Hatcher Pass Avalanche Center
Hatcher Pass

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ARCHIVED - Forecasts expire after 24 hours.
Issued
Thu, January 26th, 2023 - 7:00AM
Expires
Fri, January 27th, 2023 - 7:00AM
Forecaster
Jake Kayes
Avalanche risk The Bottom Line

It’s been a week of change at Hatcher Pass with two warm weather systems affecting the forecast area.

Above 2500 feet the avalanche danger is Moderate. Below 2500 feet the avalanche danger is Low.

At mid and upper elevations small to large human triggered storm slabs are possible and natural avalanches are unlikely. 

The NWS expects the storm to end sometime this afternoon. Southwest winds with sustained speeds of 25 mph and 30 mph gusts are expected today. An additional 4 inches of snow is expected. 

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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!

Thu, January 26th, 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'
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

Visibility limited our ability to get more detailed observations of the area, however, we noticed some patterns with the avalanches we observed.

On Jan 24th forecasters observed multiple natural avalanches on north aspects near ridgelines and on cross-loaded features. These avalanches occurred above 3400’ where winds were the strongest.  We believe that wind loading contributed to these avalanches. 

Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
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

After almost of month of drought, the pattern finally changed with the 1/23 storm.

Over the last 72 hours, there have been two significant warm weather events in Hatcher Pass. Click the weather tab for more info. These storms have brought relatively warm temperatures and new snow with some spells of light rain at all elevations. 

Snow and winds deposited snow on 1/23-24 and built slabs 1-2 feet thick on Northerly aspects and leeward features. These slabs failed at the new snow/old snow interface, where a crust formed during the warm storm. See Recent Avalanches.

Today’s new snow and winds will again transport snow and continue to build soft slabs that have the potential to fail at the new snow old snow interface, approximately 4- 6 inches deep. Additionally, the added weight may result in any avalanche being triggered to step down to the 1/23 layer producing larger and deeper avalanches up to 2 feet deep.

Small to large human-triggered storm slab avalanches are possible on all aspects. Natural avalanches are unlikely. These avalanches will be located at mid and upper elevations on slopes steeper than 35 degrees. 

With warm temperatures in the forecast, we expect stability to increase over the next 24 hours. 

1/24 Significant wind transport on 4068′

Hand pits and pole probes will help you identify this problem shooting cracks and collapsing will be red flags for this avalanche problem. 

Visibility may be limited today and it may be difficult to identify avalanche terrain. 

 

Weather
Thu, January 26th, 2023

Frostbite Bottom 2700′ Snow Totals

1/23-24: .9″ of SWE and 6″ of new snow

1/25-26: .4″ of SWE and 2″ of new snow

Frostbite Bottom Jan 23-26th temp and wind speed

Date
AKST
Temp
F
Spd
mph
Gust
mph
Dir
deg
Min 27 0 0 N
Max 38 16.6 38.5 N
Avg 32.2 4.1 10.6 SW

Independence Mine 3550′ Snow Totals

1/23-24: 1.5″ of SWE and 8″ of new snow

1/25-26: .4″ of SWE and 3″ of new snow

Independence Mine Jan 23-26th temps and wind speed

Date
AKST
Temp
F
Spd
mph
Gust
mph
Dir
deg
Min 24 0 0 N
Max 35 14.1 27.7 NNW
Avg 27.6 5.3 11.4 SSE

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
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