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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, March 11th, 2019 - 7:00AM
Expires
Tue, March 12th, 2019 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

The avalanche danger is  CONSIDERABLE  today.  Human triggered slab avalanches 2-3′ thick are likely on steep slopes and may be triggered remotely.  Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Give cornices a wide berth and watch for wet snow moving in low elevation terrain.  

SUMMIT LAKE:   Despite only a few inches of new snow, this area has a very shallow and weak snowpack. Strong winds may have overload buried weak layers and caution is advised if heading to this area.

LOST LAKE:    Caution is advised in the Seward region. New snow and wind have created dangerous avalanche conditions. Large human triggered avalanches should be expected in this zone as well.

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Mon, March 11th, 2019
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
Considerable (3)
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
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

Likelihood of Avalanches
This graphic depicts how likely you are to trigger avalanches or encounter natural avalanches while traveling on avalanche prone slopes. Unlikely means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. The chance of triggering or observing avalanches increases as we move up the scale. Certain means that humans will be able to trigger avalanches on many slopes, and natural avalanches should be expected.

Size of Avalanches
This graphic depicts the potential size and destructive force of expected avalanches. Small avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become large enough to bury, injure, or kill people, large enough to bury or destroy vehicles and break a few trees, and large enough to destroy railway cars, buildings, or a substantial amount of forest. Historic avalanches are massive events capable of destroying villages and gouging or altering the landscape.
More info at Avalanche.org

Triggering a large storm slab avalanche is still likely on steep slopes today and extra caution is advised. The snowpack still needs time to adjust to the recent load. The storm over the weekend brought 2-3 feet of snow and winds gusting above 100 mph. The snow fell on a variety of old snow surfaces including crusts, surface hoar and facets. There were a few natural avalanches that occurred during the storm reported yesterday. Observers in a couple of locations found the new snow bonding fairly well but overall there is still the potential for a large avalanche to be triggered. A few large whumpfs were experienced by groups in Turnagain and Summit Lake yesterday. Continued warm temperatures that can help the new snow bond to the old snow may first make the storm slab more cohesive and avalanches could be larger and more connected today. Wind-loaded areas are most suspect. High winds and heavy snow tend to make slabs lower down on the slope than expected, watch for pillowed areas and unusual loading.  The winds also created some mid-storm layers that were reactive and noted in observations. As temperatures rose yesterday the snow became wetter and heavier at lower elevations. Roller balls and wet sluffs/push-a-lanches may be possible today in steep low elevation terrain as there was no freeze overnight near sea level. Steer clear of cornices and choose terrain carefully. It may not be the first skier or snowmachine on the slope that triggers the avalanche and there is still the potential to trigger an avalanche remotely. 

Storm snow at 1500′ on Tincan yesterday. There was propagation at the new/old snow (small facets) interface, 3-10-19.

 Obvious wind-loading and cornice growth in Hippy Bowl, 3-10-19. 

 

Weather
Mon, March 11th, 2019

Yesterday: Broken skies, light rain/snow showers and easterly winds 10-20 mph with gusts into the 30s and 40s, easing off a bit mid-morning. Temperatures were in the 20Fs to mid 30Fs. Overnight mostly cloudy skies and easterly winds in the teens gusting to 30 mph. Temperatures stayed in the 20Fs and 30Fs.  

Today: Mostly cloudy skies with temperatures in the high 20Fs to high 30Fs. Snow and rain showers are forecast with a couple of inches of snow expected and rain/snow line around 1000 ft. Winds will be southerly 10-15 mph with gusts into the 20s and 30s. Temperatures look to cool overnight dropping into the teens and 20s.  

Tomorrow: Partly sunny with temperatures in the 20Fs and 30Fs. Chance of snow showers later in the day.   Light winds increasing overnight into Wednesday. The next storm looks to impact the area Wednesday evening.  

*Seattle Ridge wind sensor is not reporting.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  32 0    0 70  
Summit Lake (1400′)  33  0      0 27
Alyeska Mid (1700′)  32  0      0.25  71

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 23   NE    15 49  
Seattle Ridge (2400′) 28   *N/A   *N/A   *N/A  
Observations
Recent Observations for Turnagain Pass
Date Region Location
12/10/19 Turnagain Avalanche: Tincan and Sunburst from the air
12/10/19 Turnagain Observation: Tincan
12/08/19 Turnagain Avalanche: Tincan
12/06/19 Turnagain Avalanche: Sunburst
12/04/19 Turnagain Observation: Sunburst
12/03/19 Turnagain Observation: Hippy Bowl
12/01/19 Turnagain Observation: Tincan, All elevations
12/01/19 Turnagain Observation: Tincan
11/30/19 Turnagain Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge
11/29/19 Turnagain Observation: Sunburst Ob #2
Riding Areas
Updated Wed, December 11th, 2019

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.
Placer River
Closed
Closed.
Skookum Drainage
Closed
Closed.
Turnagain Pass
Closed
Closed.
Twentymile
Closed
Closed.
Seward District
Carter Lake
Closed
Closed.
Lost Lake Trail
Closed
Closed.
Primrose Trail
Closed
Closed.
Resurrection Pass Trail
Closed
Closed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor
Closed
Closed.
South Fork Snow River Corridor
Closed
Closed.
Summit Lake
Closed
Closed.

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