Sun, January 29, 2017 Turnagain Pass Avalanche Forecast

Sun, January 29th, 2017

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Low (1)

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

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

Cooling temperatures and clearing skies are a welcome relief to the overcast and low visibility conditions the past week. These better weather conditions will also allow for travel above treeline into the upper elevations – where the best powder exists from the past storms – this combination is our main concern at the avalanche center. Simply put, the snowpack is unstable in many areas and today could be a good day to get lured into steep avalanche terrain sporting good snow. What we have is a slab 2-4′ thick composed of last week’s storm snow (Jan 21 and Jan 26 storms). This slab sits on a variety of weak layers, most pronounced in the Girdwood Valley and the Southern end of Turnagain Pass, and further South. Several observers have noted widespread collapsing in the areas South of Turnagain Pass.

Careful snowpack evaluation is key today:

Listen for whumphing (collapsing of the slab)
Watch for cracks that shoot from your snowmachine, skis or snowboard
Do you see any recent avalanches?
Can you feel weak sugary snow when you step down with your boot? Possibly not if the slab is 2-3′ thick where you are
Is the snowpack thin in general?

These are all good questions to be asking yourself. Keep in mind, these signs may not be present, especially in areas well traveled prior to the storms, but don’t let that sway you into thinking the steeper slope next door and less traveled is safe. Today could be a tricky day to truly assess if a slope will slide or not. Due to the potential for large un-survivable avalanches, hedging your bets and sticking to mellow slopes is recommended.

A couple other points to consider:

Hand pits may not work as the slab is likely too thick
Slope cutting and ski cutting is not recommended as the slab may break above you
Remote triggering is possible (from below, mid-slope, adjacent to or from the ridgeline)

Low visibility and a thin snowpack exist on Magnum’s West face

Additional Concern

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

Cornices have grown substantially with the Jan 26 warm storm. These could be teetering on the balance and if one breaks, is likely to trigger a potentailly large slab avalanche below. Please be careful along ridgelines as a cornice break could not only take you down, but a subsequent avalanche could overrun someone below you.

Weather

Sun, January 29th, 2017

Yesterday’s weather consisted of overcast and obscured skies with light snow flurries. Snow accumulation was a trace to 3″ depending on locations. Temperatures continued to be warm, in the upper 20’s to 30F in most locations. Winds were light with gusts into the 20’smph from the Northwest.

Overnight, skies have cleared and temperatures have dropped dramatically with a cold Northwest flow over the region. Currently temperatures sit in the single digits above 3,000′ and in the teens below this, where they are expected to remain today. Ridgetop winds are, and will be, light to moderate from the Northwest (5-15mph) with gusts into the 20-30mph. There is no precipitation expected and skies should be partly sunny.

Tomorrow and Tuesday another system will move through bringing a chance for additional snow and warming temperatures before a possible dry spell for the later part of the work week. Stay tuned.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	21	2	0.1	62
Summit Lake (1400′)	17	0	0	26
Alyeska Mid (1700′)	21	trace	0.02	54

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	13	NW	5	24
Seattle Ridge (2400′)	15	Rimed	Rimed	Rimed

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 Sat, September 23rd, 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	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Placer River	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Skookum Drainage	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Turnagain Pass	Closed	Scheduled opening on the Wednesday before Thanksgiving per Chugach National Forest plan. Subject to adequate snow cover.
Twentymile	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Seward District
Carter Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Lost Lake Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Primrose Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Resurrection Pass Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Snug Harbor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
South Fork Snow River Corridor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Summit Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.