Mon, March 02, 2015 Turnagain Pass Avalanche Forecast

Mon, March 2nd, 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

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

Triggering a slab 2’ thick is becoming more difficult and less likely with time. In the last few days snowpack observations have revealed a weak layer of buried facets to be thinner and less reactive. The slab sitting on this weak layer also seems to be settling out and is not as thick and strong as it was a week ago in many places.

With that said propagation potential does still exist and triggering a slab avalanche is possible on slopes steeper than 35°. This problem will be more likely on Southern aspects where a sun crust/facet combo can been found. There is also elevated concern in the 2600-3000’ elevation band where this facet layer is sitting on top of a stout crust.

Triggering a slab will be more likely in these specific places. Avoid thin areas around rocks or steep rollovers on well-connected slopes steeper than 35°. Obvious clues such as collapsing/woomphing may not be present. A larger trigger, such as several people on a slope, may be just enough to initiate a slab in motion. Be sure to practice safe travel habits. Identify safe spots, move between islands of safety one at a time, and always have an escape zone in mind.

In areas such as Girdwood and above 4000’ in Turnagain Pass more uncertainty exists due to lack of information about these zones.

Moderate winds have eroded many ridgetops back to the “anti-tracks” created over two weeks ago making it easier to stay off of the slab in the Alpine.

Avalanche Problem 2

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

Today Northeast winds are expected to increase to 20-35 mph this afternoon along ridgetops. Only a trace of new snow is expected this afternoon and there is currently not a lot of snow available for transport. If winds increase as forecasted small pockets of isolated wind slabs, 4-6” are possible on leeward terrain features.

Weather

Mon, March 2nd, 2015

Yesterday a dense valley fog remained along Turnagain Arm, but in Turnagain Pass skies were clear and sunny. Temperatures were in the 20’s F in the morning and reached the high 30’s F in the afternoon along ridgetops. Light winds 5-10mph from the Southwest kept surface snow conditions cool throughout the day.

Temperatures remained warm overnight, in the low 30’s F along ridgetops. Winds were light, averaging 10-20 mph from the East. No new precipitation was recorded in the last 24 hours.

A trace of new snow is expected this afternoon at higher elevations and light rain at sea level. Temperatures will remain warm in the low-mid 30’s F. Ridgetop winds from the North will be in the 20-35mph range. This evening precipitation and winds are expected to increase. Winds could be as high as 45 mph along ridgetops with up to 5 € of snow at higher elevations. Rain/snow line will be around 1000′.

Winds look to be backing off by late evening. Tomorrow more of the same is expected. Warm temps in the 30’s F with rain at sea level and up to a few inches of snow at higer elevations.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	30	0	0	40
Summit Lake (1400′)	24	0	0	6
Alyeska Mid (1700′)	30	0	0	23

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	31	E	8	32
Seattle Ridge (2400′)	28	NW	10	33

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.