Haines Avalanche Center

Forecast Expired - 12/26/2022

Above 2,500ftConsiderable

1,500 to 2,500ftModerate

Below 1,500ftLow

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:

New snow accumulation and Wind/Gusts : Around 10-16″ of low density cold snow with moderate N/NW-SE winds/strong gust will slowly transition to a warmer and more consolidated up-side down layer. This loose dry snow, or wind-packed soft slabs have a fast surface to run on over crusts and weak old snow. Expect this layer to be sensitive to human triggering in isolated terrain on slopes >30 degrees for upper elevations at-and-above treeline. Keep an eye out for unusual wind loading patterns, swirly winds and increasing temperatures. Look for signs of instability within the new snow including cracking, whumphing and natural avalanches.

 

The Bottom Line: New slabs are forming near the surface with increasing snow, wind and temperatures.  The slabs are on top a firm, slick bed surface from last weeks outflow.  It has been a very cold, windy week. Temperatures stayed between 0F and -17F for several days this week. The cold weather has only weakened our snowpack through increased facetting around our midpack crusts. The risk of deep, deadly avalanches is very real, and you should exercise extra caution and keep a wide safety margin. Travel one at a time to minimize exposure to slopes 30 degrees and steeper. Stay clear of trigger points (thin areas, rocks, small trees) where you can easily trigger persistent weak layers. If you find a trigger point, it will travel across slopes and trigger an avalanche in deeper areas.

 

Thoughts on Risk Reduction: We’re not getting much positive feedback from the snowpack and buried weak layers in the snowpack are getting worse. Surface slabs are quite hard right now, but temperatures are rising, and new snow is starting to pile up on top. Therefore the chances of triggering a destructive avalanche are slowly increasing. Your best bet to avoid a deadly avalanche is to reign in your expectations and lower your risk tolerance. Keep a wider-than-usual margin of safety by sticking to low-angle terrain, and giving dangerous areas a wide berth. There will be times later this spring when you can be more ambitious with the terrain… this is not the time.

 

 

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

Midpack Melt Layers and Crusts:

There is a serious weak layer about 60-70cm deep (The “Big Warmup” Layer, Formed Nov 17th). It is a thick refrozen crust with weak faceted snow above and below — easily visible in a snow pit. This is an unusual and unpredictable weak layer, so a wide safety margin is necessary. Slides could 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 big slide.

 

Observations in all zones throughout December have found moderate strength and easy propagation on failures within this 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 Formation:

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. The possibility of an avalanche stepping down to the ground will remain possible for several weeks at least.  We have a high-consequence early-season snowpack that deserves respect and should drive conservative decision making. Any slides that break to the ground are likely to be deadly.

 

Snow pit profile from Transitional zone 12/2.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

Early December brought a cycle of natural D2 wind slab avalanches in cross loaded gullies in the Transitional and Pass zones. These were on SE, E, and NE aspects above treeline:

(Click to enlarge)

 

Weather

Forecast:

Frigid temperature and strong NW winds on Friday will slowly ease as moisture enters our area to produce light to moderate snowfall Friday through Monday. Total 4-day snowfall is expected to be around 8-16″. Expect temperature to remain in the low teens to single digits as northerly outflow continues, with a slight warmup Sunday-Monday.

Recent Weather Summary:

  • Dec 16-23 brought strong NW winds and arctic cold temperatures
  • Dec 15 brought warmth/light rain up to 2600ft.
  • 4″ of snow fell Dec 12 in the Lutak zone, SE winds were quite strong
  • There was a strong and cold NW wind event Dec 9 and 10
  • A storm on Dec 7th brought 17″ of snow to the Lutak zone and 7-10″ to the Transitional/Pass zones
  • Strong inversion on Dec 3 warmed higher elevations (38F Glacier Creek, 4800ft)
  • An arctic outbreak brought very cold temperatures and strong NW winds Nov 27-Dec 2nd
  • Complete Season Histories:     Transitional Zone     Lutak Zone
 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 @ 2,500′  62″  1″ / 0.05″  11″ / 0.60″   0′ moderate, NW   10″ / 0.70″*
Flower Mountain @ 2,500′  30″  2″ / 0.10″   2″ / 0.10″  0′ moderate, NW   10″ / 0.70″*
Chilkat Pass @ 3,100ft  4″   2″ / 0.10″   2″ / 0.10″  0′ moderate, NW   5″ / 0.35″*

( *star means meteorological estimate )

Additional Information

It’s time to start thinking avalanche. Dust off your gear and make sure it is fully functional. Put new batteries in your beacons! Do a beacon practice to start the season and keep your skills fresh.

If you head into the hills, watch out for avalanche prone areas, and be especially careful of rocks and hidden hazards like crevasses beneath the snow. WEAR A HELMET!

Announcements

Forecasts for the 2022/2023 winter season will be 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!