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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sat, January 20th, 2024 - 7:00AM
Expires
Sun, January 21st, 2024 - 7:00AM
Forecaster
John Sykes
Avalanche risk The Bottom Line

The avalanche danger is MODERATE above 1000′ today. Glide avalanches releasing down to the ground are the main concern. These avalanches release randomly and are very destructive. Keep an eye out for existing glide cracks on slopes above you and try to avoid spending time underneath. Otherwise, normal mountain hazards like cornices, dry loose avalanches, and small wind slabs in steep terrain are possible today. Below 1000′ the avalanche danger is LOW.

Special Announcements

Headed to Summit LakeSeward/Lost Lake, or the Chugach Front Range today? Check out our weekend outlooks for these areas in the ‘Forecast’ tab, which provide a summary of conditions over the past week and a preview of what to expect this weekend.

Sat, January 20th, 2024
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
Sun, January 21st, 2024
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
Sun, January 21st, 2024
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
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.
Recent Avalanches

We received a report of cornices failing naturally at upper elevations, where the combination of unseasonably warm temperatures in the 30s to 40s F and sunny skies are causing them to weaken. The large cornice failures triggered localized avalanches where they impacted the slope below, but did not propagate to adjacent areas. In addition in areas where there is wind sheltered soft snow on the surface, dry loose avalanches have been reported to be a significant concern in steep terrain.

Avalanche Problem 1
  • Glide Avalanches
    Glide Avalanches
  • Aspect/Elevation
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
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.

Aspect/Elevation of the Avalanche Problem
Specialists develop a graphic representation of the potential distribution of a particular avalanche problem across the topography. This aspect/elevation rose is used to indicate where the particular avalanche problem is thought to exist on all elevation aspects. Areas where the avalanche problem is thought to exist are colored grey, and it is less likely to be encountered in areas colored white.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "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. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word Size (D scale) Simple Descriptor
Small 1 Unlikely to bury a person
Large 2 Can bury a person
Very Large 3 Can destroy a house
Historic 4 & 5 Can destroy part or all of a village
More info at Avalanche.org

The potential for a glide crack to release and cause a very large avalanche involving the entire depth of the snowpack remains our primary concern today. Clear skies over the region should make it easier to identify existing glide cracks and minimize time spent underneath. Theses avalanches release at random times and can runout far into valley bottoms. We recommend avoiding them entirely if you can or travelling quickly while maintaining awareness of the slopes above if you can’t avoid travelling underneath.

In addition to glide avalanches we have received reports of cornices failing naturally. Cornices failures can be a significant hazard on their own, but they can also trigger avalanches on the slope below if there are any lingering instabilities that can be initiated by these massive triggers. Similar to glide avalanches, cornices can fail randomly and the best way to decrease your exposure to this hazard is to avoid spending time underneath large cornices. Especially if you note the temperatures are unusually warm and the sun is warming up the windward side of the cornice.

Finally, lingering wind slabs and dry loose avalanches could be a concern in steep terrain today. Small pockets of wind slab can linger on steep, unsupported features and cause small avalanches that can have large implications if you are in exposed terrain. Dry loose avalanches are also a concern if you are able to track down some wind sheltered soft snow on the surface. In steeper terrain these surface avalanches can pick up a head of steam and carry enough force to knock you off your feet. Best practice is to make a plan to manage your sluff before committing to steep terrain.

Keep an eye out for glide cracks like this and try to minimize time spent underneath. Photo from Sam McLain 1.18.24 

If you are gunning for steep terrain be aware of the potential for cornice failure, lingering small wind slabs, and dry loose avalanches (sluff). Photo from Nicholas Crews 1.19.24

Weather
Sat, January 20th, 2024

Yesterday:  Clear skies and light NE winds averaging 5-10 mph with gusts to 20 mph at upper elevations. Temperatures were in the single digits F at low elevations and low 30s F at upper elevations.

Today:  A high pressure ridge over the area will create continued clear skies and a lack of new snowfall throughout the region. For the first half of the day temperatures at low elevations are expected to remain in the single digits F and 20s to low 30s F at upper elevations. This afternoon the inversion is expected to become less dramatic, with temperatures at upper elevations decreasing into the teens F. Winds should remain light from variable directions with averages of 0-10 mph.

Tomorrow:  Sunday looks very similar to the past couple days, except with colder temperatures in the teens F at upper elevations. Winds are expected to remain light and variable with averages of 0-10 mph. No new snow expected.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 25 0 0 79
Summit Lake (1400′) 11 0 0 NA
Alyeska Mid (1700′) 24 0 0 78
Bear Valley – Portage (132′) 0 0 0
Grouse Ck – Seward (700′) 6 0 0 50

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 29 E 6 17
Seattle Ridge (2400′) 31 ESE 2 7
Observations
Recent Observations for Turnagain Pass
Date Region Location
02/24/24 Turnagain Observation: TinCan Backdoor/ Center Ridge
02/22/24 Turnagain Avalanche: Lynx Creek
02/22/24 Turnagain Observation: Turnagain, Seattle, Mt Ascension
02/21/24 Turnagain Observation: Tincan Trees
02/21/24 Turnagain Observation: Sunburst
02/20/24 Turnagain Avalanche: Tincan
02/20/24 Turnagain Observation: Seward Highway across from Johnson Pass TH
02/19/24 Turnagain Avalanche: Base of Seattle Ridge
02/18/24 Turnagain Observation: Lynx creek
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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.