Sat, March 07, 2015 Turnagain Pass Avalanche Forecast

Sat, March 7th, 2015

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

Storm Slabs

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

More info at Avalanche.org

Issues directly related to new storm snow will be at the forefront of our avalanche concerns today.

4” of snow overnight combined with another 3-4” today will help to build small slabs in the Alpine. These slabs will be thicker on leeward slopes and require terrain at least 35 degrees in steepness to trigger. Bonding of these slabs will be generally good as the current storm progression is going from warm to cold, laying down “right side up” slabs. The exception to this will be in isolated pockets on steep leeward slopes. It is in this terrain where wind slabs could become as thick as 10” by the end of the day. Avoid slabs in this terrain that sound hollow, are “punchy”, or produce shooting cracks.

Low volume sluffing will be possible in very steep terrain (over 40 degrees). These should be slow moving and easy to avoid. Sluffs will be dry above 3,000’ and gradually more damp as you lose elevation. Heightened awareness of sluffing will be important when traveling above or towards terrain traps such as gullies, cliffs and trees.

Avalanche Problem 2

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

Weak layers buried 1-2’ deep seem to be dormant for the most part around Turnagain Pass. More uncertainty exists in the Girdwood Valley where we have less information about this layer. Yesterday my partner and I had a good look at the late January facet layer in steep Alpine terrain and found it to be unreactive. Testing over the past week has been consistent with what we found. New snow will not be enough of a load to awake this layer today. However, the possibility still exists to trigger slabs in the 2 foot range in isolated pockets in very steep (over 40 degrees) terrain. Focused assessment of this layer will be important if you find yourself venturing into steep Alpine terrain.

Weather

Sat, March 7th, 2015

Warm air continued its chokehold on the region over the past 24 hours. Temperatures have begun to dip slightly in the early morning hours with freezing levels around 1,000′. Moisture associated with a large system moving in from the Southwest has brought light amounts of snow with the Center Ridge SNOTEL recording 4 €/.4 H20 and Alyeska Midway station with 3.7 €/.3 €H20. Ridgetop winds have been light to moderate out of the East.

Today we can expect to squeeze another 3-4 € of snow/.3 € of H20 out of this system. Ridegtop winds will be out of the Southeast at 15 to 20 mph. Rain/snow line will be around the 1,000′ level and slowly drop to 500′ by the evening hours.

The extended outlook is showing a gradual clearing and cooling trend. Precipitation will linger through the weekend with clear skies and daytime highs in the teens by the beginning of next week.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	33	4	.4	44
Summit Lake (1400′)	36	trace	.1	7
Alyeska Mid (1700′)	34	4	.3	25

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	26	E	10	31
Seattle Ridge (2400′)	27	n/a	16	32

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.