Sun, January 19, 2014 Turnagain Pass Avalanche Forecast

Sun, January 19th, 2014

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Considerable (3)

Below Treeline
Below 1,000'

Considerable (3)

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

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

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

This storm pushed us into a deep slab problem at higher elevations. This means that we now have average slab depths of greater than 1 meter sitting on top of a persistent weak layer. The avalanche implications are the same as we’ve been seeing, but the volume and destructive force have increased.

With deep slab concerns a backcountry traveler will probably not see obvious signs of instabilty (whumphing, shooting cracks) until the slab actually avalanches. It is unlikely to be triggered at the deep points, but rather at the thinner edges near scoured ridges or exposed rocks. It may propagate large distances where it then pulls the deeper pockets. It may allow multiple tracks before somebody finds the trigger point and avalanches the entire slope.

Deep slab is a low probability, high consequence problem. With continued precipitation, warm temperatures, and high wind – steep terrain should be avoided. When active weather abates the safe terrain options will get better with time.

This photo is on Moose mountain, above Canyon creek.

Avalanche Problem 2

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

Below 2000 feet we had significant rain on snow on Friday. We can expect more rain today, perhaps as high as 1200 feet. The photos below show an example of the abnormal avalanche activity that can happen with rain and warm temperatures. This is fairly low in the Tincan trees. 3 distinct pockets released sympathetically on the steeper rolls as the weak layer collapsed. Debris from this was very dense.

Tincan avalanche 1550 ft elevation. 200 feet high by 1000 feet wide. 2-3 feet deep.

Weather

Sun, January 19th, 2014

Friday’s storm deposited over 2 feet of snow at high elevations and over 3 inches of rain or snow water equivalent at some low elevations. Saturday gave us a break in the storm, but temperatures did not drop significantly.

Today, more rain and snow is expected. Another pulse of moisture is approaching from the south, originating at a deep 956mb low pressure center. Up to another inch of water is forecasted for the next 24 hours, with the bulk of that precipitation happening tonight. Temperatures will increase throughout the day, and snow level will rise from 500 feet to 1200 feet. Look for a southeast wind 51-74 mph, also increasing slightly as the day progresses.

Expect continued warm temperatures through the week with more rain and snow possible.

Current satellite image.

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 Mon, May 15th, 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	Open	Chugach NF staff will be assessing daily after May 15th. Please keep machines on the snow and avoid brown spots to keep this area open as long as possible.
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.