Hatcher Pass Avalanche Center
Hatcher Pass

Hatcher Pass RSS

Archives
ARCHIVED - Forecasts expire after 24 hours.
Issued
Tue, January 24th, 2023 - 7:00AM
Expires
Wed, January 25th, 2023 - 7:00AM
Forecaster
Jake Kayes
Avalanche risk The Bottom Line

Heads up conditions have changed! 

7 inches of dense snow has fallen in Hatcher Pass in the last 24 hours.

The avalanche danger is CONSIDERABLE above 3500 feet on all aspects. Below 3500 feet the avalanche danger is MODERATE on all aspects.

Human triggered storm slabs 6-8” thick are likely on all aspects at upper elevations. Storm slabs will be small to large in size.

Human triggered wind slabs are likely at upper elevation on Northwest thru North aspects. Wind slabs will be small in size, natural avalanches are possible with additional wind.

More snow is in the forecast for Wednesday which may increase avalanche hazard again.

Tue, January 24th, 2023
Upper Elevation
Above 3,500'
3 - Considerable
Avalanche risk
Mid Elevation
2,500'-3,500'
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.
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

Around 7 inches of new snow with 1.4 inches of snow water equivalent has fallen in the last 24 hours. This new snow is very dense.

Human triggered storm slabs 6-8” thick are likely at upper elevations on all aspects. These avalanches will be small to large in size.

The mid and low elevation bands received around 6” of snow new snow but is much lower in density. 

Cracking and collapsing will be red flags for this avalanche problem. 

If you do choose to head out into avalanche terrain we recommend being cautious and gathering information about the snowpack as you travel.

Avalanche Problem 2
  • Wind Slabs
    Wind Slabs
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

Last night winds from the Southeast lasted for 14 hours with gusts up to 30 mph. These winds have created thin wind slabs on Northwest and North aspects at upper elevations. Human triggered wind slabs are likely. Natural avalanche are possible with additional wind.

Winds are forecasted to continue throughout the day and should taper this afternoon. 

 

Weather
Tue, January 24th, 2023

7″ of snow has fallen with 1.4″ SWE at IM Snotel (3550′) in the last 24 hours.

The next chance for snow is Wednesday with a chance for 10″ of snow.

Avalanche Weather Guidance

National Weather Service

Anchorage AK 329 AM AKST Tue Jan 24 2023

.DISCUSSION… A front lifts northward from the Gulf of Alaska and inland of the north Gulf coast through this afternoon. Although there will be upslope enhanced precipitation for the mountainous areas near Cordova, the bulk of precipitation will be for the mountainous areas of east Turnagain Arm near Whittier and western Prince William Sound. As warmer air comes northward with the front, snow levels look to climb generally to 1000-1800 feet with the highest for the Chugach near Cordova and the lower levels for eastern Turnagain Arm. After the front passes in the afternoon, upslope enhanced precipitation will continue through the evening and overnight hours tonight. A larger storm system arrives for early Wednesday morning with precipitation generally lasting into the early evening hours before tapering off Wednesday afternoon to evening. There is still some uncertainty with the ultimate track that the low will take; however, based on the track of the upper level short-wave the heaviest precipitation will fall across Chugach of eastern Prince William Sound (surrounding Cordova/Valdez). Gusty southeasterly winds around 35-55 mph will also accompany this low as it moves inland for the northern Gulf coast mountains near Cordova and the Copper River Delta.

NWS AVG Forecast here.

NWS point forecast here.

Marmot Weather Station here.

Independence Mine 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