Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, January 29th, 2022 - 7:00AM
Expires
Sun, January 30th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is CONSIDERABLE above 1,000′ on all aspects. Yesterday’s heavier than predicted snowfall with last night’s strong winds will keep all storm snow avalanche problems in the forecast. Wind slabs will be the most likely to trigger and could be over 3′ in depth. It will also be possible to trigger storm slabs (1-2′ deep) and sluffs in the new snow. Cornices have grown, we need to give them an extra wide berth and limit time under them. A cautious mindset is key as the skies start to clear and we head into the mountains. Pay close attention to any signs of instability, including recent avalanches.

The danger is MODERATE below 1,000′, where it will be possible to trigger an avalanche 1-2′ deep in the storm snow.

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Sat, January 29th, 2022
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
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
Considerable (3)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Recent Avalanches

There were only a couple reports from the mountains during the storm yesterday, one was from John Sykes (forecaster) at Pete’s South and the other from a group in Placer Valley. Both parties reported storm slab avalanches that were easy to trigger. They stayed in the trees due to the stormy weather and avalanche concerns, but in the smaller terrain they could trigger slabs up to a foot deep at Pete’s South and over 2′ deep in Placer Valley where more snow has fallen.

Small storm slab avalanche on Pete’s South. Slab was skier triggered at 1700′ on a west aspect, about 12″ deep and 50′ wide. 1.28.22.

Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    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

Wow, what a few days of snowfall. Light to heavy snow has been falling since Wednesday afternoon with the highest rates seen yesterday. Snowfall totals over the past 24-hours were 18-24″ for mid/upper elevations in Girdwood and Placer Valleys and 12-14″ for Turnagain Pass. Check out the table below for the storm totals since Wednesday. Ridgetop winds have been fairly moderate out of the east until last night when they took a jump for 6-8 hours blowing 40-50mph with gusts over 70mph. All this new snow with those winds last night will keep storm snow avalanche issues front and center, especially wind slabs!

Storm total estimates for 2,500′ beginning Wednesday afternoon through last night:

Turnagain Pass:  14-22″  (1.4″ SWE at Center Ridge 1,800′)
Girdwood Valley:  24-36+”  (2-3″ SWE)
Placer Valley:  24-36+” (~3″ SWE)
Summit Lake:  2-4″  (0.2 SWE)

For all those headed out today- the storm has just ended. We need to ease into terrain and not let powder fever get the best of us. Be sure to pay close attention to slopes with recent avalanches, and the other signs of instability (cracking in the snow around you and whumpfing). The deeper the new snow, the larger the potential avalanche. Safe travel practices are a must. Expose only one person a time, watch your partners, and have escape routes planned. Although the storm snow should be in the process of stabilizing, it can take a couple days.

Wind Slabs:  These are likely to be easy to trigger and could be larger and more dangerous than expected. They could be anywhere from 1-3+ feet deep. Watch for signs of wind effect and steer clear of slopes and cross-loaded gullies with wind loading.

Storm Slabs:  It will still be possible to trigger storm slabs similar to those yesterday on slopes out of the wind, including slopes in the trees. Storm slabs could be 1-2′ deep depending on how much snow fell in the area you are in. There is crust up to ~2,000′ under the new snow and this could slow the bonding in the mid-elevations.

Sluffs (loose snow avalanches):  On slopes out of the wind, expect to trigger sluffs in the new snow. These could entrain a large amount of snow in larger terrain.

Cornices:  Be extra cautious on ridgelines as cornices could be teetering on the brink of failure. They could trigger an avalanche below and potentially put others in harms way.

 

Cracking on a small test slope yesterday on Pete’s South. 1.28.22.

 

Persistent Slab:  In addition to the storm snow avalanche concerns, there is an outside chance that a person could trigger a larger avalanche on weak snow near the New Year’s crust. This would now be buried 2-6+′ deep. This is a tricky problem with high uncertainty and low likelihood. The only known activity on this layer was a large human-triggered avalanche on Tincan Proper over a week ago (details here). As we head into a clear period and the storm snow stabilizes, we need to keep this issue in our minds.

Weather
Sat, January 29th, 2022

Yesterday:  Moderate to heavy snowfall across the forecast area. Girdwood/Placer/Portage Valleys saw the higher past 24-hour accumulations of 18-24″. Turnagain Pass was closer to 12-14″. Rain snow line crept up to 200-300′ overnight. Ridgetop winds were easterly, 20-25mph during the day and reaching 40-50mph around midnight with stronger gusts. Temperatures hovered in the 20’sF at the mid and upper elevations with sea level creeping into the mid 30’sF.

Today:  The stormy weather is pushing out this morning and there is a chance for some clearing skies. A trace to no precipitation is forecast. Ridgetop winds have quieted down as well and slated to be 5-10mph out of the northwest today. Temperatures are in the 20’sF at most locations with lower elevations close to 30F.

Tomorrow:  Mostly clear skies are expected for tomorrow and Monday with this break in storms. Ridgetop winds look to be light and variable. Temperatures should be cooling off to the teens and single digits in valley bottoms.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 31 13 0.8 98
Summit Lake (1400′) 26 0 0 35
Alyeska Mid (1700′) 30 18 1.2 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 23 NE 28 72
Seattle Ridge (2400′) 26 SE 8 20
Observations
Recent Observations for Turnagain Pass
Date Region Location
11/25/22 Turnagain Observation: Sunburst
11/25/22 Turnagain Observation: Sunnyside / Seattle Ridge
11/25/22 Turnagain Observation: Sunburst
11/25/22 Turnagain Observation: Tincan Trees
11/25/22 Turnagain Observation: Tincan
11/25/22 Turnagain Observation: Top of Seattle Ridge uptrack
11/24/22 Turnagain Avalanche: Sunnyside/Main Bowl
11/23/22 Turnagain Avalanche: Seattle Ridge
11/23/22 Turnagain Observation: Tincan Trees
11/23/22 Turnagain Observation: Tin Can Common Bowl
Riding Areas
Updated Sat, November 26th, 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
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Placer River
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Skookum Drainage
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Turnagain Pass
Closed
The Forest has issued a closure order for Turnagain Pass due to inadequate snow cover for resource protection. Conditions will be monitored daily. Between 16-20” of snow exists at the parking lot. The scheduled opening would have been the Wednesday before Thanksgiving per Forest Plan.
Twentymile
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Seward District
Carter Lake
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Lost Lake Trail
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Primrose Trail
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
South Fork Snow River Corridor
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Summit Lake
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.

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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.