Run List: A Case Study
By: Justin Davis
A month ago, we published a blog entitled “Run List: A framework for tour planning.” As a follow-up to the original article (http://bit.ly/2U0uvXg), author Justin Davis presents a case study utilizing the run list approach.
JANUARY 24, 2018
I went up to Snoqualmie pass for a short morning tour with two buddies; we had to be back at work by noon.
We had received a substantial amount of new snow (Yippie!) The Northwest Avalanche Center rated the avalanche danger as considerable near and above treeline for the Snoqualmie pass zone. The avalanche problems for the day were wind slab and storm slab with snow continuing throughout the day. The “Bottom Line” in the avalanche forecast read:
“Dangerous avalanche conditions will persist Thursday, especially in terrain receiving wind transported snow. Avoid steep open slopes. Give safe margins near and below growing cornices. Storm snow is very deep! Tree-well and snow immersion hazards are very dangerous, so keep communication with your partner at all times. Storm layers will take extra time to stabilize.”
Detailed forecast that day for Snoqualmie Pass: http://bit.ly/2SfbPRV
Few observations existed from the previous days due to visibility. On the drive up, we built our run list.
THE RUN LIST
The Slot — RED — Even though it is my personal favorite line, this was an easy decision in the car. The run has obvious avalanche danger, but the approach has arguably even more exposed avalanche terrain, especially with wind loading.
Phantom — RED — Also an easy call, this a well-known avalanche path.
Phantom trees — GREEN, treed, therefore protected from wind and probably more anchored.
Kendall trees — GREEN, treed and lower angle.
Hyak (closed inbounds ski area) — GREEN — Lower angle, limited exposure to avalanche hazards.
THE DECISION
We chose Phantom trees.
Trail breaking was difficult and time consuming in the deep snow. Hasty pits and convex rolls showed no signs of instability. At about 10:30am we poked our heads out of the trees and eyed the slopes above. They looked sweet! Rules are rules, so no higher for us.
In the interest of science (not part of our decision making, our decision to turn around was already made), we dug a snow profile at 5150 ft. It revealed a right-side-up snowpack with 135 cm of storm snow above a saturated rain crust, going from fist to 4F to pencil in the rain crust (20 cm saturated crust). A compression test revealed a Q3 shear at CTM12 at 25 cm, we interpreted these results as indicating a fairly stable snowpack.
Mmmmm… those upper slopes looked good, but rules are rules. We ripped our skins and had some super fun tree skiing with some steep rollers and pillows all the way back to the cars.
We later learned that at 10:35am the NWAC forecast for Snoqualmie pass was updated (http://bit.ly/2SfOBv7) to include an observation from about one mile from where we skied:
“10:25 AM PST Update: Recent large-very large natural avalanche reported in Alpental Valley. Avoid exposure to higher terrain connected to large avalanche paths. Dangerous avalanche conditions will persist Thursday, especially in terrain receiving wind transported snow. Avoid steep open slopes. Give safe margins near and below growing cornices. Storm snow is very deep!”
Rarely do we receive positive reinforcement for good, informed decision-making. It would have been all too easy to take the results of our pit (extremely limited information) and extrapolate the safe results of that pit to meet our desire to ski another 12 turns higher onto that sweet open alpine slope.
It is more common to “get away” with poor decision-making in avalanche terrain, which leads to a false sense of mastery of avalanche forecasting. We failed to do a proper debrief, as we were rushing back to work, and we did not re-check the forecast on the drive home. Going forward, this would be a great thing to add to our tour plans.
Shout-out to Matt Schonwald for sharing photographs, route information and pertinent avalanche history in the Snoqualmie Pass area. Check out his awesome guide book: “Backcountry Skiing Snoqualmie Pass, Washington” (2017). Thanks also to Rob Coppolillo for editing and guidance.
