Haines Avalanche Center

Forecast Expired - 12/23/2021

Above 2,500ftModerate

1,500 to 2,500ftModerate

Below 1,500ftModerate

Degrees of Avalanche Danger

Low
Moderate
Considerable
High
Extreme

Avalanche Problems

Problem 1

Persistent Slab:

Aspect: All aspects, most likely on wind loaded aspects and features SW-S-SE-E.

Elevation: All elevations, mainly at and above treeline.

 

NW winds are expected to increase this weekend. Watch out for new wind loading which could raise the danger level to considerable in some areas.

 

The Bottom Line:

While triggering an avalanche has become more difficult, strong over weak layering in the upper snowpack could still produce a slide. Remain vigilant around suspect terrain: exposed slopes greater than 30 degrees, below ridge-lines and in couloirs/gullies. If you venture into new terrain, keep in mind false positive confidence. Very cold temperatures continues to weaken snow at the surface and layers of concern deeper down.

 

Travel advice: Use safe travel techniques such as only exposing one person at a time both on the way up and down. Group up in safe zones that are out of harms way. Have good communication, including radios and a set plan in case of an emergency. Be practiced at companion rescue, identify potential hazards, and avoid possible trigger points on a given slope.

 

Identify old wind slab by looking for stiff or hollow surface snow, and looking for cracking, whumphing – treat these areas as highly suspect. You can find safer conditions in wind-protected areas with softer snow. Avoid terrain traps where snow could pile up quickly, or the consequences of a slide could cause injury or death.

 

The persistent slab danger is not healing, it is standing by waiting for the right trigger. Keep in mind that most avalanches are triggered by someone in the group.

 

  • Snowfall Dec. 6-10th alternated with wind events and was blown around by strong NW winds on Dec. 11th. A repeat of the same conditions occurred with NW winds Dec 19th, followed by 6″ of new snow, and now more NW winds.
  • Cold temperatures Dec. 3-5th created weak snow at the surface that is now buried in many places
  • Over a meter deep: old weak layers are buried and difficult to trigger, but still there.
  • Toward the very bottom: early season snowfalls and crusts linger and are very difficult to trigger but are still of concern for step-down potential.

 

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

 

 

Surface layers from Dec. 16th / Test pit results from Dec. 9th  / Full profile from Dec. 8th

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

This natural avalanche most likely occurred on Dec 11th on Mount Ripinsky’s back bowl during the recent wind event. It ran over a persistent weak layer on a NE aspect at 300ft, was 200ft wide and ran 800ft, with a average slope angle measured on Google Earth of 35 degrees.

Weather

Temperatures are starting to fall again, and we expect to remain in very cold, mostly clear conditions for the next several days. NW winds will increase as well, and wind chills could be brutal (-30 ish).

  • Moderate NW winds hit the slopes Dec 19-20th
  • Surface hoar formed on all aspects and elevations Dec 17-18th.
  • A strong NW wind event on Dec. 11-14, caused active wind loading
  • Early December has brought in about 2-4 feet of snowfall
  • November brought consistent heavy snowfalls, cold weather, and SE winds
  • October brought heavy snow in the alpine, followed by a few rain/sun crusts
 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 **   62″*  0″ / 0.0*  6″ / 0.60*  0′  light, NW  0″ / 0.0*
Flower Mountain @ treeline  45″  0″ / 0.00  3″ / 0.20*  0′  light, NW  0″ / 0.00*
Chilkat Pass @ 3,100ft  20″  0″ / 0.00  3″ / 0.19*  0′  light, NW  0″ / 0.00*

( *star means meteorological estimate )

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

Additional Information

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.

 

Education Video Links:

Announcements

Bottom Line: Weak layers are aging, not healing! Just because it is blue-bird, don’t discount your intuition! While triggering an avalanche has become more difficult, strong over weak layering in the upper snowpack could still produce a slide. Click the –Full Forecast– button below for more details. Please submit your observations!