Tue, February 10, 2015 Turnagain Pass Avalanche Forecast

Tue, February 10th, 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

After a long three week dry spell, we finally got a fresh coat of paint yesterday with a bit more on the way today and tomorrow. Normally, we wouldn’t bat an eye at a couple inches of fluffy stuff here and an inch there – but not this season! Snowfall totals from around the region yesterday were: (keep in mind this is VERY low density snow)

10″ in Portage Valley (see photo below)
5″ at Turnagain Pass North side (Eddies)
3-4″ at Turnagain Pass (Sunburst)
1-2″ at Turnagain Pass Southern side (Johnson Pass trailhead)
3″ in Girdwood Valley
1″ at Summit Lake

WIND SLABS
Unfortunately, the winds picked up last night from the East and will continue to blow today in the moderate range (15-25mph). This is prime wind loading speed and slab development for areas with new snow. Slabs will be forming on very weak faceted (sugary) snow and expect them to be touchy and easy to trigger. However, they should be quite shallow and soft, only packing a real punch in areas with 4-5″ of new snow where slabs could be up to 10″ thick – these areas of course are where many of us will seek out. The best clues to watch for will be: winds actively loading slopes, stiff feeling snow and cracks shooting from your skis/board.

SOFT SLABS from Warming Temperatures:
Along with the winds forming slabs, warming temperatures will also encourage the new snow to become more cohesive and ‘slabby’. In areas with over a few inches of new snow (such as Eddies Ridge), watch for shallow soft slabs, as the new snow overlies very weak snow.

Avalanche Problem 2

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

With varying amounts of new snow sitting on pre-existing loose faceted snow, you can bet sluffs will be easy to trigger on slopes over 40 degrees. These will be higher volume than we have seen and fast enough to catch you if you’re not careful. At the mid-elevations where a crust sits under the loose snow, expect sluffs to be faster than in the higher elevations.

Portage Valley ice climbers:
Wind and warming temperatures could cause natural small avalanches in yesterday’s snow to flush through gullies and over climbing routes. Heads up!

Yes, it is true, 10″ of snow in the Portage Valley (photo: Graham Predeger)

Weather

Tue, February 10th, 2015

During the past 24-hours we have seen mostly overcast skies with a few flakes adding a trace of snow. Ridgetop winds have been slowly increasing from a generally Easterly direction overnight, averaging ~20mph with gusts into the 30’s. Seattle Ridge is blowing from the South, which is uncommon for this main flow direction. Temperatures have been climbing as well and the longtime inversion is scouring out quickly – valley bottoms are ~30F while ridgetops are ~20F this morning.

Today we can expect overcast skies and light snow showers to add up to an inch or two. Winds will be the main player as they are forecast to continue in the 15-25mph range from the East. Temperatures should remain near 20F on the ridgetops and the low 30’sF at sea level and valley bottoms.

Looking forward to Wednesday and Thursday, continued light snowfall is on tap. An embedded short wave associated with a large low pressure system South of the Alaska Peninsula should give us a couple inches each day. Warm air is also on tap… By Thursday we could see rain showers to sea level with a rain/snow line as high as 1,000′. Stay tuned.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	26	1	tr	33
Summit Lake (1400′)	23	1	0.1	8
Alyeska Mid (1700′)	26	1	0.9	23

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	18	E	12	33
Seattle Ridge (2400′)	21	SW	15	34

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.