RobStrickland

SubjectUpper Yule Creek
Date01/12/2022
Forecast ZoneNorthwest Mountains
Route Description

We started low at Slate River TH, but mainly traveled in the upper Yule Creek area between 12,800 and 10,800 on W to N to E aspects.

Did you see any avalanches?Yes
Avalanches

No new avalanche activity. A few more old avalanches that have not been documented. With closer inspection, we decided that the previously documented avalanche that spanned between Purple and the Blob was another D4 from the holiday cycle. Just another impressive avalanche from that cycle.

Weather

Thin clouds creating partly cloudy sky. Steady moderate winds in the alpine, primarily from the W-NW in the morning and more NE in the late afternoon.

Snowpack

In the alpine, the wind was transporting snow throughout the day. However those winds were creating more variably snow surfaces and wind effect, then they were actually creating new wind slabs. In those same areas, we were also managing old hard slabs that have been created over the last couple of days by recent winds. These slabs were hard, only a few inches thick, and stubborn, but ready to take you off your feet in terrain that you wanted to stay on your feet.

Between Purple and the Ant, there are few places that the snowpack wasn't altered by the holiday avalanche cycle. We did travel in steep terrain on slopes that didn't appear to have previously avalanches, but most of the terrain traveled had previously avalanched or had old avalanche debris, all of which has been covered back up by new snow in January. West and Northwest aspects held more trigger-points or areas that the snowpack would go from shallow to deep abruptly. Surprisingly we made some of our best turns on a steep NW aspect starting below about 12,600ft and just below all the windblown snow surfaces near the ridgeline.

All in all for the deep persistent slab avalanche problem we chose to reduce our risk by managing trigger points vs slope angles.

Detailed Avalanche Observations
Estimated avalanche date12/31/2021
Number of avalanches1
LocationUpper Slate (Purple, Yule Pass, Paradise Divide)
Start zone elevationATL: Above Tree Line
AspectNW
TriggerNatural
TypeHard Slab
Failure planeOld snow
Relative SizeR3 medium
Destructive SizeD3 - could destroy a car, wood-frame house, or snap trees
Additional Comments

Blob NW side

Detailed Avalanche Observations
Detailed Avalanche Observations
Detailed Avalanche Observations
Detailed Avalanche Observations