Tue, December 23, 2014 Turnagain Pass Avalanche Forecast

Tue, December 23rd, 2014

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Low (1)

Below Treeline
Below 1,000'

No Rating (0)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Low (1)
Below Treeline Below 1,000'		No Rating (0)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

Persistent Slabs

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

More info at Avalanche.org

Our current problem can be described as low probability/ high consequence. The likelihood of waking up this documented layer of buried surface hoar that we’ve been talking about the last few days is waning as time ticks by and temperatures drop. However if one were to find the right trigger point (shallow areas in the slab or slope convexities are the likely areas) on a slope the resulting avalanche could be quite large. We have a hard time classifying this type of problem using the North American Avalanche Danger Scale because it doesn’t totally capture this low likelihood/ high consequence scenario with any one color.

Colors aside, it’ll be important today to travel through the backcountry with heightened awareness. Ensure good spacing between parties and individuals when ascending steep terrain; one person at a time on the slope; plan out and communicate escape routes and safety zones; ensure safe zones are safe. Keep in mind that with this avalanche problem, potential exists for a slope to avalanche wall-to-wall or even connect slopes through shallow bands of rock.

As mentioned in the bottom line, this is a “scary” MODERATE avalanche problem and though our snowpack is gaining strength, surface hoar once buried accounts for more avalanche accidents than any other weak layer.

Weather

Tue, December 23rd, 2014

Calm weather dominated the eastern Turnagain arm zone yesterday. After a light morning drizzle deposited a very thin crust on the snow surface up to about 1,500′ the skies began to break and visibility improve. Ridgetop winds were in the single digits from the east with temperatures hovering around 32 degrees at 1,000′.

We may continue to see a few snow showers through the day as instability in our region weakens with an advancing ridge moving in from the west. This will shift winds to a northwesterly direction where we may see gusts into the mid-teens or low 20’s mph today. Temperatures at 1,000′ will linger right around the freezing mark. We may also see fog development today and into tomorrow-in low-lying areas around the highway.

Looking out toward Xmas it appears that south-central AK will be influenced by westerly flow as a dominant low-pressure system in the western Aleutians tracks east toward the mainland. Expect temperatures to slowly decline and periods of light snow thru the holiday.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	29	1	.1	28
Summit Lake (1400′)	24	0	0	4
Alyeska Mid (1700′)	32	1	.1	21

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	24	E	6	14
Seattle Ridge (2400′)	26	N/A	N/A	N/A

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.