Sun, January 24, 2021 Turnagain Pass Avalanche Forecast

Sun, January 24th, 2021

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Low (1)

Alpine Above 2,500'		Considerable (3)
Treeline 1,000'-2,500'		Moderate (2)
Below Treeline Below 1,000'		Low (1)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Recent Avalanches

Tincan: Skiers reported sensitive storm slabs on short, steep terrain in the Tincan trees yesterday, which were very sensitive to ski cuts.

Skier-triggered storm slab release in the Tincan trees yesterday. That new snow is being drifted into sensitive wind slabs today. Photo: Matti Silta. 01.23.2021

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

After another round of strong winds and heavy snowfall yesterday, and continued winds through today, it is likely a person could trigger an avalanche 1-2’ deep on wind-loaded slopes. As visibility improves through the day, it will once again be possible to travel into higher elevations where it will be most likely to encounter fresh wind slabs. Luckily, there are some clues that can help you identify fresh wind loading:

Cracks shooting out from your snowmachine or skis, or the whumpf of the snowpack collapsing under your weight.
A ‘punchy’ feeling slab of stiff snow over weaker snow.
Smooth, rounded ‘pillows’ of dense snow.
Relatively firm snow at the surface.

Today it will be important to avoid steep slopes with any of these characteristics. Winds are expected to continue to be strong enough to blow snow around, and wind slabs will continue to be sensitive through the day. Yesterday’s strong easterly winds have shifted overnight and are now blowing out of the northwest, which means we will likely find fresh wind slabs on multiple aspects. Winds will not be as strong at mid- and low- elevations, making conditions less dangerous as you decrease in elevation.

Heavy snowfall and strong winds yesterday while we were riding and digging pits around Seattle Ridge. 01.23.2021

Cornices: The recent strong winds and wet snow have been ideal for building large cornices. We saw multiple natural cornice failures as the skies cleared following Monday’s storm, and we are expecting to see more of the same today. Cornices have a bad reputation for breaking much farther back than one would expect. If you find yourself traveling along ridgelines as skies begin to clear today, be sure to give them plenty of space. It will also be important to minimize the amount of time spent traveling under large cornices, as they can release naturally and unexpectedly.

Evidence of a large cornice fall above PMS bowl during the 1/18 storm. Similar activity is expected today. 01.19.2021.

In addition to these wind-related issues, we are also tracking a crust buried 1.5-2′ deep. We have gotten poor test results on weak snow associated with this crust on Cornbiscuit and just north of the Seattle Ridge uptrack. At this point, the layer is not giving us enough to concern to adjust our terrain use, but it is something we are paying attention to. If you get out and have any observations related to this layer, we’d love to hear about it.

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 are continuing to track the glide cracks opening up around the area. It is nearly impossible to predict when these cracks will release as large avalanches, so it is important to avoid spending near them or below them. So far, we have seen reports of recent glide activity at the following locations:

Girdwood Valley: Goat shoulder, Raggedtop lower SE shoulder, the far NE end of Penguin Ridge above Girdwood.

Turnagain Pass: The far northern end and SE aspect of Seattle Ridge, Warmup Bowl (-1 Bowl) NE aspect on the backside of Seattle Ridge.

Summit Lake: Gilpatrick’s S face, Devil’s Creek south side.

Weather

Sun, January 24th, 2021

Yesterday: A warm storm brought 1-1.5” water, with mostly rain below 1000’, and 6-10” snow at elevations above 1500’. Ridgetop winds were out of the east at 30-50 mph, and high temperatures were in the upper 20’s F at upper elevations and in the mid-30’s F at lower elevations.

Today: Winds have shifted and are now blowing out of the northwest, which will continue through the day, with ridgetop speeds expected to be around 20-25 mph. There is a chance of light snowfall this morning, but skies will clear up through the day, with partly sunny skies expected by this afternoon. Temperatures this morning are in the low 20’s to low 30’s F, and are expected to decline through the day and into tonight, reaching the high teens to high 20’s F overnight. We may see some lingering valley fog as skies clear and colder air moves in this afternoon.

Tomorrow: Skies will continue to clear up overnight, with mostly sunny skies on tap for tomorrow. Light easterly winds are expected to be around 5-10 mph, and high temperatures will be in the upper teens to low 20’s F.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	32	9	0.6	135
Summit Lake (1400′)	32	0	0.1	45
Alyeska Mid (1700′)	31	5	1.05	116

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	23	NE	23	72
Seattle Ridge (2400′)	27	SE*	14*	35*

*Seattle Ridge anemometer has been rimed over and not reporting since 5 p.m. yesterday.

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 Thu, June 01st, 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	Closed May 15.
Placer River	Closed	Closed May 15.
Skookum Drainage	Closed	Will close to motorized use on April 1, 2023 per the National Forest Plan.
Turnagain Pass	Closed	Will close on June 1.
Twentymile	Closed	Scheduled closure May 1.
Seward District
Carter Lake	Closed	Scheduled closure May 1.
Lost Lake Trail	Closed	Scheduled closure May 1.
Primrose Trail	Closed	Scheduled closure May 1.
Resurrection Pass Trail	Closed	Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor	Closed	Extended opening until May 15.
South Fork Snow River Corridor	Closed	Scheduled closure May 1.
Summit Lake	Closed	Scheduled closure May 1.