Meadows Blog

Anatomy of an Avalanche

In the early evening of Sunday, January 17, a hard slab avalanche approximately ¾ of a mile wide near the top of the Wy’East face at the 10,650 foot level on Mt. Hood fractured and slid. The “crown” or fracture line ranged in depth from approximately four to ten feet and the incident triggered slides into three different watersheds – White River Canyon (between Meadows and Timberline), Newton Canyon (to the North of our permit area) and most significantly Clark Canyon, just inside our permit area.

 Three drainages were affected by this avalanche event.

The avalanche continued down the Clark Canyon drainage depositing itself in the foothills area about 200 yards shy of the Heather Chair Lift. In total it traveled 2.75 miles, collecting several thousand tons of snow, ice and debris before exhausting itself. The pile of ice, snow, rubble and debris in the deposition zone ranging in height from 15 to 30 feet.

 Deposition zone near the ramp to the Heather Chairlift

The Hard Slab avalanche released naturally on an old crust that was formed just over a week prior. This event occurred above our permit area where no avalanche hazard reduction occurs. The conditions leading to this natural release were a hard ice layer formed from rain then a melt freeze cycle. This was followed by a storm cycle that deposited five to ten feet of wind loaded snow on top of this layer, including the moderate precipitation on Sunday.

The course and debris entered the ski area at the most remote part of our permit area, and at a time the terrain was closed. No guests, staff members or physical property was involved in this incident.

Avalanche Info

Avalanche starting zones generally occur on slopes between 30 and 60 degrees. They can run, and even accelerate, at pitches between 15 and 30 degrees especially when confined, such as the terrain in Clark Canyon. When the slopes hit 15 degrees or less the avalanche will generally decelerate to a stop, leaving huge amounts of debris in the deposition zone.

In terms of size, avalanches are measured on “R = Relative size to path” and “D = Destructive Force” scales –from 1 to 5, 5 being the largest and most destructive. Sunday’s avalanche was classified “R4” and “D4”.

Sunday's Avalanche Stats:

  • Slope distance travelled: 14,500 feet, 6,000 meters or about 2.75 miles from start to finish.
  • Elevation lost: 5,400 feet from the crown at around the 10,650 foot level to the “toe” at the 5,240 foot level.
  • Width of the starting zone: 3/4 mile wide.
  • Crown height at the fracture: Ranging from 4 to 10 feet
  • Deposition field is in the millions of cubic feet of debris with up to 15 to 30 foot depths.

Sunday’s avalanche is not as uncommon as originally reported. Since 1976 there have been 23 naturally occurring avalanches, R4 or bigger, in the Heather Canyon drainage. During this same time period, there have been 16 R4 or bigger events in the Clark Canyon drainage. The majority of these larger natural slides, in the Heather drainage, occurred prior to 2002. Since that time patrol has increased the frequency and effectiveness of avalanche hazard reduction in Heather Canyon. This has greatly reduced the number of large, natural avalanches in Heather Canyon. However, current reduction measures for Clark Canyon are a challenge because some of the larger start zones are above our permit area.

Looking down on Clark and Heather Canyons from SuperBowl.
This file photo taken from Super Bowl gives some persective and a "lay of the land" view of Clark and Heather Canyons. You can see the remnants of an avalanche track in Clark which is the more natural path of avalanches which start above our permit area.

Fortunately no guests, staff members or physical property was involved in Sunday's avalanche. This is an awesome display of nature that we respect, admire and learn from.

Coincidentally, January 16 – 22 is National Ski Area Safety Awareness Week. It is appropriate to focus on rule #6 of the Responsibility Code:

Observe all posted signs and warnings. Keep off closed trails and out of closed areas.

There are times that we close the gates to Heather Canyon, or portions of Heather Canyon, because of these conditions. We ask you to respect those boundaries, and never cross a rope line. The consequences can be deadly.

When heading into any of our gated access terrain – Heather Canyon, Clark Canyon, Private Reserve and Search & Rescue Cliffs, we highly recommend Skiing/Riding with a partner and carrying a beacon, probe, and shovel.

Enjoy the pictures – and let them serve as a reminder of just how awesome the nature of our mountain is. The pictures were taken by Executive Director of Mountain Operations Steve Warila, and Tighe Stoyanoff Head of Snow Safety. Thanks to Tighe and Nicholi Stoyanoff - Snow Safety, Patrol Director Melissa Toney and Patrol Manager Brandon Backman for their assistance in presenting this blog.

Also - kudos to our snow safety, patrol and grooming departments who were able to reopen lower Heather Monday before noon. Our groomers moved a lot of snow to create access back to the Heather Chair for our guests.

 Tracking the avalanche from Wy' East to Clark Canyon
The crown or fracture line is right at the top of the Wy'East face. The majority of the slab and debris slid down and was collected into Clark Canyon, typical of these slides which start above our permit area.

The avalanche track and deposition zone from Accordian Bowl
From Accordian Bowl, a patroller views the track leading to the deposition zone just before the cut off to the Heather chair ramp.

