Hatcher Pass Avalanche Center

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ARCHIVED - Forecasts expire after 24 hours.
Fri, November 17th, 2023 - 7:00AM
Sat, November 18th, 2023 - 7:00AM
HPAC Staff
Avalanche risk The Bottom Line

The avalanche hazard remains HIGH today in the mid and upper elevations due to an unusual early winter storm. We do not recommend traveling in avalanche terrain today. The hazard remains Moderate at low elevations.

If you are tempted to travel in the low elevations, remember that avalanches from above in the mid-elevation band may be able to run down into the lower elevation band. Use extra caution to avoid this possibility.

New snow overnight has significantly overloaded a weak snowpack. Natural avalanches are likely and human-triggered avalanches are very likely at the mid to upper elevations on all aspects. It will be possible to remotely trigger avalanches above you, from the flats, or on adjacent terrain, making this hazard dangerous and difficult to predict.

Over the last 24 hours Hatcher Pass has received 10-12″ of new snow. Storm total since Wednesday has reached 22″. The Marmot snow stake is showing 3 feet of settled snowpack for the season, and the height of snow at Independence Mine Snotel is reporting 43″ this morning.

The storm will be tapering off today and visibility may improve. The temptation to get out into the snow is strong, but we will be avoiding the backcountry today and allowing the snowpack time to adjust to this new load.

More details and information will become available as soon as the weather and snowpack allow us to safely enter the field again.

Fri, November 17th, 2023
Upper Elevation
Above 3,500'
4 - High
Avalanche risk
Mid Elevation
4 - High
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.
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

A widespread poor snowpack structure with a persistent slab problem and weak basal October facets (sugar snow) are the primary concern. This layer has already failed in previous storm cycles, and will again in the current storm cycle. Avalanches on this layer may take out the whole snowpack, sliding at or near the ground level.

Storm snow avalanches will also be a problem today on all aspects. These will be deeper and more dangerous at the mid to upper elevations with the added possibility of stepping down to the basal facets at the ground. At the lower elevations, these will be shallower, and possible to human trigger.

Dry Loose avalanches are another concern on all aspects at all elevations on slopes 40 degrees and steeper. With significant amounts of dry new snow, you can expect dry loose “sluffs” to be abundant and sizeable.


Fri, November 17th, 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.

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