Haines Avalanche Center

Forecast Expired - 01/08/2023

Above 2,500ftModerate

1,500 to 2,500ftModerate

Below 1,500ftModerate

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Persistent Slab:

The Bottom Line: We have a new weak layer to worry about, buried surface hoar (about 2ft deep). In addition, we have three lingering facet layers about 3-5ft deep, and at the ground (See Deep Slab problem below). These layers are all adjusting to a heavy new load of snow that wasn’t enough to break the weak layers, which means there is still a lot of stress being stored in the snowpack. Don’t be the trigger that unleashes this stored energy. Avoid thin rocky areas which could be trigger points, never expose more than one person at a time to slopes 30-degrees and steeper, and don’t enter avalanche terrain without a plan for how to manage an avalanche that could break far wider and larger than you expect. Give yourself an extra margin of safety.

 

Surface Hoar Layer Beneath the New Snow:

  • On Dec 31 we observed a widespread surface hoar layer in the Pass. This was likely also present in the Transitional Zone. It was quickly buried by at least 2ft of new snow.
  • Observations 1/5 found one area of widespread natural avalanches in a wind protected pocket in the Takhin ridge, likely failing on this surface hoar layer.
  • Buried SH layers are tricky — they’re hard to find, and may only exist in wind-protected areas. But anywhere they are present you should be highly suspicious of that slope.
  • It would be best to avoid wind-protected pockets that may be harboring this dangerous weak layer. Make continual assessments on test slopes and with stability tests.

 

Photo of buried surface hoar 1/6 at Haines Pass near treeline at 2,500′ on S-aspect with ECTP 23 & 24 down 60cm that showed propagation potential.

 

Weak faceted snow 3ft deep:

  • Weak facets exist down ~3ft from the December 16-26th cold snap
  • Identify surface slabs over weak old snow by probing, digging pits, looking for shooting cracks and listening for collapses, or whumps.
  • Practice safe travel technique and avoid suspect pockets of slab. Surface avalanches could step down to deeper weak layers.

 

Photo of weak faceted old snow under the surface slab now buried under two more feet of snow 12/29 at Haines Pass near tree-line at 2,500′ on S-aspect.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Deep Slab:

Ever hear of “Deadly Moderate” conditions? We are in a situation where triggering a deep slab avalanche is somewhat unlikely, but the consequences would be very high. Expect this danger to be here for a while. There isn’t much we can do to avoid it if we enter avalanche terrain. We should remain aware that very deep and wide destructive avalanches need to be considered and planned for accordingly. Pay attention to run-out paths and where safe zones are considering large to very large avalanches.

 

The following old facet layers remain a concern above 1000ft, and any smaller avalanches in the upper snowpack could step down, leading to a massive avalanche.

 

Old Melt Layers and Crusts:

  • A buried persistent weak layer about 130cm deep (The “Big Warmup” Layer, Formed Nov 17th) is still a concern.
  • It is a thick refrozen crust with weak faceted snow above. This is an unusual and unpredictable weak layer because it formed during a thaw event and then re-froze while cold temperatures faceted the stout crystals.
  • A wide safety margin is necessary. This setup could produce avalanches that break wider than expected, and are most likely to be triggered from shallow trigger points like rocks or small trees. You could ride the same slope numerous times until that right spot produces a large destructive slide.

 

Observations in all zones throughout December found moderate strength and quick propagation on failures within the “Big Warmup” layer. We know it to exist at all elevations above 1000ft — even up to the highest summits. We expect this layer (and other midpack crust-facet layers) to be an ongoing issue going forward.

 

Depth Hoar at the Ground (Above 3,000′):

  • October snow followed by long cold snaps created depth hoar at the ground in most areas. These angular snow grains are well developed into a weak layer that behaves like brittle glass.
  • As the snow gets deeper, the load over this layer increases, and it could collapse. You are most likely to human-trigger this layer from shallow spots around rocks, or trees, or have a surface avalanche step down to the ground on this layer. Any slides that break to the ground are likely to be deadly.

 

Photo showing the “Big Warmup” facet layer in the Transitional Zone at 2500ft, on Jan. 2. Test result was ECTP18 on this layer that demonstrated propagation potential.

 

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

This week we observed one area on the Takhin ridge (E aspect around 3000ft) with several D2-D3 natural avalanches that ran about 2ft deep with very wide and complete propagation. This was in a protected basin where Surface Hoar likely grew before the last storm. We also observed widespread natural dry-loose slides in the usual steep areas.

Weather

Forecast:

Light snowfall (1-4″) is expected Friday as a weak front moves through our area. NW winds should be moderate. There might be another inch or two of snowfall on Saturday before things clear out for Sunday. Temperatures will be remaining mostly steady through the weekend, 20-30F.

 

Recent Weather Summary:

  • A strong front brought 24-30″ of snow above 2000ft on Jan 2nd.
  • There was widespread Surface Hoar growth on Dec 31st.
  • Dec 23-26 brought 10-18″ of new snow and a sharp rise in temperatures from -10F to 30F along with variable winds
  • Dec 16-23 brought strong NW winds and arctic cold temperatures
  • Dec 15 brought warmth/light rain up to 2600ft
  • There was a strong and cold NW wind event Dec 9 and 10
  • Complete Season Histories:     Transitional Zone     Lutak Zone
 Snow Depth Last 24-hr Snow/SWE Last 3-days Snow/SWE  Today’s Freezing Level   Today’s Winds Next 24-hr Snow/SWE
Mount Ripinsky @ 2,500′  79″  1″ / 0.05″  3″ / 0.20″  100′ light, NW   3″ / 0.20″*
Flower Mountain @ 2,500′  55″  0″ / 0.00″  3″ / 0.15″  0′ light, NW   1″ / 0.10″*
Chilkat Pass @ 3,100ft  32″   0″ / 0.00″  3″ / 0.15″  0′ light, NW   1″ / 0.10″*

( *star means meteorological estimate )

Additional Information

Be careful of rocks and hidden hazards like crevasses beneath the snow. WEAR A HELMET!

Are your riding companions trained and practiced in avalanche rescue? Everyone in your group needs to have a beacon, shovel, and probe, and know how to use them. Our mountains have very limited cell coverage, carry an emergency communication device and enough gear to spend the night.

Announcements

Forecasts are posted for Fridays-Sundays. Click the +Full Forecast link below for each zone to read more. Please submit your observations if you head out into the hills!