Fringe debris along the track
Working down off the flats below Accordion Bowl, encountering debris along the edge of the track left by the avalanche as it rounded a corner. An R5 may have taken those trees out as well.

The avalanche carved a berm as it richocheted off the bottom of Acordian Bowl
Notice the gouging of the earth by the avalanche as it passed through the flats of Accordion - the berm is between 25 and 30 feet high indicating the height of the avalanche at that point. 

 Massive debris - 5 foot high ice boulders
Measuring a five foot tall ice boulder with a rock encased in it.

 The 25 foot berm wall represents the avalanche depth at that point.
The Avalanche created this 25+ foot high berm or side cut as it smashed into the side of the canyon and altered course. 

 Deposition Zone
The berm is still pronounced and you can just barely make out the ramp up to the Heather Chair beyond the debris, which is almost impossible to ski through once it sets up into varying sized ice and snow clumps. The deposition zone ranged in depth from 15 to 30 feet.

 Looking at the deposition zone from the ramp to Heather chair
Looking back at the deposition zone from the ramp leading to the Heather Chair you can see the massive depth on the right hand side – that’s a 20 foot tall tree the snow is pushing over.

21 Comments

  1. Reed

    January 21, 2010

    Wow. I rode around this slide on Monday. Did anyone on the mountain witness it happening? Must've been really impressive!

    Meadows: No eye witnesses as it occured Sunday, most likely after dark during the storm.

  2. John

    January 21, 2010

    Thanks for posting this article - it is very informative and is a great reminder to your customers about why Heather stays closed longer than we like sometimes. 2 questions: is Middle Heather (like Memorial , Pluto etc) open now? (They were closed Monday morning.) If so, how are people navigating to the Heather chair since it looks like the slide filled up most of the usual runout to the chair. Thanks

    Meadows: As of this posting (12:40 PM Thursday) Heather is open from A-Zone on down. Our grooming crew did a great job grooming the run out.

  3. Yamo

    January 21, 2010

    The anatomy of an avalanche looks to be a lot more powerful than my own anatomy.

  4. B-ton

    January 21, 2010

    Amazing pictures and great write-up. Been looking forward to hearing your take on the slide. Mother Nature never ceases to show how amazing and powerful she is!!

  5. uprvallygrl

    January 21, 2010

    kudos to your grooming crew! the mountain has never looked better!

  6. geoff

    January 21, 2010

    Excellent report. Thanks for taking the time to assemble it.

    I am stunned that control work is not allowed on the slopes above the boundary. It's obviously a major hazard. We're incredibly lucky that this happened when the area was closed -- there would have been no survivors.

  7. Bob

    January 21, 2010

    A comment & a question. First, I think the "The course and debris entered the ski area at the most remote part of our permit area, and at a time the terrain was closed " glosses over the fact that Heather was open that afternoon and a slide a few hours earlier could have had much grimmer results. Luck played a huge factor in the timing of this event - the area was only closed because it was after hours, not because of preventive actions by staff.

    Now the question. Is Meadows allowed and does it perform avalanche control beyond its permit boundaries? Said differently, could Patrol have done anything to preemptively "control" this slide.

    Meadows: Our operating plan allows us to perform avalanche reduction operations only within our permit area.

  8. E-train

    January 22, 2010

    This is a great write-up and I'm glad to see it coming from Meadows Staff rather than an outside source. Transaprency with an event like this says a lot about an organization. Unfortunately all the idiots that say you guys keep lifts, and Heather closed so that patrol, and staff can schralp the powder won't even see it. I can't wait to come back to Meadows in the spring, and next season. I've missed it.

  9. Yam-Jr

    January 22, 2010

    Well said Yamo. I think - maybe a little too much info though.

  10. urp

    January 22, 2010

    thanks for posting the images and the story - amazing, the mountain is pretty powerful and deserves respect. I wanted to take my own pics but couldn't get a decent view of it. Thanks to the ski patrol for opening Heather on monday, it really made my weekend.

    So the groom crew has put a route over the debris? I can't wait to ski it tomorrow and check it out - MHM is great!

  11. k2skier

    January 22, 2010

    It was a humbling experience skiing in Heather on Monday. I'm shocked on how many parent took their kids in there! The one little girl loading before us needed a slow to get on, maybe it's just me but if you can't get on the chair at normal speed, Heather might be over your ability, please respect Heather parents.

    Heather is a double diamond run, but that run out was a triple diamond (no trouble for us but some of the kids and boarders were struggling), which leads into my question; what has been done to the run out? Will it be able to be where it normally is again this year? It doesn't seem feasible or possible to groom the avie debris.

    Meadows: We've groomed the run out - if you can make it down to the run out you shouldn't have any problems on the run out.

  12. Elliott

    January 22, 2010

    I was up at rainier on Monday and watched a huge slab release from about the 11,000' mark and it ran down about 3000' vert. Interesting that this happened the day before. NWAC had the avalanche danger at moderate that day. Any idea what NWAC said about Sunday? Thanks for writing this article up and posting so many pictures!

