Haines Avalanche Center

Forecast Expired - 12/09/2021

Above 2,500ftConsiderable

1,500 to 2,500ftConsiderable

Below 1,500ftConsiderable

Degrees of Avalanche Danger

Low
Moderate
Considerable
High
Extreme

Avalanche Problems

Problem 1

Persistent Slab:

Aspect: All aspects and below terrain features

Elevation: Mainly Treeline and above

 

Observations from Ripinsky yesterday found collapsing and cracking on old wind slabs in the midpack. These slabs were failing on softer layers (facets) 1-3ft deep, that formed over the last two weeks. Snowpit results found clean, active shears 1 meter deep, which means potential for propagation and a lack of friction on the layer.

 

As if that isn’t enough to give you pause, we have also found significant weak facets at the bottom of the alpine snowpack in both zones, and the lingering October Rain Crust with weak layers above and below it. It is possible that any surface avalanches could step down to the deeper rain crust, or even the ground in alpine areas. 

 

  • One of the best ways to reduce your exposure to deep persistent weak layers would be to stick to areas of deeper snowpack (>1m deep). But be wary of hidden rocks that can act as trigger points, and thin areas around the margins of a slab.
  • Look and listen for deep whumping! Report any natural avalanche activity on these deeper layers!

 

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Loose Snow:

We received  20″ of new snow in this zone over the last few days. This new snow came in cold, dry, and loose, with little wind. The result is lots of sluffing in steep terrain. Even steep tree runs have been causing significant sluff.

 

Step down potential: large sluffs create a lot of force on the snowpack and can easily trigger deeper, more stubborn weak layers. Step down avalanches are likely given our persistent weak layer problem (above).

 

Otherwise, loose dry avalanches are usually relatively harmless to people. They can be hazardous if you are caught and carried into or over a terrain trap (e.g. gully, rocks, dense timber, cliff, crevasse) or down a long slope. Avoid traveling in or above terrain traps

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

Reports from the last week: A large natural avalanche was reported on a west aspect near 3920 in the Lutak Zone (See Persistent Slab problem). We also had reports of natural avalanches above Chilkoot Lake.

Weather

We’ve had about 20″ of low-density new snow this week in the Lutak zone, and around 8″ in the Transitional zone.

Last week, it snowed 6-14″. Winds switched from SE to NW and increased into typical northerly outflow as temperature plummeted into the single digits.

October brought heavy snow in the alpine, followed by a few rain/sun crusts, followed by regular heavy snowfalls in November.

 Snow Depth [in] Last 24-hr Snow/SWE [in] Last 3-days Snow/SWE [in]  Today’s Freezing Level [ft]  Today’s Winds Next 24-hr Snow/SWE
Mount Ripinsky @ treeline **   67″  8″ / 0.50*  18″ / 1.15*  0′  Light, NW  7″ / 0.40*
Flower Mountain @ treeline  50″ *  2″ / 0.10  8″ / 0.30  0′  Light, NW  5″ / 0.30*
Chilkat Pass @ 3,100ft  29″  0″ / 0.00  3″ / 0.15  0′  Light, NW  3″ / 0.20*

( *star means meteorological estimate )

** The Ripinsky weather station is in need of repair, and will likely be down until Summer.

Additional Information

Beware of deep treewells which can trap a person. It’s deep out there. Temperatures and wind chill are cold. Be prepared to prevent hypothermia.

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Practice like you play. Make sure all your rescue gear is fully functional and your beacon has NEW batteries. Make sure 1) everyone in the group has a functioning beacon, shovel and probe 2) knows how to use them and 3) has trained in companion rescue in the last year. Keep your skills fresh. If you head into the hills, watch out for red flag avalanche conditions, natural avalanches, whoomphing or collapsing, and shooting cracks.

 

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