Sat, April 16, 2016 Turnagain Pass Avalanche Forecast

Sat, April 16th, 2016

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

3 - Considerable

Below Treeline

Below 1,000'

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


Travel Advice	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches	Natural and human-triggered avalanches unlikely.	Natural avalanches unlikely; human-triggered avalanches possible.	Natural avalanches possible; human-triggered avalanches likely.	Natural avalanches likely; human-triggered avalanches very likely.	Natural and human-triggered avalanches certain.
Avalanche Size and Distribution	Small avalanches in isolated areas or extreme terrain.	Small avalanches in specific areas; or large avalanches in isolated areas.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.	Large avalanches in many areas; or very large avalanches in specific areas.	Very large avalanches in many areas.

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

Yesterday’s hampered visibility limited some information regarding new glide avalanche activity, however, we were able to get a look at Seattle Ridge and a few other areas along the Seward Highway. New avalanche activity seen yesterday:

New glide avalanches:
– Paths off of Pk 4940, across from the Granite Ck Campground (South facing, photo below)
– Penguin Ridge (South facing)
– Eddies (South facing)

*Note: no new glide releases were noted on Seattle Ridge

New wet avalanches:
– Wet loose avalanche above Bertha Creek Campground @ 3:30 yesterday
– Small wet loose slides and roller balls seen on Pete’s South, Southerly aspect

This current wet snowpack, combined with today’s weather (light rain, cloudy and possible sun), has us prepared for another round of glide activity. Our message remains the same: to avoid being under glide cracks and respective runout zones. To be in the wrong place at the wrong time when a glide releases could likely be deadly. Considering the motorized up-track is threatened by cracks, we are recommending that people do not travel on the up-track or in runout areas along Seattle Ridge. Glide avalanche hazard also exists on the non-motorized side of Turnagain Pass in certain zones, most pronounced on Southerly aspects.

Left photo: New glide releases on South facing Pk 4940. Right photo: Glide releases on Seattle Ridge and a melting out snowpack.

Close up view of the Seattle Ridge snowmachine up-track. Several cracks threaten the route along with remnants of a natural wet loose avalanche that occurred Thursday (4/14)

Avalanche Problem 2

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

Yesterday temperatures rose to 32F at 2,500′ and light rain and cloud cover since has likely kept the mid-elevation surface wet and unsupportable. It was no surprise to hear of a natural wet loose avalanche witnessed on a SE facing slope above the Bertha Ck Campground. These wet loose slides will be a concern again today with our warm temperatures. Any periods of sunshine will also be a factor and increase the chances for natural activity. Natural wet loose avalanches are possible on all aspects at elevations below 2,500′ and human triggered wet loose sides are likely. In the Alpine, Human triggered wet sluffs are possible on slopes seeing warming by the sun.

*Remember wet loose avalanches can be hard to escape once initiated and particularly hazardous if they push you into a terrain trap.

Additional Concern

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

At elevations above 2,500′ and in the Alpine the snowpack is generally stable. There are a few things to watch for if skies open enough for travel to the upper elevations:

– Lingering wind slabs that could be triggered in steep rocky terrain

– Cornice falls (we have yet to see cornices start falling in the Alpine but this could happen any day with our warm temps)

– Wet sluffs on steep solar aspects

Weather

Sat, April 16th, 2016

Yesterday’s weather consisted of mostly cloudy skies and occasional light precipitation. Past 24-hour accumulations were up to 0.2″ of rain up to 2,500′ with 1-2″ of wet snow above this. Areas on the South side of Turnagain Pass and Girdwood Valley saw only a trace. Ridgetop winds have been moderate, averaging 10-15mph with gusts to the 20’s from the East. Temperatures rose to the low 40’sF at 1,000′ yesterday (32F at 2,500′) before cooling off to the mid 30’s at 1,000′ (upper 20’s at 2,500′).

For today, partly cloudy skies and intermittent rain showers are possible (trace of snow above 2,200′) adding only 0.1″ of water. It’s possibly the sun could come out later in the day. Ridgetop winds will be ~10mph from the East while temperatures stay warm (rising to 45F at 1,000′ and 32F at 2,500′).

Sunday looks to be a short break between low-pressure systems that are churing in the Gulf. We could see sunshine along with high clouds and light winds. Another bout of moist Southerly flow looks to move in on Monday.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	36	rain	0.2	111
Summit Lake (1400′)	37	0	0	28
Alyeska Mid (1700′)	37	0	0.03	96

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	28	NE	12	28
Seattle Ridge (2400′)	30	SE	12	24

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
10/27/24	Turnagain	Observation: Tincan	Michael Kerst
10/21/24	Turnagain	Observation: Turnagain Pass Road Observation	Trevor Clayton
10/19/24	Turnagain	Observation: Tincan – Below Todds Run	Andy Moderow
10/18/24	Turnagain	Observation: Taylor Pass	Eli Neuffer
10/15/24	Turnagain	Observation: Tincan Common	John Sykes Forecaster
10/14/24	Turnagain	Avalanche: Tincan	CNFAC Staff
05/13/24	Turnagain	Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South	H Thamm
05/13/24	Turnagain	Observation: Turnagain Pass non-motorized side	Amy Holman
05/12/24	Turnagain	Observation: Warm up Bowl	Tony Naciuk
05/07/24	Turnagain	Observation: Turnagain Pass Wet Slabs	A S

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