Hatcher Pass Avalanche Center

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ARCHIVED - Forecasts expire after 24 hours.
Issued
Thu, February 1st, 2024 - 7:00AM
Expires
Fri, February 2nd, 2024 - 7:00AM
Forecaster
Ryan Lewthwaite
Avalanche risk The Bottom Line

The avalanche danger is MODERATE at the mid and upper elevations and LOW below 2500 feet. It will be possible to trigger dry loose avalanches within the recent snow on terrain steeper than 40°. Natural avalanches are unlikely to occur. With continued arctic air temperatures expect this avalanche problem to remain active for the next few days.

Special Announcements

The HPAC Cabin Fever Reliever with The Jangle Bees and the drawing for our winter raffle are coming up next weekend, 2/10! Get your tickets to the party and raffle tickets today! All proceeds support HPAC and sustainable avalanche forecasting in Hatcher Pass.

RESCHEDULED for Feb 3rd! Anchorage (Glen Alps): The Avalanche Rescue Skills Workshop will be this Saturday. The event is hosted by the Anchorage Nordic Ski Patrol and Friends of Chugach Avy. Come anytime between 10:30am and 3:30pm to practice with your rescue gear. Several stations will be set up and folks available to assist and ask questions. Cross your fingers the weather isn’t too cold this time.

Thu, February 1st, 2024
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
Fri, February 2nd, 2024
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
Fri, February 2nd, 2024
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

~Several parties on Wednesday 1/31 were able to trigger sluffs in steep terrain. One individual on Microdot triggered a large loose dry avalanche on a south aspect at 4500 feet in elevation that ran about 300 feet.

~Natural loose dry avalanches were observed on numerous different aspects in terrain steeper than 40° that were small to large in size (D1 to D2).

Human Triggered Loose Dry Avalanches on Microdot South aspect at 4500 ft 1/31/24

Human Triggered Loose Dry Avalanches on Microdot South aspect at 4500 feet 1/31/24 (Kosachuk’s photo)

Natural Loose Dry Avalanches on Marmot Southwest Aspect at 4300 feet 1/31/24

Natural Loose Dry Avalanches on Marmot Southwest Aspect at 4300 feet 1/31/24

Natural Loose Dry Avalanches on Arkose Ridge West Aspect at 4000 feet 1/31/24

Natural Loose Dry Avalanches on Arkose Ridge West Aspect at 4000 feet 1/31/24

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

A relatively efficient and chilly storm refreshed the slopes of Hatcher Pass with 6 to 8 inches of low density snow on January 28th & 29th. The cold ambient air temperature and initial lack of wind resulted in an evenly distributed layer of unconsolidated new snow. During the day on January 29th light to moderate winds began to transport the new snow. Luckily the duration was short-lived and only a minor surface wind skin formed on leeward aspects facing southwest through northeast. This wind affected snow is 1 to 2 inches thick and slabs are small and disconnected. It is unlikely that this thin surface layer will propagate failures resulting in a large avalanche. 

As the skies cleared and people began pushing into steeper terrain, some natural and human triggered loose dry avalanches (D1 to D2) were visible. Most of the avalanches are small and easy to avoid but a few are a bit larger in size and entrained much of the 6-8 inches of new snow. Debris and evidence of this avalanche problem can be found on all aspects at the mid and upper elevations. Some point releases originated from rocky outcrops, convexities, and in locations where previously firm surfaces exist. Terrain traps and gullies are places where it is possible to trigger a dry loose avalanche and a likely place someone could get caught and buried. 

Prior to the storm a 15 day dry spell, with some cold and clear conditions allowed the snowpack to facet-out older stiffer layers. The result was a mostly stable snowpack with areas of firm surface snow near windswept ridgelines. Currently slopes steeper than 40° are the most susceptible to triggering small to large loose dry avalanches. Many of these sluffs are slow moving but can entrain enough snow to bury or injure a person, especially on southern aspects where firm bed surfaces are present. We recommend avoiding terrain traps, riding one at a time, using appropriate safe zones, and sluff management techniques. As the clear and cold conditions persist expect surface snow to remain reactive and the dry loose avalanche problem to continue.

Natural Loose Dry Avalanches on Marmot Southwest Aspect at 4300 feet 1/31/24

Natural Loose Dry Avalanches on Marmot Southwest Aspect at 4300 feet 1/31/24

Weather
Thu, February 1st, 2024
Very cold air temperatures 2/1/24

Very cold air temperatures 2/1/24

A rapid 19F degree drop in 2 hours at Marmot weather station on 1/29/24

A rapid 19F°  drop in 2 hours at Marmot weather station on 1/29/24

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