Issued by Drew Hardesty for Sunday, February 17, 2019
A strong MODERATE DANGER exists on heavily wind loaded slopes at the mid and upper elevations. The danger is most pronounced on upper elevation northerly through easterly facing terrain. Cornices are an issue - Exercise great caution along and underneath the heavily corniced ridgelines.
Safe Travel Protocols are critical: one at a time, get out of the way at the bottom, have a plan.
The accident reports for the four avalanche fatalities are all finalized with some first-hand accounts and worth reading. We all have something to learn so that we can get home safely to our loved ones.
The latest UAC Podcast was just released: The Message and the Messengers - A Conversation with Alex Hamlin. In this podcast, we talk about the psychology behind marketing (and influencing behavior change), with a particular eye toward marketing safety. We talk about what storytelling means as a way of establishing connections and meaning - as this was central to his philosophy in producing and directing the exceptional BDTV series from a few years ago.
Skies are partly cloudy with temperatures in the single digits.
The winds defied expectations yesterday and some might even say overachieved. They blew 15-25mph from the west and northwest with gusts to 50 up high but have largely settled down and are now generally less than 10mph from the southwest.
Snow depths are 110-135"+ in the upper Cottonwoods and 75-90" along the PC ridgeline. The Ogden and Provo mountains boast (and I mean boast) snow depths of 95" (and - mind you - these snow stakes are at 7500'-8000').
Wind, periods of sun, and localized riming had their way with the snow surfaces and you'll find both excellent and variable conditions in the mountains with the most consistent riding in the sheltered mid-elevations.
A large trof of low pressure cradles the entire western US. A couple weak systems rippling through will keep us with cold temps, light winds, and occasional light snowfall for the upcoming week.
Recent Avalanches
We heard about three wind slab avalanches triggered in the backcountry that involved one near full burial and quick live recovery by his partners. A skier triggered a 1-2' deep and estimated 200' wide avalanche in the Guardsman Pass area on a steep east facing slope at 9400'. His partners had 'eyes-on', as we say, and - because they were ready and had the gear - were able to unbury him quickly. We hope to have more info today. The three avalanches below:
Guardsman Pass 1: 9400' ENE - 1-2' deep and 200' wide (video below)
Guardsman Pass 2: 9000' ENE - 1' deep and 40' wide skier triggered pocket
Cardiac Bowl: 10,800' NNE - estimated 1' deep and 80' wide (pc: Stefankowski/observation M. White)
Of other interest, sluffing of the low density snow noted in the steepest terrain. Also, a party walking the Cottonwood ridgeline near Davenport Hill unintentionally triggered a very large (est two SUVs) hard slab cornice onto the steep rocky terrain below.
THANKS TO ALL FOR REPORTING INFORMATION: YOUR INFORMATION HELPS SAVE LIVES.
Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
New and old wind drifts exist on many aspects now at the mid and upper elevations. Some are stubborn and hard; others are shallow and soft. All are gaining strength and stability but steep wind drifted terrain should continue to be avoided for another day. The usual bag of tricks for soft wind slabs do not work effectively for hard wind slabs. In other words, cornice drops and ski cuts can be misleading at best and dangerous at worst. I imagine we'll have a couple more human triggered wind drifts to talk about tomorrow. The majority of these drifts are in upper elevation northerly through easterly aspects but others are scattered around the compass in the mid-elevations due to terrain channeling.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Human triggered large avalanches into much older snow layering 3-6'+ deep are possible in isolated areas. In general, these avalanches probably need to be triggered by a heavy load such as a cornice fall, new snow avalanches stepping down to older layers, or an explosive. Or being unlucky enough in finding the thinner trigger spot in the slab. Terrain that has avalanched previously (repeater slopes) or other thinner snowpack areas are not to be trusted. Cracking and collapsing rarely play a role here. A very large natural avalanche into old snow released naturally (cornice fall?) in the upper Icebox of Main Porter Fork (9400' NE) on Thursday (est) that has been described as a 25 year event pulling out 6' deep and 500' wide, that probably left a few cords of firewood in the debris. More recent natural avalanches into old snow have been noted in the Mill Canyon Peak area (see Provo forecast).
Avalanche Problem #3
Cornice
Type
Location
Likelihood
Size
Description
CORNICES ARE ENORMOUS. Most of these are too large to intentionally drop onto a slope below. They will break back farther than you think, well back from the apex of the ridgeline. 5% of our avalanche fatalities in Utah have involved cornice fall. Exercise great caution along and underneath the heavily corniced ridgelines. See pic from yesterday below that shows in great detail what the consequences might be for going over with the box car. (pc: Murray)
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.
