Haines Avalanche Center

Forecast Expired - 12/10/2021

Above 2,500ftHigh

1,500 to 2,500ftHigh

Below 1,500ftHigh

Degrees of Avalanche Danger

Low
Moderate
Considerable
High
Extreme

Avalanche Problems

Problem 1

Storm Snow:

Aspect: All aspects, especially wind loaded aspects and features N-NW-W.

Elevation: All Elevations – Widespread.

 

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. Recent accumulations of another 8″, gusty winds from the southeast, and warmer temperatures will increase the avalanche hazard significantly. Plenty of snow is available for wind transport! Natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended.

 

Look for signs of wind loading that include: cracking, collapsing, shooting cracks, hallow sounds, and strong over weak layering. Avoid wind loaded aspects and features.

 

Beware of  terrain traps (e.g. gully, rocks, dense timber, cliff, crevasse) or areas where snow could pile up quickly. Avoid traveling above or below terrain traps.

 

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

Aspect: All aspects and below terrain features.

Elevation: All Elevations.

 

Persistent avalanche problems are tricky. The question is: When will stress over-ride strength and cause a slab to fail?

  • Cold temperatures Dec. 3-5 created weak snow at the surface that is buried in many places under a strong wind slab in the upper snowpack.
  • Over a meter deep layering suggests old weak layers are buried and difficult to trigger but still reactive.
  • Toward the very bottom early season snowfalls and crusts linger and are still of concern.

 

It is possible that any surface avalanches could step down to the deeper weak layers, rain crust, or even the ground in alpine areas. 

 

  • One of the best ways to reduce your exposure to deeper 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

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. These slides were likely dated Dec. 1 when temperatures increased with strong winds from the South.

Weather

  • A low pressure system will move into the area with increased precipitation 6-8″, moderate southeast winds gusting strong and warming temperatures.
  • 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″  5″ / 0.35*  18″ / 1.15*  0′  Mod, SE  4″ / 0.30*
Flower Mountain @ treeline  50″ *  3″ / 0.15  8″ / 0.30  0′  Mod, E  2″ / 0.15*
Chilkat Pass @ 3,100ft  29″  2″ / 0.07  3″ / 0.15  0′  Mod, E  2″ / 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. Be prepared for an emergency and hypothermia. Winter is a high consequence environment. Carry bear spray.

Become a sustaining Haines Avalanche Center Member by clicking the poster or visiting dev.alaskasnow.org/joinHAC. Support local forecasts, observations, education and weather stations. Join a community of winter recreationalists. Benefit from collective knowledge and skills. Help keep your friends and family safe in the backcountry. Get a free limited edition mountain buff, or neck gaiter with a $50 membership (first 20 members!).

 

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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