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ARCHIVED - Forecasts expire after 24 hours.
Issued
Mon, January 17th, 2022 - 7:00AM
Expires
Tue, January 18th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is MODERATE on all aspects above 1,000′. It remains possible that a person could trigger an older wind slab avalanche on slopes with prior wind loading. Wind slabs are in the 1-2′ thick realm and could be fairly stiff. Triggering a larger slab avalanche breaking near crusts 2-4+’ deep is becoming less likely, however, we should keep this potential in our minds when stepping into bigger terrain. Additionally, cornices are large and these could fail under the weight of a person, as occurred yesterday.

A LOW danger exists below 1,000′ where triggering an avalanches is unlikely.

Special Announcements

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The domain chugachavalanche.org is down due to a migration with the parent organization eNom. Please message avalanche center staff on Facebook or Instagram, or at the email wendy.wagner@usda.gov.

Mon, January 17th, 2022
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. Dangerous avalanche conditions. 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

There was a very close call with a skier taking a fall with a large cornice break yesterday on Gold Pan peak (behind Magnum Ridge) – photos below. Please take a minute to read the two reports HERE and HERE. We are grateful to these skiers for sharing their story and so glad the skier who was carried 1,000′ down the slope was uninjured.

There was also a report of a wide skier triggered wind slab around 4,400′ just northwest of the Girdwood Valley. It was reported to be 300′ wide and up to 2′ deep. No one caught.

Series of photos from the cornice break on Gold Pan Peak yesterday. Photos:Neil Gotschall, 1.16.22.

Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
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.

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

There was quite a bit of traffic in the mountains yesterday and we received 11 observations from different groups – thank you! Many folks were finding a stable snowpack, but there were a few that did not. These unstable areas were mostly in the Alpine zone around 4,000′ and higher and associated with wind loading from last week’s stormy weather. With another fairly quiet day weather-wise, we can expect similar conditions today.

Wind slab avalanches and cornice breaks appear to be our greatest concern. There was a party in the high terrain around Girdwood that had two large collapses (whumpfs) along a ridge, one of which triggered a series of cracks on a fairly low angle slope below them. See the photos below. This slope had significant wind loading and was able to produce cracks all the way over to the slope next to it. It is unknown what the wind slab was sitting on, but either way, it’s a clear sign to be very suspect of any slope with signs of loading.

Crack that was triggered by skier 50′ away from the ridge when the skiers felt a large whumpf. Photo: George C., 1.16.22.

 

Cracks can also be seen on the adjacent slope. Photo: George C., 1.16.22.

Along with looking for wind loading, be sure to listen for any whumpfing, watch for any cracks that shoot out from you and generally stiffer snow over softer snow. There could be wind slabs lurking in cross-loaded gullies and lower on slopes just over rollovers.

Cornices:  As advised by the party that experiences the cornice fall yesterday, give these features a wider berth than you might think. They have grown considerably during last week and there could be other cornices that just need a bit more weight to fall.

Avalanche Problem 2
  • Persistent Slabs
    Persistent Slabs
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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

Buried under last week’s storm snow is the New Year’s crust (anywhere from 2-5′ deep depending on location). There are also a few other crusts that formed during the stormy weather last week at elevations around 1800′ and below. We’ve been tracking the snow around these crusts to see if avalanches could break in areas that have not seen wind loading but do have a buried weakness.

The good news is, the snow around these crusts is generally getting harder and becoming more stable. That said, it doesn’t mean we can forget about them. Especially as we venture into bigger terrain. There could be an outlier and hence keeping to our safe travel practices, communicating with our partners and understanding the consequences if an avalanche occurs are good ways to stack the odds in our favor.

 

A look at the snowpack on Cornbiscuit – a thinner snowpack area. Photo:AAS Rec Level 1, 1.16.22.

Weather
Mon, January 17th, 2022

Yesterday:  Mostly clear skies were over the region. Ridgetop winds were light from the NW (5-10mph) with gusts in the teens. Temperatures dropped during the day into the teens at most locations.

Today:  Partly cloudy skies with some sunshine is forecast. Ridgetop winds are turning southerly today, yet expected to remain light (5-10mph). Temperatures are in the teens F at most elevations with some valley bottoms in the single digits this morning. A few degrees of warming is likely through the day.

Tomorrow:  Cloudy skies with a chance for an inch or two of snowfall is expected tomorrow as a weak weather system moves in. Ridgetop winds will turn easterly and should increase into the 15-20mph. Another few inches is possible on Wednesday, with snow to sea level as temperatures remain in the 20’sF.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 17 0 0 78
Summit Lake (1400′) 6 0 0 29
Alyeska Mid (1700′) 18 0 0 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 12 W 5 13
Seattle Ridge (2400′) 13 N/A* N/A* N/A*

*Seattle Ridge weather station wind sensor is rimed over and not recording data.

Observations
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Date Region Location
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11/12/23 Turnagain Avalanche: Goldpan – avalanche
11/11/23 Turnagain Observation: Tincan Common
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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.