Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, March 8th, 2022 - 7:00AM
Expires
Wed, March 9th, 2022 - 7:00AM
Forecaster
Andrew Schauer
Avalanche risk The Bottom Line

The avalanche danger is MODERATE above 1000′. It is possible a person can trigger an avalanche 1-3′ deep, with the snow from last week sitting on top of weak surfaces. We’ve seen this combination of a slab on top of a weak layer throughout the advisory area, so approach steep slopes with caution today. Be on the lookout for changing conditions as the next round of active weather moves in this afternoon. The danger is LOW below 1000′.

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Tue, March 8th, 2022
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Low (1)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

Here we are three days out from the last storm, and still concerned with how well the new snow is bonding to the old surfaces. This is because the latest storm buried a variety of weak surfaces including surface hoar, near-surface facets, and a crust. Unfortunately these weak surfaces are slow to heal, and we may be headed into persistent slab territory. Since the snow fell on Saturday, we’ve seen natural and human-triggered avalanches near Girdwood, Turnagain Pass, the Placer Valley, and the Lynx Creek area. Some of these have been quite large, and we’ve found surface hoar at the bed surface at every avalanche crown we’ve been able to visit- most recently at the crown of an avalanche above Main Bowl on Seattle Ridge that we looked at yesterday.

We’ve noticed some concerning patterns with the recent activity. There have been multiple avalanches where somebody triggered an avalanche after there were multiple sets of tracks on the slope. We’ve also gotten multiple reports of remotely triggered avalanches. As we move further out from the last major loading event, the weak layer is slowly becoming less reactive, but it is still possible to trigger an avalanche today.

This weak layer seems to be present at most places in our advisory area, but it isn’t everywhere. There have been quite a few people getting out into avalanche terrain without triggering an avalanche over the past few days. If you are trying to get into steep terrain today, be aware that you are taking on a fair amount of risk, and do your homework. Look out for the classic signs of unstable snow- shooting cracks, collapses, and fresh avalanche activity. Take the time to hop off your machine or step off the skin track and look for this weak layer. It is easily identified in a quick hand pit, and is only buried about a foot deep in most locations. If you notice any warning signs, or if you identify the weak layer, use that as a sign to back off your objective. If you feel confident in your snowpack assessment, cover your bases by only exposing one person at a time to avalanche terrain and watch your partners from safe spots. If you’d rather not roll the dice, you can avoid the risk by sticking to lower angle terrain.

Winds are expected to bump up slightly this afternoon as the next round of active weather approaches. Be on the lookout for changing conditions if the storm arrives sooner than expected, and stay tuned over the next couple days as the storm develops.

The buried surface hoar we are concerned with. This particular sample was the culprit from an avalanche at the top of Main Bowl on Seattle Ridge. 03.07.2022

Debris from a large avalanche in Warmup Bowl. That’s a person on a snowmachine on a bump just to the left of the debris pile along the shadow line for scale. 03.07.2022

Click here if the video from Seattle Ridge below does not load in your browser.

Weather
Tue, March 8th, 2022

Yesterday: Skies were partly cloudy with high temperatures in the upper 20’s to upper 30’s F. Winds were light at 5-15 mph out of the east with gusts of 20-30 mph. Temperatures got down to the mid 20’s overnight, with no precipitation in the past 24 hours.

Today: Cloud cover is increasing today as the next round of snow approaches tonight. Winds will pick up slightly, blowing 10-15 mph and gusting around 20 mph out of the east. High temperatures are looking to be in the mid 20’s to upper 30’s F, with lows dropping down to the upper teens to mid 20’s F. Light snow is expected to start around sunset tonight. No precipitation is expected during the day.

Tomorrow: Active weather returns tonight, with light snowfall throughout the area. Our forecast zone is looking to receive 1-2″ overnight tonight, with another 2-5″ tomorrow. Easterly winds will bump up a little bit more tomorrow, with sustained speeds of 15-25 mph and gusts around 25-35 mph. The rain level should stay down around 200-600′, with high temperatures in the mid 20’s to upper 30’s F.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 32 0 0 94
Summit Lake (1400′) 25 0 0 41
Alyeska Mid (1700′) 32 0 0 107

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 22 ENE 11 29
Seattle Ridge (2400′) 25 SE 11 20
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.