Sat, March 26, 2016 Turnagain Pass Avalanche Forecast

Sat, March 26th, 2016

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Considerable (3)

Below Treeline
Below 1,000'

No Rating (0)

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

Glide Avalanches

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

More info at Avalanche.org

The snowpack continues to fall apart at the ground. Yesterday, another large glide crack released on the face of Seattle Ridge. If you are headed to Turnagain Pass this weekend you can’t miss it, it’s front and center, just across from the motorized parking lot. If you have not been to the ‘Pass’ for a while, you may be surprised at how many cracks litter the mid-elevations and how many of these have released. It goes without saying, staying out from under glide cracks is HIGHLY recommended!

*With the unseasonably warm temperatures over the past week, the springtime melt-down (or shed-cycle) is closing in upon us. We do have cooler temperatures for today, and likely tonight, that will form surface crusts as high as 2,500′, but it is good to remember that undreneath the pack is very wet and unsupportable at these mid-elevations. This ‘rotten’ soft snow, so to speak, is a red flag for not only the glide problem but for the potential for large wet slab and wet loose avalanches.

Wet Loose Slides today? Southerly slopes seing direct sunlight may warm enough to melt the surface crust. In this case, wet loose slides could be triggered by people. Keep tabs on the surface conditions.

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

At elevations above 3,000′ (above the majority of the glide crack/avalanche hazard) fairly dry snow exists. There was roughly 2-5″ of new snow yesterday which sits on a mixture of old loose snow and old sun and wind crusts. Shallow wind slabs composed of mostly the new snow likely formed on leeward slopes during yesterday’s moderate Easterly winds. These slabs should be ~6-8″ thick and in pockets along ridgelines. Quick hand pits and watching the surface texture for smooth rounded wind pillows and drifts will help to find any relatively new wind slabs.

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

With a chance for direct sunshine today (and tomorrow) watch for cornices to weaken and possibly fall naturally. We have not seen much cornice failure recently but we do know these large features will begin to start calving soon. Limiting and avoiding time under cornices will be key as we head into springtime hazards.

If skies clear for travel above treeline, take stock of the slope or couloir you wish to ride/ski – is there a large cornice looming over you while you ascend/descend?

Weather

Sat, March 26th, 2016

Yesterday’s weather consisted of overcast skies with some light precipitation in the morning hours. Around .5″ of rain fell up to 2,000′ and between 2-5″ of snow fell above 2,000′. Ridgetop winds were moderate, averaging to 20mph with gusts to 40mph from a generally East direction. Temperatures were in the mid-30’s at 1,000′ and upper 20’s at 3,000′. Overnight, winds have died down substantially and temperatures have cooled off several degrees and move into a break between storms.

For today, we are expecting partly cloudy skies, which could become quite clear by noon before a chance more clouds might move in later today (tough sky cover forecast). No precipitation is expected and winds are slated to be light to moderate from a Northerly direction, averaging 5-15mph. Temperatures should begin to climb again today as the sun comes out and reach up to 40F at 1,000′.

Sunday looks to be nice: mostly clear skies and light Northerly winds as a quick high pressure ridge builds before another low pressure system moves in Sunday night.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	32	rain	0.5	124
Summit Lake (1400′)	35	rain	0.3	41
Alyeska Mid (1700′)	33	rain	0.3	105

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	24	NE	11	40
Seattle Ridge (2400′)	27	SE	12	23

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/28/22	Turnagain	Avalanche: Turnagain Pass – late May wet slab cycle	CNFAIC Staff
05/21/22	Turnagain	Avalanche: Magnum, Lipps and Tincan	CNFAIC Staff
05/17/22	Turnagain	Avalanche: Sunburst	CNFAIC Staff
05/17/22	Turnagain	Observation: Tincan Ridge	Joe Kurtak
05/11/22	Turnagain	Avalanche: Cornbiscuit and Magnum west faces	CNFAIC Staff Forecaster
05/07/22	Turnagain	Observation: Granddaddy	Kit Barton
04/29/22	Turnagain	Observation: Sunburst wx station	AS/ MM/ AM/ NH
04/28/22	Turnagain	Observation: More Turnagain Pass/Summit Lake wet slab activity	Alex Marienthal
04/27/22	Turnagain	Observation: Magnum	Sykes / Buttrick Forecaster
04/27/22	Turnagain	Observation: Girdwood/Summit/Turnagain Road obs	A S

Riding Areas

Updated Wed, June 01st, 2022

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 as of May 1 per Forest Plan.
Placer River	Closed	Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage	Closed	Closed as of April 1st per Forest Plan.
Turnagain Pass	Closed	Closed as of June 1st.
Twentymile	Closed	Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake	Closed	Closed as of May 1 per Forest Plan.
Lost Lake Trail	Closed	Closed as of May 1 per Forest Plan.
Primrose Trail	Closed	Closed as of May 1 per Forest Plan.
Resurrection Pass Trail	Closed	Closed as of May 1 per Forest Plan.
Snug Harbor	Closed	Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor	Closed	Closed as of May 1 per Forest Plan.
Summit Lake	Closed	Closed as of May 1 per Forest Plan.