    Meadows: NWAC provides vital monitoring and forecasting services. But this isn't an exact science particularly with fast changing weather conditions at higher elevations. Their site advises always practicing safe route finding skills, being aware of changing conditions, and carrying avalanche rescue gear. Remember that avalanche danger rating levels are only general guidelines.
    There is a place on the NWAC site to report an avalanche - this is helpful information for NWAC and those who depend on it for information.

  13. Skiing Parent

    January 23, 2010

    To k2skier:

    "The one little girl loading before us needed a slow to get on, maybe it's just me but if you can't get on the chair at normal speed, Heather might be over your ability, please respect Heather parents".

    It's just you and no, that wasn't us in front of you. Little kids legs might not be long enough and they need to jump a bit to get on the older style chairs. Slowing them down just makes it a bit easier. My kid loves Heather (8 years old), and will probably be ripping A Zone next year. Skiing ability doesn't equal getting on a chair. No hard feelings, just a life long skier who learned this himself teaching his kid to ski.


  14. k2skier

    January 25, 2010

    Skiing Parent, Hogwash! I ran that chair, (when it was in it's original location) ,HRM, and any good lift op can get a child into a FGD (fixed grip double) without a slow. It's just not the slope angle that makes Heather an expert only area. I am a responsible parent and didn't take my son in Heather until he was 10 and could load the chair easily, by himself, at full speed, something every parent should think about.

    Be safe and make it fun!

    And there's usually much better snow elsewhere than Heather because of the slope and sun aspect, leeward terrain... (I'm speaking of A zone to Moon bowl, which is what most people go down). I see many people that don't belong in Heather and on Monday after the slide there were at least 4 kids who shouldn't have been in there.

    Sorry if I touched a nerve, but if the shoe fits...

    I would bet that Ski Patrol agrees with most of my opinions on this also, ask one sometime...

    Again, be safe and have fun!

  15. Skiing Parent

    January 25, 2010

    "Sorry if I touched a nerve, but if the shoe fits..."

    k2skier, did you not read this part of my post: "No hard feelings, just a life long skier who learned this himself teaching his kid to ski."

    I meant that comment, but since you decided to reply, so will I....

    "And there's usually much better snow elsewhere than Heather because of the slope and sun aspect, leeward terrain... (I'm speaking of A zone to Moon bowl, which is what most people go down)"....humm..isn't that part of Heather? Look all those fancy words up in a dictionary did you?

    " I ran that chair, (when it was in it's original location" --golf clap--

    "Hogwash" that chair must be pretty old with comments like that.

    Actually, a ski patrol said nice job to my kid....you lose your bet.

    Meadows: A spirited debate which we'll call a tie and conclude before it turns into road rage.

  16. airtime

    January 26, 2010

    Nice, informative story. great coverage and pictures!...Does Meadows have any plans on trying to get the Wy’East face and the "above permit" area controllable? And, what is the Avalauncher for?

    I think many of us would be crushed (sorry) if something wasn't attempted and explained to us in regards to control.

    I truely appreciate all of the efforts of the Pro Patrol and completely understand that it is not their fault, duty, or responsiblility to deal with matters involving Lease or Permit changes.

    This is not meant to be anything other than a question. thanks

    Meadows: We don't perform control work outside of our permit area and we aren't speculating as to whether that should change in the future.
    You mentioned the Avalauncher - that is a potato gun like remote delivery device used to "lob" explosive charges into areas for avalanche control work. We also deliver charges by hands, on tethers and with the Howitzer, which was put into service last season.

  17. k2skier

    January 31, 2010

    Skiing Parent, There was never any bet, or who's right or wrong here, just my son’s observations, not mine, of a mother requesting a slow for her young daughter. For some reason you took offense to my first post.

    Your sons good enough to get compliments from ski patrol, my words should have been like water off a ducks back. They were never directed toward you.

    On a serious note, if words like slope aspect and leeward terrain aren't in your vocabulary please pick up a snow safety book, like "Snow Sense-A Guide to Evaluating Snow Avalanche Hazard" by Jill Fredstone and Doug Fesler and have good a read. The more one learns about avalanches, the more avalanches should scare the informed, and Heather is an avalanche prime terrain.

    Have a great season, be safe and have fun!

  18. Ted

    February 22, 2010

    Skiing parents - I'm sooooooooo glad I don't live in Portland and have to listen to this competitive, self ranking crap anymore.

    Fascinating avalanche report and photos - well done.

  19. Berta

    March 27, 2011

    Interesting trail of messages regarding kids in Heather.
    My thoughts are that Heather is a dangerous place. There are height limits on carnival rides...If you're taking your kids in there, maybe they should be wearing a beacon and understand how to use it.

    Meadows: Thanks for the suggestion - which is good advice for all who enter the Canyon regardless of age.

  20. G@thenickels and M.A.N.

    February 15, 2012

    I love heather canyon! My favorite bowl is twilight bowl. It's awesome!

  21. kbljo

    April 16, 2013

    oh my god!whats the big deal if a kid rquestes a slow when loading the heather canyon chair! i mean if your kid can't load the heather chair than just take the flat road out to the hood river express! sheesh this isn't a big deal! not trying to be offensive just pointing out how silly this is.

Add a comment

  1.  
  2. Submit