Haines Avalanche Center

Forecast Expired - 12/26/2021

Above 2,500ftConsiderable

1,500 to 2,500ftModerate

Below 1,500ftModerate

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:

Aspect: Most likely on wind loaded aspects and features SW-S-SE-E.

Elevation: Mainly above treeline.

 

 

The Bottom Line:  NW winds increased this weekend. Watch out for new wind loading and avoid freshly loaded slopes. Look for signs of sensitive surface slab conditions including natural avalanche activity, shooting cracks and whumphing or collapsing. In specific areas wind slab could be layered over surface hoar and old weak surface snow – that is prime for human triggering.

 

 

 

Travel advice: Avoid wind loaded aspects at and above treeline. Look for visual clues such as active wind loading and blowing snow. Stay away from slopes below ridgelines, roll-overs, or cross loaded gullies and other features steep enough to slide >30 degrees. Beware of fresh cornices that have formed from the wind and are brittle due to decreasing temperatures. Avoid terrain traps where snow could pile up quickly, or the consequences of a slide could cause injury or death.

 

Note: Surface avalanches could step down to weaker buried layers, see Persistent Slab problem.

 

 

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

Elevation: All elevations, mainly at and above treeline.

 

 

The Bottom Line: While triggering an avalanche deeper in the snowpack has become more difficult, strong over weak layering in the upper snowpack could still produce a slide. Remain vigilant around suspect terrain and potential trigger points on 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. Identify and avoid thin areas where weak layers are more likely to trigger a slide from. 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.

 

You can find safer conditions in wind-protected areas with softer snow. The persistent slab danger is not going away, it is standing by waiting for the right trigger. We have not had a crush and flush cycle, or stabilizing event. 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. 

 

***We should also should pay close attention to what is happening on the surface, keep an eye out for surface hoar and weak sugary snow. Extended cold, clear conditions in areas with light winds and higher humidity is not a good recipe for stable snow from the next storm.  Stay tuned….***

 

Test pit from Dec. 23rd with buried crust 70cm down

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 3,000ft, was 200ft wide and ran 800ft, with a average slope angle measured on Google Earth of 35 degrees.

Weather

Saturday’s cold temps and strong northwest winds were enough to transport snow and wind load leeward areas. Expect to see slightly warmer temperatures today before a few inches of snow on Monday. Then back to very cold temperatures mid week.

 

  • Surface hoar formed on all aspects and elevations Dec 17-18th.
  • Moderate NW winds hit the slopes Dec 19-20th
  • 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 **   61″*  0″ / 0.0*  0″ / 0.00*  0′  mod, N  2″ / 0.05*
Flower Mountain @ treeline  43″  0″ / 0.00  0″ / 0.00*  0′  mod, N  0″ / 0.00*
Chilkat Pass @ 3,100ft  19″  0″ / 0.00  1″ / 0.04*  0′  mod, N  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.


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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.

 

Education Video Links:

Announcements

Bottom Line:  NW winds over the last couple days were strong enough to transport large quantities of snow in the alpine. Watch out for wind loaded areas! Remain vigilant around suspect terrain and potential trigger points on exposed slopes greater than 30 degrees, below ridge-lines and in couloirs/gullies! Identify and avoid thin areas where weak layers are more likely to trigger a slide. Click the –Full Forecast– button below for more details. Please submit your observations!