Wed, January 27, 2021 Turnagain Pass Avalanche Forecast

Wed, January 27th, 2021

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Low (1)

Below Treeline
Below 1,000'

Low (1)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Low (1)
Below Treeline Below 1,000'		Low (1)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Recent Avalanches

A skier triggered a wind slab avalanche in the Library yesterday. The slide took out a portion of the existing skin track while a second group was ascending, but luckily nobody was caught in the avalanche. See report HERE.

Skier-triggered wind slab avalanche in the Library yesterday, 01.26.2021. Photo from anonymous observer.

Avalanche Problem 1

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

We will have one more day of relatively quiet weather before the next round of precipitation moves in later tonight, and the avalanche conditions have not changed much over the past few days. There is still a possibility of triggering wind slab avalanches in steep, wind-exposed terrain. Increasing cloud cover may make larger objectives a bit more challenging today, but if you are planning on moving into bigger terrain, it will be important to identify and avoid wind-loaded slopes. Watch for visual clues of recent wind loading, like stiffer snow at the surface, smooth pillows of wind-drifted snow, or various wind-textured surfaces. Avoid steep terrain if you notice any clear indicators of instability such as shooting cracks, collapsing, or recent avalanche activity. The most likely places to find unstable snow will be just below ridgelines, or on convexities or cross-loaded gullies in alpine areas. This could be in areas like upper elevations on the skier side of the pass, the Seattle Ridge back bowls, or at higher elevations in the Girdwood valley.

Stay tuned for the forecast over the next few days– it is looking like we are headed back into an active weather pattern towards the end of the week.

Cornices: If you are traveling along ridgelines, be sure to keep plenty of distance from the edge of the large cornices that have developed throughout the area. These things have a nasty tendency to break much further back than one would expect, and they are ready to fail under the weight of a snowmachine or a skier. It is also important to minimize time spent traveling below cornices, as there is a chance they could fail naturally.

Sluffs: There has been plenty of dry loose activity as folks have been accessing steeper terrain during these past few days of clear weather. We expect more of the same today on steep slopes. While it is unlikely a sluff would bury a person, they are getting plenty big enough to have serious consequences if they carry you over cliffs, rocks, or through trees.

Large cornices above Hippy Bowl, with chunks breaking off recently. Photo: Eric Roberts. 01.26.2021

Additional Concern

Glide Avalanches

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

More info at Avalanche.org

We have recently seen glide cracks open and release in the Girdwood valley, Turnagain and Summit Lake areas. These avalanches are unpredictable and large since they involve the entire snowpack. Let us know if you see any other cracks or releases, and be sure to avoid getting on or below slopes where you see them open up.

Weather

Wed, January 27th, 2021

Yesterday: Temperatures were in the upper teens to low 20’s F under clear skies with valley fog lingering all day. Winds were blowing 5-10 mph out of the west at ridgetops.

Today: Clouds are expected to begin to move in today as the high pressure ridge we have been enjoying gives way to a low pressure system moving in tonight. Temperatures will be in the mid teens to low 20’s during the day, and climb steadily to the upper teens to mid 20’s tonight. Easterly ridgetop winds will stay light, blowing at 5-10 mph.

Tomorrow: There is a chance for light snowfall tonight, which could bring 2-4″ snow. Temperatures should be cold enough to bring snow down to sea level, with highs in the low to mid- 20’s F. Easterly winds are expected to pick up to 15-25 mph at the ridgetops, with gusts to 30 mph.

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

	Temp Avg (F)	Snow Depth (in)
Center Ridge (1880′)	10	126
Summit Lake (1400′)	3	43
Alyeska Mid (1700′)	14	111

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	16	W	7	17
Seattle Ridge (2400′)	11	NE	3	8

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
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

Riding Areas

Updated Sat, September 23rd, 2023

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 per Chugach National Forest plan December 1. Subject to adequate snow cover.
Placer River	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Skookum Drainage	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Turnagain Pass	Closed	Scheduled opening on the Wednesday before Thanksgiving per Chugach National Forest plan. Subject to adequate snow cover.
Twentymile	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Seward District
Carter Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Lost Lake Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Primrose Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Resurrection Pass Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Snug Harbor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
South Fork Snow River Corridor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Summit Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.