areas where the slab thins or near rock outcroppings. It’s important to keep in mind when dealing with this avalanche problem that wind slabs are notorious for luring skiers well onto a slope before failing, often times above a skier.
At treeline elevations winds were quite erratic during this storm so expect wind slabs to have formed on a variety of aspects. It’ll be time well spent today to seek out small test slopes (with zero consequences) on your skin up toward alpine and jump on these hollow-sounding slopes to see how the snow reacts to a skier’s weight.
All signs are pointing toward a storm layer that will stabilize relatively quickly but as always, it’ll be prudent to pay attention to any red flags the snowpack is giving us and practice safe travel protocol both on the ascent and decent today.
Notice the difference in texture between a wind-scoured ridge (safer travel option) and a wind-loaded slope where the slab exists.
Though it’s been a full two weeks since we saw peak avalanche activity on a buried surface hoar layer in the Turnagain zone, it’s still proving reactive in snow pit tests. This last storm added significant weight to these weak layers where wind slabs formed (though not uniform across the landscape), but judging by the lack of natural avalanche activity yesterday it doesn’t appear to have definitively tipped the stress vs. strength balance. Currently dormant in terms of avalanches, the nature of a persistent weak layer is such that it can return to a state of activity as more stress (weight) is added and thus we’ll continue to track and test these buried weaknesses as we ski into a new year.
Yesterday was a relatively mild day across the forecast area as the most recent storm ended rather quickly Tuesday night/ Wednesday morning. Winds dropped off precipitously with a 24-hour average of only 5mph on Sunburst and temperatures hovering around the freezing mark at 1,000′ under mostly cloudy skies yesterday. Turnagain pass saw just a trace of snow with a few lingering rain showers in the Girdwood Valley during the afternoon hours.
Today will mark the beginning of a pattern change in south-central Alaska as we transition into northern flow. This boils down to clearing skies and temperatures slowly dropping throughout the day to the mid to high-20’s at 1,000′ before falling significantly overnight. With this change in flow direction we can also expect a NW wind to kick up in the 18-33mph range at ridge top levels. No snow accumulation is expected today or throughout the weekend as temperatures continue to drop. By Saturday, high temperatures are only expected to reach the single digits under mostly sunny skies.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||32||Trace||.1||35|
|Summit Lake (1400′)||30||0||0||7|
|Alyeska Mid (1700′)||33||0||.01||26|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||27||ESE||7||20|
|05/06/20||Turnagain||Avalanche: Pastoral Peak, north face||Andy Duenow|
|04/10/20||Turnagain||Avalanche: Wolverine||Mike Records|
|04/10/20||Turnagain||Observation: Eddies lookers right shoulder||Matt Yoder|
|04/09/20||Turnagain||Observation: Bench Peak||Mike Records|
|04/04/20||Turnagain||Observation: Pete’s North||Anonymous|
|03/26/20||Turnagain||Avalanche: Tincan – Proper (SW facing)||CNFAIC Staff|
|03/26/20||Turnagain||Avalanche: Seattle Ridge||W Wagner Forecaster|
|03/25/20||Turnagain||Avalanche: Sunburst Uptrack @ 2000′||J. Boisvert|
|03/24/20||Turnagain||Observation: Turnagain – Road Observations||W Wagner Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
This is 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.