Mon, April 06, 2015 Turnagain Pass Avalanche Forecast

Mon, April 6th, 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

Wind Slabs

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.

More info at Avalanche.org

Winds will move around the 3-6” of loose snow that is currently sitting in the higher elevations. Slabs will build as thick as 1 foot on leeward slopes in the Alpine. With more snow available for transport in the Girdwood Valley expect slabs to be thicker there than on Turnagain Pass. Another 2+” of snow falling today will help to slightly increase the size of wind slabs. These slabs will be most sensitive as they are forming. Be on the lookout for snow that is stiff, feels upside down or produces shooting cracks. These slabs will exist in small pockets and will become more of an issue if triggered above terrain traps or on large steep (>40º) slopes.

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

Steep north facing slopes in the Alpine have a setup that hold the potential for large avalanches 2-3’ deep to release under the weight of a person or group. This concern reared its ugly head last week and has since quieted down. Despite the lack of activity on these deeper layers over the weekend, it is still worth keeping in mind that there exist pockets of dense slab sitting on layers of weak faceted snow. If you find yourself in steep North facing terrain make sure you take precautions to minimize your exposure – travel one at a time, identify escape routes and communicate your decisions and plans well within your group.

Additional Concern

Dry Loose

Dry Loose

Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

More info at Avalanche.org

If visibility improves enough for travel in the Alpine, expect terrain sheltered from the wind to have enough loose surface snow to produce low to medium volume sluffs. This will be a minor issue, but like wind slabs will become more serious when travelling above terrain traps such as cliffs, gullies and trees.

Weather

Mon, April 6th, 2015

Over the past 24 hours temps have remained mild with averages in the mid 20s F at ridgetops and low 40s F at sea level. Precipitation in the form of snow fell yesterday morning with Girdwood Valley receiving 3 € and Turnagain Pass picking up just a trace. Winds were generally light but have picked up into the 20 mph range this morning at ridgetop level.

Today a mix of snow and rain will fall as a large and broad low pressure system moves in from the Bering Sea. Accumulation will be light during the day with up to 2 € expected. Rain/snow line will be around 1,500′. Ridgetop winds will be moderate, in the 15-25 mph range out of the East. Temps will climb into the low 30s F at ridgetops.

The system responsible for stormy weather today will pick up in intensity tonight and into tomorrow. Snow accumulation will be in the 8-10 € range in the higher elevations by tomorrow morning.

Looking further out we can expect a continuation of unsettled weather through the middle part of the week with generally light precipitation through Wednesday.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	33	trace	0	58
Summit Lake (1400′)	34	0	0	10
Alyeska Mid (1700′)	33	3	.25	33

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	23	ENE	12	35
Seattle Ridge (2400′)	25	n/a	17	39

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.