Hatcher Pass Avalanche Center
Hatcher Pass

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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sat, December 3rd, 2022 - 7:00AM
Expires
Sun, December 4th, 2022 - 7:00AM
Forecaster
Allie Barker
Avalanche risk The Bottom Line

It will be possible to human trigger a persistent slab 1 to 3 ft thick on all aspects at mid and upper elevation today.

It will be possible to human trigger small dry loose sluffs in steep terrain 40° and steeper on all aspects, at all elevations.

Natural avalanches are unlikely.

Coverage is still thin and getting caught in any size avalanche could have severe consequences.

We recommend sticking to the rock skis/board for a little while longer.

 

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Sat, December 3rd, 2022
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
2,500'-3,500'
2 - Moderate
Avalanche risk
Low Elevation
Below 2,500'
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

No slab avalanches have been observed or reported since 11/16.

Numerous natural and human triggered small dry loose sluffs were observed on Friday 12/2.

12.2 Marmot- Dry Loose, W 4000′

 

12.2 Eldorado- Dry Loose E/SE 3600′

 

12.2 Skyscraper- Dry Loose S/SE 4000′

 

12.2 Martin Mine- Dry Loose, S/SW 4200′

Avalanche Problem 1
  • 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

Persistent slabs, 1 to 3 ft thick, will be possible to human trigger in isolated locations, on all aspects, at mid and upper elevation.  It will be unlikely to trigger an avalanche below 2500′ because the snowpack is shallower. Natural avalanches are unlikely.

3-4″ of low density new snow on Thursday was not enough to cover old tracks but has improved riding conditions.

Thankfully, the Matanuska wind did not build wind slabs as expected on Thursday afternoon, allowing us to continue on a track towards improving stability in the snowpack.

The good news is that no one has triggered an avalanche since Nov 16th and a lot of people have been getting out. The bad news is we still have very poor structure and flaws in our snowpack which are producing unstable results with snow pit tests. This points to the lingering possibility of human-triggering a full-depth slab avalanche at or near the ground.

We are still getting propagation in our pits.

Whumphing is a red flag for this avalanche problem, along with shooting cracks and recent avalanches.

Continue to use safe travel protocol in avalanche terrain:

  • SPREAD OUT when ascending.
  • Descend ONE at a time and regroup in identified safe zones.
  • Avoid riding above or near cliffs, rocks, gullies or other hazards.
  • As always, carry a transceiver, probe, and shovel, and know how to use them!
Avalanche Problem 2
  • Dry Loose
    Dry Loose
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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

It will be possible to human-trigger Thursday’s 3 to 4 inches of new snow on slopes 40º and steeper on all aspects, at all elevations. Natural avalanches are unlikely.

While avalanche size will be small, getting caught in a loose dry avalanche in steep terrain that funnels into any terrain trap has the potential to increase the consequences.

12.2 Skyscraper Human triggered and Natural Dry loose, NE 4500′

Weather
Sat, December 3rd, 2022

NWS AVG Forecast here.

NWS point forecast here.

Marmot Weather Station here.

Independence Mine Snotel here.

State Parks Snow Report and Motorized Access information here.

Observations
Recent Observations for Hatcher Pass