Hatcher Pass Avalanche Center

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ARCHIVED - Forecasts expire after 24 hours.
Issued
Thu, December 14th, 2023 - 7:00AM
Expires
Fri, December 15th, 2023 - 7:00AM
Forecaster
Allie Barker
Avalanche risk The Bottom Line

Small incremental loads over the past 5 days have brought 10 to 12 inches of new snow to Hatcher, significantly improving conditions.

A MODERATE hazard exists for human triggering small dry loose avalanches on all aspects on slopes 40° and steeper in specific locations. Natural avalanches are unlikely.

Rocks continue to lurk under the surface on southerly aspects.

Another pulse of snow is on the horizon for late Friday potentially bringing 6 to 9 inches of new snow.

 

Thu, December 14th, 2023
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
2,500'-3,500'
2 - Moderate
Avalanche risk
Low Elevation
Below 2,500'
2 - Moderate
Avalanche risk
Fri, December 15th, 2023
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
2,500'-3,500'
2 - Moderate
Avalanche risk
Low Elevation
Below 2,500'
2 - Moderate
Avalanche risk
Fri, December 15th, 2023
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
2,500'-3,500'
2 - Moderate
Avalanche risk
Low Elevation
Below 2,500'
2 - Moderate
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

Numerous dry loose (sluffs) were observed on Wednesday on all aspects on slopes steeper than 40º.  These likely occurred at/near the end of storm 12/12.

12.13 ESE 3800′ Skyscraper

A few older slab avalanches were observed Wednesday which likely occurred on 12/10-11. These were not visible earlier in the week due to poor visibility. The crowns are still visible but covered up with 4-8″ of new snow from the past few days.

12.13 Debris from slab avalanches and cornice fall, likely 12/10-11 funnel into the Death gully of Marmot

 

12.13 Another view of few day old slabs and cornice chunks, lookers right and left of the Marmot mid-rib , SW aspect 4000-4200′

 

12.13 Marmot crowns (lookers right of Lodge run) likely from 12-10/11 , West aspect 4300′. In this photo crowns can be seen in shaded areas below the ridge and on the side wall gully.

 

12.13 Debris and cornice chunks at the top of the Death gully on Marmot, likely from 12-10/11

 

12.13 Same picture as above showing runnout and debris from slab avalanche

 

12.13 Cross loaded slopes. Wind texture from the previous wind event is still visible under the recent new snow on Marmot WSW face

 

12.13 Small slab avalanches on the lodge roof

Avalanche Problem 1
  • Dry Loose
    Dry Loose
  • Aspect/Elevation
  • 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.

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

Cold temps overnight and through the day will keep DRY LOOSE a problem and on our radar for todays avalanche problem. Expect sluffs to be POSSIBLE to human trigger on steep slopes, greater than 40º, on all aspects, at all elevations. Any slopes previously affected by the 12/10-11 wind (above 3500 ft) OR affected by 11/23-24 rain (below 3500 ft) will have firm bed surfaces and be easier locations to trigger a sluff.

Small incremental storms brought approximately 10 to 12 inches of new snow to Hatcher Pass since last Saturday.  Strong winds followed, redistributing some of the new snow. Wind slabs that formed have become mostly unreactive and stubborn but can most definitely be felt underfoot while skiing and riding, especially on West to Southwest aspects at mid and upper elevation where winds gusted 30-39mph for 15 hours on 12/10-11.

12.13 Dry Loose avalanches (sluffs) on the ESE aspect of Skyscraper 3800′

Getting caught in a dry loose avalanche in steep terrain may sweep you into terrain traps compounding the overall hazard.  We mention this often because a significant amount of the terrain at Hatcher Pass involves navigating in, around, or above terrain traps.

We recommend avoiding terrain traps, skiing/riding one at a time, using appropriate safe zones, and using appropriate sluff management techniques.


Outlook for the next storm:

More precipitation is in the forecast for Friday.

Buried weak sugary facets and facet/crust layers are still buried and exist in specific locations, mostly below 3500 ft. These slabs will be unlikely to trigger today but not impossible.  Pay attention to this structure and where it exists in the snowpack. High end storm totals for Friday could potentially overload these weak layers.

Although HP only has approximately 3 ft of snow, cornices on leeward aspects have grown in size over the past week. Use caution and give cornices a wide berth when travelling in and around them.

Weather
Thu, December 14th, 2023

NWS AVG Forecast here.

NWS point forecast here.

Marmot Weather Station here.

Independence Mine Snotel here.

Frostbite Bottom Snotel here.

State Parks Snow Report and Motorized Access information here.

XC trail grooming report for Mat-Su, Anchorage, and Kenai here.

Observations
Recent Observations for Hatcher Pass