Sun, December 20, 2020 Turnagain Pass Avalanche Forecast

Sun, December 20th, 2020

Alpine
Above 2,500'

Low (1)

Treeline
1,000'-2,500'

Low (1)

Below Treeline
Below 1,000'

Low (1)

Alpine Above 2,500'		Low (1)
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)

Avalanche Problem 1

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

It has now been over a week since our last reported avalanches (more details here and here), and over two weeks since we have seen an avalanche big enough to bury a person. For the past week, we have gotten a steady trickle of low density snow with light winds, which is a great way to maintain quality riding conditions and improve stability. But, this doesn’t mean we can turn off our avalanche brains! For now, avalanches are unlikely, not impossible. Keep a few things in mind when you are out today:

Isolated wind slabs: There may be isolated pockets of wind loaded snow lurking below ridgetops and in cross-loaded gullies that could still fail today. Pay attention to warning signs like shooting cracks and whumpfing if you plan to move into steep terrain today.
Loose snow avalanches: Or, more commonly referred to as sluffs. Skiers near Magnum noted loose snow avalanches running long distances on Friday, and it will be possible to see more of the same today.
Cornices: As always, give cornices plenty of space, they often break back farther than you would expect.

If you are moving into steeper terrain today, be sure to only expose one person at a time to steep slopes, watch your partners from safe spots well out of the way of avalanche paths and runout zones, and be mindful of other groups traveling above and below you.

Although unlikely, it is not impossible to find isolated wind slabs like this one (which happened over a week ago) near ridge tops and in cross-loaded gullies. Eddies. Photo: Kakiko Ramos-Leon. 12.12.2020.

Additional Concern

Deep Persistent Slabs

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

More info at Avalanche.org

We know there is weak snow at the base of the snowpack throughout the advisory area, but it is quite variable and has shown signs of gaining strength. With no activity in this layer in over two weeks, very few signs indicating instability, and no significant loading in over a week, it is becoming very unlikely to trigger an avalanche deep in the snowpack. This layer is more concerning in areas with thinner snowpack such as Crow Pass, and as you head south from Turnagain Pass (Lynx Creek, Silvertip) towards Summit Lake. This type of avalanche is tricky. Deeply buried weak layers can often lay dormant for weeks or longer without showing any signs of activity before somebody finds just the wrong spot to trigger one. If you want to avoid problem entirely, you can stay off steep, rocky, slopes over 35 degrees.

Weather

Sun, December 20th, 2020

Yesterday: The mountains received 2″ new snow at the weather stations, with higher totals at upper elevations. Light winds around 5-10 mph at the ridgetops shifted from easterly to westerly yesterday afternoon. Temperatures dropped through the day, with morning temperatures starting the day in the mid- 20’s F and dropping to the mid teens F at lower elevations and dropping from the high teens to low teens F at upper elevations.

Today: We are expecting another quiet day weather-wise, with no snow accumulation under mostly sunny skies and westerly winds blowing 5-10 mph at the ridgetops. Temperatures should remain cool, with highs in the mid teens F at upper elevations, and low 20’s at lower elevations, and lows tonight around 10 F at upper elevations and low teens at lower elevations.

Tomorrow: Easterly winds are expected to pick up to 20 mph at the ridgetops in the afternoon, along with an increasing chance for precipitation as the next storm moves in. High temperatures should be in the low 20’s F at upper elevations and mid-20’s at low elevations. The National Weather Service has issued a High Wind Watch and a Winter Storm Watch for Monday evening through Tuesday evening. Stay tuned as the next storm develops, it looks like things could get spicy!

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	19	1	0.2	60
Summit Lake (1400′)	18	2	0.2	27
Alyeska Mid (1700′)	17	2	0.2	62

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	14	N	9	25
Seattle Ridge (2400′)	17	N	12	3

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.