Hatcher Pass Avalanche Center

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Sat, April 20th, 2024 - 7:00AM
Sun, April 21st, 2024 - 7:00AM
Allie Barker
Conditions Summary

Although the forecast season has finished, the avalanche season has not.  Please read below for some tips on NAVIGATING THE BACKCOUNTRY IN SPRINGTIME and AVALANCHE PROBLEMS ON THE HORIZON. 

Temperatures have risen significantly this week.  Expect the avalanche danger to be dynamic with the increase in daytime temperatures, multiple nights without a refreeze below 3500′ and sunshine in the forecast.  Expect to see wet avalanches this weekend.

Conditions will vary from frozen to breakable crust to corn and wet sloppy snow depending on aspect and elevation.  Choosing the right timing and aspect will make or break your backcountry adventure.

Soft turns have been found on true north aspects but I’d expect the whole compass (all aspects) to transition from moist to wet to an isothermal snowpack in the next few weeks.

Safe travel protocollocal weather stations, and recent observations will all be valuable resources for making safe decisions as avalanche conditions continue to change throughout the spring.

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This season HPAC has provided 54 forecasts, 73 professional observations, and 35 social media storm warnings, conditions summaries and 16 miles reports.  Thank you to all our sponsors and donors this season. Your contributions make our work possible and are a valuable community resource. We appreciate all of you.

We will continue to publish observations throughout the spring season. Submit them here.

Avalanche Problem 1
  • Normal Caution
    Normal Caution
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
More info at Avalanche.org

Navigating the backcountry in springtime can be challenging.

Although March felt like April and April now feels like March, we have finally seen a gradual increase and rise in temperature this week. The danger and likelihood of persistent slabs have started to dissipate.  On Wednesday 4/17 winds at 4500′ gusted SSE 21-38 mph on Marmot and 35-53 mph on Hatch for 12-15 hours and affected ski/riding quality more than contributing to an avalanche problem. Small winds slabs are expected to be stubborn to unreactive this weekend.

Expect wet avalanches to become more active as temperatures rise, combined with multiple nights without a good refreeze.  Temperatures have remained above freezing for the past 3 nights at 2700′, 2 nights at 3500′, and hovered at freezing at 4500′ last night.  Expect wet avalanche problems on southerly aspects before they become a problem on the entire compass.

Maintaining strict habits with safe travel protocol is a good habit during ‘green light’ conditions as well as red light. The main things are exposing only one person at a time, having escape routes planned, watching your partners closely, carrying and knowing how to use your rescue equipment.

Although Spring is here, 4+ ft of snow still exists at 3000′

Springtime Avalanche Concerns

Be alert for signs of danger and monitor trends.

1. Loose Wet Avalanches-Loose wet avalanches are typically the first avalanches we see as the snowpack warms up. They can be triggered by snow heating up especially near rocks and cliffs on steep slopes.  While they are relatively small and manageable on their own, they can be dangerous if they pick up enough volume, or if they push you into terrain traps. They can also trigger larger slab avalanches as they travel downhill. They are typically preceded by rollerballs or pinwheels rolling down slopes as they heat up. This is an easily avoidable avalanche problem. Expect wet loose sluffs to be possible on all aspects in steep terrain.

2. Wet Slabs–Forecasting for Wet slab avalanches  is very difficult.  Wet snow avalanches are caused by melt water which weaken the bonds (strength) of a buried weak layer, decreasing the strength of the snowpack which can lead to wet loose avalanches on the snow surface or larger wet slab avalanches that release either on weak layers within the snowpack or on the ground.  Wet slab avalanches can be highly destructive and require careful evaluation of the snow surface conditions to minimize your exposure. The best indication of wet slab avalanche potential is to monitor how deep you are sinking into the snow surface and pay attention to any smaller wet loose avalanches that are either human triggered or naturally occurring.  A common avalanche proverb says that three nights in a row of no refreeze is an omen of major wet slab avalanches.  It is best to avoid avalanche terrain and runout zones during these periods as the ingredients for large and destructive wet slab avalanches are all in place.

3. Cornices –Cornices are very large especially on the Marmot ridgeline above Rae Wallace in addition to many upper elevation leeward aspects.  Cornices can break off naturally, especially during warm weather when they start bending downhill. Simply avoid being underneath or near the tops of large cornices as they break farther back than expected. Cornices can trigger sluff and slab avalanches and are unpredictable this time of year.

4. Glide Avalanches– A separate but related avalanche problem is Glide avalanches.  When they happen is mostly unpredictable, however, where they happen is generally predictable because there is often a huge crack in the snowpack. Glide cracks are more likely during periods of active melting of the snowpack. Common places to find glide avalanches are places with rock slabs or a smooth ground surface which are common in much of the terrain at Hatcher Pass. Avoid spending time underneath as it could release at any time and create a large and destructive avalanche.

The bottom line for wet avalanches:
Get out early and get home early. Get off of–and out from underneath–any slope approaching 35 degrees or steeper when the snow becomes wet enough not to support your weight. Warning signs may include:
  • Rollerballs (pinwheels) in new snow that is getting wet for the first time
  • Natural or human triggered wet sluffs
  • Small sluffs fanning out into larger slides or running long distances
  • Cornices breaking off
  • Several days of strong melting combined with no refreeze at night.

These signs mean it’s time to head home or change to an aspect with cooler snow. Remember, even “smaller” slides can be dangerous in high-consequence terrain, such as above a terrain trap, trees, rocks, cliffs, or a long, large avalanche path. Plan your trip to have a safe exit out of the mountains.

Sat, April 20th, 2024


Independence Mine Snotel 3550′. Graphs courtesy of Keegan Krantz, Alaska NRCS Snow Survey

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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