Hatcher Pass Avalanche Center

Hatcher Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Sat, February 25th, 2023 - 7:00AM
Sun, February 26th, 2023 - 7:00AM
Allie Barker
Avalanche risk The Bottom Line

The avalanche danger is MODERATE for PERSISTENT SLABS 4 to 12″ thick on all aspects, at all elevations, on slopes 35º and steeper.

This weeks storm brought a new thick coat of paint to Hatcher Pass but heads up, looks can be deceiving! Expect stiff snow and slab like conditions. Last week’s low density powder fest is old news but don’t fret, cold temps in the forecast will improve conditions in the coming days.

Be aware of the human factor that will accompany sunshine this weekend. We recommend a conservative approach to decision making in the backcountry this weekend after a big shift from several weeks of normal caution and good stability.

Sat, February 25th, 2023
Upper Elevation
Above 3,500'
2 - Moderate
Avalanche risk
Mid Elevation
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

On Friday we observed a couple large Natural avalanches from mid to end of the storm on 2.23. We also observed several small to large natural loose dry avalanches (sluffs).

We believe that numerous other avalanches occurred on 2.23 but they were challenging to identify due to the new 23-25% density snow.

2.23 Arkose ridge above Goldmint and behind the Punkspines. Large natural avalanche 4400′ WSW aspect. Scroll in to see the crown.


2.23 Arkose Ridge, large natural slab 3800′ W aspect. Scroll in to see the crown just below the ridge.


2.24 Natural, Marmot gully 3500′ SE aspect




Recent Conditions

Conditions have changed over the past few days. Photos below show smooth wind slabs and the effect winds have had on snow surfaces this week.

2.24 East face of Eldorado

2.24 SSW Marmot

2.24 SSE aspect of Skyscraper


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 will be possible to human trigger Persistent Slabs, 4 to 12″ thick, on all aspects, at all elevations, on slopes steeper than 35º. Natural avalanches are unlikely.

The February 22-24th storm brought less snow than anticipated, however, we did receive a shocking 2″ SWE (water) with 8″ new snow @IM 3550′ and 1.7″ SWE with 7″ new snow @Frostbite 2700. It’s hard to believe we live in a continental snow climate because this storm resembled what regularly occurs in a maritime zone.

In addition to moist snow, winds gusted SSE 17-25 mph for 12 hours on 2/23.  Fortunately, dense snow takes stronger wind to build wind slabs which limited the size of the wind slabs.

We have not mentioned persistent slab as a problem in the forecast since January 28th, almost a month, which might be a record. It’s important to distinguish a persistent slab problem from other avalanche problems. Persistent slabs tend to hang out and persist in the snowpack longer compared to storm slabs and wind slabs which are short lived problems.

It will be helpful to dig in the snowpack, do pole tests, and instability tests to determine most likely locations for triggering a slab.  Most likely locations will be where persistent slabs are sitting on near surface facets (NSF) on smooth bed surfaces like buried wind slabs, rain and sun crusts, have a shallower snowpack and/or slopes that have previously avalanched this season. The NSF layer formed during the cold weather Feb 19-21.

This video below shows an ECT with propagation failing on NSF and graupel on Friday on the south ridge of Marmot. We also experienced whumping/collapses in the snowpack on this layer prior to turning around.

The profile below shows the structure of this weeks new dense snow.  On Friday we got propagation approximately 12″ deep that failed on NSF and graupel. We expect the buried NSF to be widespread, however, locations where the facets are sitting on old, smooth, crusts are more concerning and will be more likely locations to trigger an avalanche.

Pole/probe tests and formal stability tests will help you identify this problem. Whumping and shooting cracks will be red flags for this avalanche problem.

If you head into avalanche terrain today, utilize strict safety travel protocols, travel one at a time from safe zone to safe zone, only have one person on slope at a time, ensure all members of your party are carrying and know how to use beacons, shovels and probes, and avoid slopes with terrain traps.

Sat, February 25th, 2023

2.22-2.24 Hatcher Pass received approximately 1.9″ SWE with 8′ new snow @IM and                    1.7″ SWE with 7″ new snow @Frostbite. Winds gusted SSE 17-23 for 12 hours on 2/23.

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