Turnagain Pass Avalanche Forecast
The avalanche danger is CONSIDERABLE above 2500′. Snowfall and wind throughout the day will build fresh wind slabs up to 1′ deep. The new snow is falling onto an icy snow surface and wind slabs forming along upper elevation ridgelines will be likely for human triggering and possible for natural avalanches. There is some uncertainty about whether lingering deeper weak layers could become reactive again with this added snow load.
From 1000′ to 2500′ the avalanche danger is MODERATE. Wind slabs are less likely in this elevation band and there is potential for wet loose avalanches associated with daytime warming. Below 1000′ the avalanche danger is LOW. A springtime melt freeze cycle is in place at lower elevations and the snow surface will likely soften throughout the day and make wet loose avalanches likely in the late afternoon and evening.
Avalanche Center End of Season Operations: This is our last week of 7 day/week forecasting. Beginning April 17 we will forecast 4 days/week (Tuesday, Thursday, Saturday, Sunday). The final forecast is scheduled for April 30th.
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We saw lots of evidence of loose snow avalanches from the past few days in Turnagain Pass, but did not see any recent slab avalanches. The light was fairly flat throughout the day so it was not the best conditions for avalanche spectating. We saw many avalanches from the last few days that released naturally in steep rocky areas and caused large loose snow avalanches that entrained a fair bit of snow on their way down the mountain. This type of avalanche was observed in the majority of areas with sustained steep terrain, regardless of aspect.
Example of a long running wet loose avalanche from earlier this week that entrained enough new snow on the way down to create a large debris pile. Photo 4.13.22
|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|
A little bit of new snow overnight coupled with sustained winds at 10-15 mph with gusts to 25 mph are forming fresh wind slabs up to a foot deep that will be likely for human triggering today. In areas closer to Prince William Sound, like Portage and Placer, the new snow could add up to 6-12″ today which will create larger wind slabs up to 2′ deep. The most likely place to find these fresh wind slabs will be along upper elevation ridgelines and cross loaded gullies. Looking for signs of active wind loading, stepping off the beaten path to check for hollow feeling wind transported snow, and using test slopes to check for shooting cracks are all good ways to identify areas with sensitive wind slabs. The new snow fell onto a melt freeze crust in most locations so wind slabs might not bond well with the old snow surface and avalanches could run further than normal thanks to the firm bed surface.
In areas that saw more new snow earlier this week, like Portage and Placer, today’s new snow and wind could cause larger avalanches to release back down to the old snow interface 1-3′ deep. This seems unlikely due to the melt freeze crusts in the upper snowpack, but we have a fair bit of uncertainty right now due to sparse field observations and the fact that the recent storms heavily favored parts of the forecast zone near Portage and Placer. In addition there is an older weak layer from mid-March that we are still tracking (see additional concern).
Despite the cloudy skies and temperatures staying close to freezing yesterday there was still enough energy from the sun to melt surface crusts up to roughly 2000′. This made for much improved skiing and riding conditions at lower elevations in the afternoon and could also make wet loose avalanches possible later in the day. In addition the warm temps and wind could cause cornices and glide cracks to be more likely to fail.
1-2″ thick supportable crust on the surface in the morning that, surprisingly, melted up to 2000′ in the afternoon despite cloudy skies and temperatures barely above freezing. Photo 4.13.23
A weak layer of facets buried about 3-6′ deep in the snowpack is still on our radar due to widespread very large avalanche activity on this layer in the second half of March. It has been two weeks since we have seen any avalanche activity on this layer and we think it is very unlikely for a human triggered or natural avalanche. However, due to the consequences of being involved with an avalanche this size we are still keeping track of it.
Snowpack structure showing upper ‘crust sandwich’ and deeper buried weak layer from mid-March. Photo 4.13.23
Yesterday: Broken sky cover to start out the day shifting to overcast by around noon. Light snow started around noon with little accumulation during the day. Winds moderate at 5-15 mph with gusts up to 25 mph. Temperatures stayed fairly warm at lower elevations, hovering around 32 F up to 2000′ throughout the day. At upper elevations temperatures stayed closer to 20 F throughout the day.
Today: Light snowfall and cloudy skies are expected to continue today, with around 2-3″ of snow accumulation in Turnagain and Girdwood and up to 6-12″ in areas closer to Prince William Sound like Portage and Placer. Moderate E winds in the 10-20 mph range will continue throughout the day with stronger gusts at upper elevations. Temperatures are expected to warm up again today with snowline reaching up to 700′ in the afternoon.
Tomorrow: The snow is expected to taper off Friday evening and the winds will gradually decrease overnight. Cloudy skies are still expected during the day Saturday, but no new snow and decreased wind speeds in the 0-10 mph range. Temperatures will climb a little bit higher Saturday afternoon with highs in the 30s F above 3000′.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||31||2||0.1||94|
|Summit Lake (1400′)||31||0||0||46|
|Alyeska Mid (1700′)||30||2||0.1||89|
|Bear Valley – Portage (132′)||33||5||0.35||–|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||24||SE||7||14|
|05/22/23||Turnagain||Avalanche: Tincan||Nick D'Alessio|
|05/12/23||Turnagain||Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit||Heather Thamm|
|05/07/23||Turnagain||Observation: Tincan – Bear Tracks||CNFAIC Staff|
|05/05/23||Turnagain||Observation: Seattle Ridge||AS/ WW Forecaster|
|05/02/23||Turnagain||Observation: Cornbiscuit||Schauer/ Sturgess Forecaster|
|05/02/23||Turnagain||Observation: Seward Hwy Turnagain Pass||Joel Curtis|
|04/30/23||Turnagain||Observation: Magnum||Ayla, Kit Crosby, Barton|
|04/29/23||Turnagain||Observation: Tincan||John Sykes|
|04/28/23||Turnagain||Avalanche: Taylor Pass/Pastoral||Schauer/ Creighton Forecaster|
|04/28/23||Turnagain||Avalanche: Tincan||Andy Moderow|
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: email@example.com
|Area||Status||Weather & Riding Conditions|
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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.