Sat, December 17, 2016 Turnagain Pass Avalanche Forecast

Sat, December 17th, 2016

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Moderate (2)

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

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

We have had very little snow so far in our upcoming week of stormy weather, but the snowpack is already showing its cards. Two shallow wind slabs were triggered yesterday by skiers/riders on Tincan and Eddies. These slabs were only 4-6″ thick, but are so touchy because they are sitting on VERY weak faceted snow. With another 2″ of new snow overnight and continued winds, we can expect today’s wind slabs to be a bit thicker – and just as touchy.

What to watch for today:

Look for areas where the winds have deposited snow
Watch for cracks in the snow that shoot out from your feet
Although slabs are thin and avalanches expected to be ‘low volume’ they can still pose a problem if you get knocked off your feet and sent into a terrain trap

Remember safe travel protocol: expose one person at a time, have an escape route planned, group up in safe zones and be aware of groups around you.

Photo below from Adam Rothman showing the shallow wind slab on Tincan. This is a classic slope for wind slab avalanches. Keep in mind, it has likely reloaded and could be ready for another release.

So what about this snowpack???

“This is a great layer for making avalanches.” Quote from Jim Kennedy, former Alyeska Snow Safety Director and current Alaska DOT Avalanche Program Director.

What Jim is talking about is the snow surface from our two-week cold and dry spell, shown in the video below. Faceted snow is notorious for causing avalanches once it is buried – this is the EXACT set-up we have now. With only 3-7″ of new snow causing low volume avalanches now, this is a pre-cursor to what is to come with additional snow in the forecast for tomorrow.

Weather

Sat, December 17th, 2016

Yesterday saw mostly cloudy skies with a few snow flurries. Ridgetop winds bumped up and averaged in the 20-25mph range with gusts to 51mph from a Southerly direction. Temperatures warmed to 36F at sea level (ugh….), to the upper 20’s at 1,000′ and low 20’sF on the ridgetops.

Overnight around 2″ of moist snow fell above 300′ with light rain/drizzle falling at sea level. The rain/snow line looks to be around 200-300′. Snow amounts overnight for Portage Valley and the higher elevations could be in the 4-6″ range. Today we should see cloudy skies and intermittent snow showers. Snowfall amounts during the day are expected to be anywhere from 0-2 inches. Ridgetop winds will be 5-10mph from a Southerly direction. Temperatures are expected to remain warm with a rain/snow line right around sea level.

The BIG news is how tomorrow’s storm is going to shape up. We are expecting winds in the 50-60mph range and snowfall in the 6″ to 1 foot range. Stay tuned on tomorrow’s advisory!!

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	28	2	0.2	23
Summit Lake (1400′)	29	0	0	9
Alyeska Mid (1700′)	29	2	0.25	14

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	22	21	NE	51
Seattle Ridge (2400′)	23	22	SE	48

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.