Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sun, January 23rd, 2022 - 7:00AM
Expires
Mon, January 24th, 2022 - 7:00AM
Forecaster
Andrew Schauer
Avalanche risk The Bottom Line

The avalanche danger is CONSIDERABLE above 2500′, where it is likely a person can trigger an avalanche 1-2′ deep as strong winds continue to build sensitive slabs through the day. Winds are expected to increase steadily through the day as another storm approaches this evening. Expect to find dangerous conditions near ridgelines, convexities and gullies. Avalanche conditions are expected to become more dangerous as winds continue to pick up during the day.

The danger is MODERATE below 2500′, where slightly calmer winds will make wind slabs smaller and less reactive than in the upper elevations but it will still be possible to trigger an avalanche a foot deep or deeper on steep slopes that have seen recent wind loading. Be on the lookout for clear signs of poor stability like shooting cracks, collapsing, and fresh avalanche activity. There is wet snow at the surface up to around 2000′, which will make loose wet avalanches likely.

*Roof Avalanches: Continued above-freezing temperatures will make it likely we will see more roof avalanches today. These can be very dangerous, so be sure to keep an eye on children and pets, and be careful where you park your vehicles.

SEWARD/LOST LAKE: It is looking like the approaching storm is going to reach these areas before it hits our core advisory area. Be aware of increasing avalanche danger as wind, rain, and snow pick up this afternoon.

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Sun, January 23rd, 2022
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

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
More info at Avalanche.org

Wind slabs are once again our main concern, as winds ramp up during the day ahead of the next round of snow starting this evening. Winds are light out of the east as of 6:00 this morning, but are expected to to bump up to 20-30 mph with gusts of 30-50 mph by this afternoon. Although little or no snow accumulation is expected during the day, there is already plenty of soft snow on the ground that is ready to be drifted into sensitive wind slabs. The most likely place to find unstable snow will be on the usual suspects for wind slabs- steep slopes near ridgelines, convex rolls, and in gullies. Luckily this type of avalanche problem usually presents warning signs when conditions are unstable. Be on the lookout for shooting cracks, collapsing, and fresh avalanche activity as you travel today, and be cautious with your terrain choices as conditions are expected to become more reactive through the day. Yesterday I found reactive wind slabs on steep convexities in the Girdwood valley (details here), and similar activity is expected today. These avalanches will be most likely above 2000′, where most of the recent precipitation has been snow.

On some slopes there is a weak layer of snow sitting on top of the New Year’s crust, which was the culprit for a large human-triggered avalanche on Tincan Proper on Friday (more details here). This layer appears to be highly variable across the advisory area, but is somewhere around 2-3′ deep on the shallower end, and over 6′ deep in areas that saw the most snow over the past two weeks (Girdwood, Portage, Placer). The most likely place to run into trouble with this setup will be at higher elevations on slopes with a thinner slab sitting on top of the weak layer. It is possible an avalanche triggered near the surface could step down to this weak layer, resulting in a larger and more dangerous avalanche. Poor visibility and strong winds will make travel challenging in the alpine today, but if you are trying to get up high, this is the kind of setup that is worth looking out for. Be on the lookout for a stiff slab of snow sitting on top of weaker snow on top of the crust. This can be identified by digging a quick pit, probing with a pole as you travel, or hopping off your machine and looking for places where you can punch through relatively supportable snow in the upper 2-3′ of the snowpack. Ultimately, the best way to address higher uncertainty with a dangerous problem like this is to adjust your terrain choices, avoiding steep and consequential terrain until we have a better understanding of how this layer is behaving.

A strong system is approaching later this evening, bringing storm totals of 12-18″ by the end of the day tomorrow. It is looking like this storm is arriving late enough that it won’t increase the avalanche danger until late tonight, but be aware of increasing danger if the weather starts acting up earlier than expected. Tune in to tomorrow’s advisory for more details, and keep your fingers crossed for snow to sea level!

Cornices: Cornices continue to get larger and more sensitive as winds continue to blow snow off the ridgelines. These have a reputation for breaking farther back than expected, so be sure to keep a healthy distance from the edge as you travel along ridges. One group had a scary encounter with a cornice fall on Goldpan last Sunday (details here), and similar activity is possible today.

Loose Wet Avalanches: There is wet snow at the surface up to around 1800-2000′, which will make loose wet avalanches likely today. These are usually slow moving and on the smaller side, but they can have serious consequences if they carry you through dangerous terrain traps like trees, rocks, cliffs, or creeks. Be aware of this hazard as you travel around steep terrain in the mid and low elevations today.

Fresh wind slab release on a steep test slope at 2200′ on Notch Mtn., entraining loose wet snow as it slid. 01.22.2022

Rollerballs in the Tincan Trees yesterday, showing how wet the snow is at the surface. This snow is becoming wetter as above-freezing temperatures continue, making loose wet avalanches likely in steep terrain below 2000′. Photo: Adam Rothman, 01.22.2022.

Weather
Sun, January 23rd, 2022

Yesterday: High temperatures were in the upper 20’s to mid 30’s F, with rain up to 1600′ under cloudy skies. The mountains near Girdwood saw 0.3-0.6″ precipitation, which likely amounted to 3-6″ snow at upper elevations, and fell almost entirely as rain below 1500′. Turnagain Pass had periods of light rain, but weather stations did not measure any precipitation. Winds were 10-20 mph out of the east for most of the day, with a 5-hour period of 30-40 mph winds at the Sunburst station starting at 4 p.m.

Today: Easterly winds are expected to steadily increase during the day, with sustained speeds of 20-30 mph and gusts to 30-50 mph. Temperatures are expected to stay in the upper 20’s to low 30’s F. Light showers during the day are only expected to bring a trace to 2″ of snow, but heavy precipitation is expected to pick up this evening through tomorrow. The rain level is expected to start to drop later today, hopefully making it back down to 500′ before the precipitation starts. Overnight lows will hover in the upper 20’s to low 30’s F.

Tomorrow: Heavy snowfall is expected to continue overnight through tomorrow, with 12-18″ expected by the end of the day. Strong southeasterly winds will be around 20-30 mph with gusts of 40-50 mph. The rain line is expected to drop down to 200-500′ during the most intense period of the storm, and will rise back up to 1000′ as the strom finishes. As usual, heavier storm totals are expected in the Portage and Placer valleys.

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 35 0 0 81
Summit Lake (1400′) 31 0 0 30
Alyeska Mid (1700′) 33 1 0.4 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24 ENE 18 57
Seattle Ridge (2400′) 28 SE 15 30
Observations
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Riding Areas
Updated Fri, May 13th, 2022

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: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Closed as of May 1 per Forest Plan.
Placer River
Closed
Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage
Closed
Closed as of April 1st per Forest Plan.
Turnagain Pass
Open
Open. Extended opening through May 31.
Twentymile
Closed
Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake
Closed
Closed as of May 1 per Forest Plan.
Lost Lake Trail
Closed
Closed as of May 1 per Forest Plan.
Primrose Trail
Closed
Closed as of May 1 per Forest Plan.
Resurrection Pass Trail
Closed
Closed as of May 1 per Forest Plan.
Snug Harbor
Closed
Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor
Closed
Closed as of May 1 per Forest Plan.
Summit Lake
Closed
Closed as of May 1 per Forest Plan.

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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.