Haines Avalanche Center

Forecast Expired - 12/11/2022

Above 2,500ftConsiderable

1,500 to 2,500ftModerate

Below 1,500ftLow

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Wind Slab:

The Bottom Line: Northwest winds will cause new snow to drift into fresh wind slabs 1-2ft thick specifically above treeline on S-SE-E aspects.  Lookout for recently loaded slopes and identify terrain features such as gullies, ridglines and convexities. Travel one at a time to minimize exposure clear of runout zones, or possible trigger points. Deeper weak layers have not had time to heal and surface avalanches, or the right trigger point could step down to produce a larger slide (See Persistent Slab problem below).

Wind loaded slopes and cross-loaded gullies should be avoided. You can tell if a slope is wind loaded by the filled-in, or rounded shape of the snow. Probe around for hollow, slabby surface snow. Look for recent signs of loading, wind transported snow, or flagging.

 

Rocks and other early season hazards will be a major safety hazard as well, so take it slow and easy, and keep your avalanche eyeballs on, especially in wind loaded areas and convexities. Be careful to avoid terrain traps where snow could pile up quickly. Even small slopes can have big consequences.

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

Thoughts on Risk Reduction: Let’s take a step back. We now have a few serious weak layers deep down in our snowpack that you do not want to trigger. These weak layers have not had time to heal. 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.

 

Midpack Melt Layers and Crusts:

There is a serious weak layer about 20-60cm deep (The “Big Warmup” Layer, Formed Nov 17th). It is a thick refrozen crust with weak faceted snow above and below. This is a difficult to predict and an unusual weak layer, so a wide safety margin is necessary. Slides could break further than expected from a shallow trigger point such as rocks, trees, or cliffs. You could ride the same slope numerous times until that right spot produces a big slide.

 

Observations from the Chilkat Pass zone on 12/4 found moderate strength but 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 (or 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. As the snow gets deeper, the load over this weak layer at the base increases, along with unpredictability. This is becoming a high-consequence early-season snowpack that deserves respect and should drive conservative decision making.

 

Snowpit profile from wind loaded area on Nadahini on 12/4:

 

Likelihood:

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

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

We have had reports last week of natural D2 wind slab avalanches in cross loaded gullies.

Photos from last week at the Pass, E and NE aspects at 3200ft:

(Click to enlarge)

 

Weather

Forecast:

A northerly outflow wind event has ramped up and will continue through the weekend with clear skies and moderate to strong winds. Daytime temperatures at lower elevations will drop into the low teens, while alpine temperatures reach below zero. Expect the wind chill to be severe.

Seasonal Summary:

  • A storm on Dec 7th brought 17″ of snow to the Lutak zone and 7-10″ to the Transitional/Pass zones
  • An arctic outbreak brought very cold temperatures and strong NW winds Nov 27-Dec 2nd
  • Nov 20-25 brought about 2ft of new snow above 2000ft (about 1ft in the Pass zone)
  • Mid November was very warm, with temperatures reaching over 40F at 5000ft
  • Cold weather set in Nov 4th – 9th, with alpine temps down to 8F at times
  • A NW wind event Nov. 6th blew away much of snow in exposed areas
  • 2 to 3ft of snow fell in Early November down to sea level
  • October 26-27th brought in 5-12″ of heavy wet snow above 1500ft
  • The first layer of snow to remain into winter fell above 3,500ft on Oct 21st. It was 6-12″ deep.
 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′  58″  1″ / 0.10″*  17″ / 1.50″*   0′ mod, NW   0″ / 0.00″*
Flower Mountain @ 2,500′  33″  0″ / 0.00″  10″ / 1.00″  0′ mod, NW   0″ / 0.00″*
Chilkat Pass @ 3,100ft  3″  0″ / 0.00”  7″ / 0.33″  0′ mod, NW   0″ / 0.00″*

( *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!