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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, April 26th, 2016 - 7:00AM
Expires
Wed, April 27th, 2016 - 7:00AM
Forecaster
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

The avalanche danger is CONSIDERABLE  today. Glide avalanches continue to release daily in popular recreation areas.  Avoid being under the runout of glide cracks.  Human triggered and natural wet loose avalanches are possible in steep terrain due to saturated snow, rain and warm temperatures. In the Alpine new snow and strong winds have formed wind slabs and added stress to already large cornices.  

*ATTENTION HIKERS:  Summer use areas crossing under avalanche terrain should be avoided due to the possibility of natural avalanche activity. Byron trail in Portage Valley and Crow Pass are two examples of trails with dangerous avalanche terrain above.

AVALANCHE OUTLOOK for Wednesday, April 27th:  

Continued CONSIDERABLE danger is anticipated for Wednesday due to rain/snow, strong winds, and warm temperatures. Remember this means natural avalanches are possible and human triggered avalanches are likely. If the precipitation is heavier than forecasted or the sun comes out for an extended period of time the danger may increase to HIGH.

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Tue, April 26th, 2016
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Considerable (3)
Below Treeline
Below 1,000'
Avalanche risk
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
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 wet spring storm that is impacting our area has added almost 2″ of rain to an already wet snowpack. As the snowpack gets warmer and more saturated below 2500′ the already active glide avalanche cycle may ramp up even more. An additional glide avalanche ran over the uptrack on Seattle Ridge and another piece of the crack on the West face of Magnum also released. Watch for new cracks appearing and avoid travel under existing glide cracks.

 

 

West face of Magnum with recent wet loose avalanches and a new glide release adjacent to the one from last week. 

New glide avalanche on the Seattle Ridge uptrack (farthest right streak).

Avalanche Problem 2
  • Wet Loose
    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

Turnagain Pass received almost 2″ of water yesterday and another .5″ is forecasted to fall today. The rain is falling onto an already wet snowpack. Human triggered wet loose avalanches are likely below 2500′ and natural ones are possible. Skiers reported triggering a small wet loose avalanche on Sunday. Visibility was limited yesterday but new wet loose avalanches were observed on the West face of Magnum. We have yet to see surface slides gouging into deeper layers but this potential may increase. As the rain/snowline dances around 2500′ rain may fall onto snow and trigger wet loose avalanches as well. We will continue to monitor whether or not the rain is impacting the drier snow in the Alpine. If you are traveling through the glop today pay attention to how deeply you are penetrating into the snowpack, watch for roller balls and remember loose avalanches can knock you off your feet, are hard to escape and can push you into terrain traps. 

Wet day at Turnagain Pass

Additional Concern
  • Wind Slabs
    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

Temperatures at 3000′ have remained below freezing which means the rain falling at the road will have been snow in the Alpine. We suspect 6-12″ have fallen in the past 24 hrs. This combined with the sustained 30-40 mph winds may have formed tender wind slabs along ridgelines. Look for drifted snow and watch for cracking underfoot. The wind and snow may also have added stress to very large cornices. Avoid travel on or under these beasts. 

Weather
Tue, April 26th, 2016

Yesterday was overcast and rain fell throughout the day (snow above 2500′?). Temperatures were in the high 30Fs at 1000′ and the high 20Fs at 3000′. Easterly winds were steady 30-40mph with gusting into the 80s.

Today will be mostly cloudy with another .5″ of rain forecasted to fall.  Winds will be easterly 15-35 mph potentially increasing in the afternoon.  Temperatures will be in the low 30Fs to low 40Fs depending on elevation.  

Tomorrow looks to be similar and to quote the National Weather Service, “NO BIG CHANGES IN THE WEATHER FOR THE EXTENDED PERIOD. WEDNESDAY  EVENING AND THURSDAY FEATURE AN EXTENSION OF THE CURRENT WEATHER  PATTERN.”

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 37   0   1.8   104  
Summit Lake (1400′)  41 0  0  15
Alyeska Mid (1700′)  36 0    .8  87

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  28  ENE  33  89
Seattle Ridge (2400′)  30  ESE  25    60  
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Riding Areas
Updated Tue, April 20th, 2021

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
Open
No parking in turnaround at end of the road near the outhouse.
Placer River
Open
Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
Skookum Drainage
Closed
The Skookum Valley is closed to snowmachines. This closure occurs annually on April 1 as per the CNF Forest Plan.
Turnagain Pass
Open
Twentymile
Closed
Seward District
Carter Lake
Open
Lost Lake Trail
Open
Primrose Trail
Open
Resurrection Pass Trail
Closed
Closed for the 2020/21 winter season.
Snug Harbor
Open
South Fork Snow River Corridor
Open
Summit Lake
Open

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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.