Hatcher Pass Avalanche Center

Hatcher Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Sat, January 28th, 2023 - 7:00AM
Sun, January 29th, 2023 - 7:00AM
Jed Workman
Avalanche risk The Bottom Line

The avalanche danger is MODERATE above 2500′ today and LOW below that.

After a month of stale conditions, we finally received snow, wind, and a new avalanche concern.

Two significant human-triggered avalanches yesterday make it clear that human-triggered avalanches are possible. Today will be no different.

An additional hazard today is the human factor. We have all been starved for snow, however, the new snow comes with caution, so get your game face on!

Soft persistent slab avalanches up to 18″ deep will be possible to human trigger at mid to upper elevations on all aspects on slopes 30 degrees and steeper.

It will be possible for subsequent people to trigger an avalanche on the same slope. Tracks are not an indicator of stability for this avalanche problem.

Review the observations, read the entire forecast, and familiarize yourself with today’s avalanche problem before you head into the backcountry. Let’s have a fun, but safe weekend in the snow.

Special Announcements

Tickets are on sale now for the Annual HPAC Cabin Fever Reliever Fundraiser highlighting HOPE SOCIAL CLUB! on Feb 4th here. Tickets will sell out! Come celebrate 15 years of avalanche forecasting with us! The location has changed to the Palmer Senior Center, 1132 South Chugach Street, Palmer, AK 99645

Sat, January 28th, 2023
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
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

Three avalanches were reported recently.

One was triggered yesterday by a snowmachine at the top of the archangel trail by the old Lane hut location with no involvement, one was triggered by a skier near Friendship Pass which included a partial burial but no injuries, and one was natural which likely occurred during the 1/23-24 storm in the Rock Garden/Pinnacle Valley.

Same avalanche as pictured below

1/27 – Lane Hut area, WSW, ∼4300′, Snowmachine trigger point marked by red arrow, likely failed below 1/23 storm snow, about 18″ deep, D1.5

1/27 – Skier triggered soft slab avalanche near Friendship Pass, SW, 4800′, Partial Burial, D1.5


1/23-24 – Pinnacle Shoulder, West, 4800′ natural slab avalanches which likely occurred during the 1/23-24 storm, failing at old snow/new snow interface, D2


Conditions Photos

This picture shows the nature of the recent January warm storm’s ability to glue snow to very steep rock faces. It is rare for these peaks to not be showing rock.

High peaks up the Archangel Valley

While we are well into the winter and headed into the Spring snow season in Alaska, we still don’t have that much of a base. At least three snowmachines were damaged yesterday due to impact with buried rocks. Smasher’s Pass needs more snow for snow machining, but for skiers, boarders, and snowshoer’s it is uncommon to be hitting rocks on most slopes above 2500′.

Avalanche Problem 1
  • Persistent Slabs
    Persistent Slabs
  • Certain
    Very Likely
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
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

It’s now been 7 days since the 1/23 storm which dropped 1.4″ of water in about 8″ of snow and 3 days since the 1/25 storm which dropped 0.4″ of water in about 2-3″ of snow at 3550′. These back-to-back storms brought about 10-11″ of warm dense snow which has bonded fairly well to the old December widespread wind-packed firm surface. Winds associated with these storms drifted the new snow onto West to North aspects and terrain features, up to approximately 18″ deep.

The December wind-packed snow is highly variable in thickness, to non-existent. Additionally, the 1/23-26 new snow was wind scoured and drifted. This makes for a complicated weak layer problem that varies in continuity across aspects, slopes, and terrain features.

There are specific locations where triggering an avalanche is still possible. Picking out exact problem locations will be difficult. 

Expect the new snow to fail above the old December wind packed firm snow on a thin layer of rounded facets, or just below that in a layer of faceted sugar snow. Yesterday’s avalanches appear to have failed at the 1/23 interface of newer snow over the December wind-packed snow. The video below shows exactly this situation.

Our instability tests have shown some variability and some have shown propagation. Both our data and recent avalanches are consistent and confirm that small to large human-triggered soft slab avalanches are possible in specific locations up to 18″ deep.

Numerous people were in the backcountry yesterday, recreating on steep slopes, and did not trigger avalanches while a few did. This information is useful and somewhat representative of stability but needs to be taken with a grain of salt.

It’s important to note that we have not been experiencing whumping and cracking, and people who have triggered avalanches also did not experience this warning sign prior to triggering avalanches.

In order to increase your safety, employ rigorous travel protocol and be prepared for companion rescue.

Below is a snowpit on the SW aspect of Marmot that demonstrates the snowpack has strong strength, but once that strength is exceeded propagation is present in failure and avalanches are possible. There may be weak points in the snowpack due to spatial variability we can’t readily see, and it may be the 2nd, 3rd, 4th, etc person who finds the trigger point and triggers an avalanche. Tracks on a slope are not a sign of stability with this avalanche problem.  Take the snowmachine triggered avalanche near the old Lane hut location for example, it was the second rider on that slope who triggered the avalanche. See pictures above in recent avalanches.


Sat, January 28th, 2023

Overnight IM Snotel did not show any measurable precipitation. Frostbite Bottom Snotel reports 0.1″ SWE, however, the Skeetawk snowboard inn close proximity to the Frostbite Snotel showed nothing.

The next best chance for snow after this morning’s possible trace is Sunday for up to 1″.

Avalanche Weather Guidance

National Weather Service Anchorage AK

339 AM AKST Sat Jan 28 2023 .

DISCUSSION…A strong upper level ridge will remain over Southcentral and the Gulf of Alaska through Sunday, then weaken and begin to shift a bit to the east Sunday night through Monday. Warm air moving up and over the ridge has started to move into Southcentral. A near continuous very gradual warming of temperatures aloft will continue through tonight, especially along the Kenai and western Chugach Mountains. Some spotty light precipitation is possible today, with rain, snow, and freezing rain all possible, depending on location. In most cases it will not be measurable precipitation. The one exception is the western side of the Talkeetna Mountains (including Hatcher Pass) where some very light snow accumulation is possible. A series of weak upper level short-waves riding up the west side of the ridge will arrive in Southcentral Sunday afternoon through Sunday night, bringing widespread light precipitation. Temperatures will cool and snow levels will begin to fall as the atmosphere becomes saturated. Generally expect snow levels to settle somewhere in the 800 to 1500 ft range. Freezing rain will also remain a threat into Monday for lower elevations.

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.

Recent Observations for Hatcher Pass