Don’t mess with the “Brown Frown” — Glide Avalanche Problems in Alaska’s Southcentral
by Aleph Johnston-Bloom (Chugach National Forest Avalanche Information Center Forecaster and AAS Instructor)
“Good Morning, this is Graham Predeger with the Chugach National Forest Avalanche Information Center with your snow and avalanche conditions for Tuesday January 12th at 7 am. The Primary Concern today is Glide Avalanches. It’s not everyday that our avalanche problems are so obvious and visible to the naked eye, but that seems to be the case today. Found on all aspects, glide cracks are mostly relegated to the 1,000’ — 2,500’ elevation band. Glide cracks are strange beasts that really are impossible to predict. Weather and other triggers such as humans, or even explosives, that we associate with other dangerous avalanche problems don’t seem to affect glides. There is no discernable pattern to predict a failure, as they tend to fail naturally and on their own schedule. Sometimes a glide crack won’t release at all, and benignly just fill back in with snow. Knowing when or even whether a glide crack will avalanche is like asking is there “Life on Mars?” Maybe, though the jury is still out so in the meantime, take your protein pill and put your helmet on!
Glide cracks are best to be given a wide berth. Limit your exposure time underneath, and if skiing or riding in terrain with glide cracks, try and map them out first as not to end up directly on top of or inside one. Remember, when these do fail, they tend to be destructive, failing to the ground bringing the entirety of the snowpack with them.”
Glide avalanches as the Primary Concern? In January? The day after David Bowie died…
Several years ago when the avalanche problems and icons were being discussed in the avalanche community, there was talk of not needing a glide avalanche icon. Here in Southcentral AK, we are glad that it made the cut. It has been used in our forecast product for the past 7 weeks, and has been the primary concern on many days.
Following a warm storm pattern over the holidays that deposited over 14 ft. of snow, glide cracks started appearing throughout the mid-elevations from Girdwood Valley to Turnagain Pass and beyond. The term ‘littered’ has been used more than once to describe the widespread cracking of the snowpack. The forecast area has seen glide cracks in previous Januarys but this year’s cycles have been unusually active. There have been three major spikes in activity so far.
One thing is for certain — it has added an interesting twist to evaluating and communicating the avalanche hazard to the public. One LOW danger January day we had a large glide crack release in the heart of our most popular snowmachine zone, the next day we bumped the danger to MODERATE for glide avalanches and indeed another released.
The meat of the problem is cracks continue to appear and occasionally release in terrain that people recreate in. Watching how recreationalists treat glide cracks has been almost as interesting as watching them pop.
Public observation on 1/8/16: “Toured up usual skin track on Lipps and observed two sizable glide cracks on the south face, above 3000′. One guy from a group above us decided to jump into it and measured it 5–6 ft. deep to the ground. Also observed a large glide crack on the south face of the peak directly north of Lipps.”
Glide crack with tracks on Lipps Ridge, 1/6/16. This crack released 5 days later.
Public Observation 1/14/16: “The staff has been warning about the dangers of ‘Glide Cracks’. I am very familiar with the Lipps area, and the glide cracks on it. I have no memory of the glide crack releases on Lipps having so much destructive force. They ran much farther than usual, the size of debris is much larger than usual, and the amount of energy is way above usual. Just crossing the debris field was an exercise in humility. I have been watching many glide cracks over the last couple weeks, most in usual spots, but I felt the need to warn others about these results.”
Public Observation 1/15: “Touring up to Tincan Proper our group of 4 observed a glide crack release across the valley on the Eddies wall. The Eddies wall is currently littered with glide cracks all at a similar elevation. My estimate is 2000ish feet. The release was very audible. The crack that pulled out is pretty far down the wall. Dirty snow ran toward the valley floor.”
Tracks and Cracks. This is on Tincan Ridge, and to date, these cracks have not released.
In talking to long time locals and professionals we have heard some additional anecdotal ideas about this current glide situation.
Dave Hamre — (Alaska Railroad Corp., Avalanche Program Director):
“Ah, good luck with that”
Scott Hilliard — (Alyeska Ski Resort, Snow Safety Director):
Glide-induced avalanches are every forecaster’s nightmare. I think we have a solid understanding of the ground/interface mechanisms at work. The problem is that, like cornice falls and serac falls, the delayed and indirectaction nature of these hazards makes it impossible to predict with any certainty when or if they will release. The only good news is that a cycle of glide activity will eventually be followed by cycle of inactivity, but that may come fairly quickly, or not until the final spring meltdown.
Here at the Resort, our current glide cycle is significant in that among the numerous glide cracks that have appeared, we have had two actual glide avalanche releases to date, which is relatively rare during midwinter. While this activity is not unexpected we are well above average in the water content and temperature of our snowpack it is nonetheless difficult to guess when the cycle may end.
Jim Kennedy — (Alaska DOT Avalanche Program Director):
“They are a pain in the ass and give them room.”
Andy Morrison — (Owner/Operator, Alaska Backcountry Access, snowmachine guide service):
After 15 years of taking clients out at Turnagain Pass — “I have never seen a glide avalanche problem like this, at this time of year. I really think it has to do with warm temperatures and the ground not freezing as hard as it usually does. There is a lot of mud in the glide releases. Watching them release with cold temps and warm temps has emphasized the unpredictability.”
So, are there any themes to this season’s glide activity? Although we are not jumping to any conclusions, and have some data analysis ahead of us, cracks tend to appear during warm stormy weather but it is not until afterword, with minor cooling and clearing, that boom… the brown frown fails. Not even a 7.3 magnitude earthquake January 24th was able to rattle any of these loose — go figure. It is a fascinating phenomenon that really may all tie in with David Bowie…
Alaska Avalanche School, 2016
