Date of Observation: 03/04/2023
Name: Zach Guy
Zone: Northwest Mountains
Route Description: Traveled on various aspects of Mt. Owen and Mt. Afley to 13,000′, mostly N/ATL.
Observed avalanche activity: Yes
Avalanches: A notable amount of avalanches in the new snow ran overnight, D1 to 1.5, with a couple long running slides approaching D2 in size. These appeared to be a combination of loose snow avalanches and soft slabs of wind drifted snow, on all aspects above treeline.
Conditions were relatively quiet today, I was able to ski trigger a small wind drift and get some shallow sluffs.
Weather: Thin overcast with enough solar to moisten some sunny slopes. Light winds most of the day started ramping up around 2 p.m. At 3p.m. we were on top of Afley and immersed in intense blowing snow and whiteout conditions during strong gusts.
Snowpack: 24-hour storm totals ranged from 10″ near treeline to 16″ in sheltered terrain above treeline! Low density with signs of wind drifting in the more exposed terrain. I produced some localized cracking in those drifts, up to 18″ thick or so. We observed one collapse on a west aspect near treeline of Afley Peak, estimated about 18″ deep on some older facet/crust layers.
Fetches were blown dry at ridgetop from last night’s winds, but there’s still plenty of loose snow available for transport (10-15″) further downslope in alpine fetches or in less exposed near treeline terrain for tomorrow’s winds to work with.
Photos:
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Cracking in a 16″ thick wind drift near treeline.
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A southwest facing fetch with 10″ of loose snow available for transport.
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A skier triggered wind pocket on a small terrain feature.
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Mt. Owen. Fetches near ridgeline were scraped dry by last night’s winds. The larger fetches lower down the slope held about 10″ of soft snow that will easily be transported by tomorrow’s winds.
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Fresh debris from what looked to be a wind slab off the south side of Mt. Owen
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Fresh debris from a long running sluff or wind slab on the west side of Mt. Owen.
Estimated avalanche date: 03/03/2023
Number of Avalanches: 2
Location
Location: Lake Irwin (Robinson Basin, Owen, Ruby)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: S
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
Size
Relative Size: R1 very small
Destructive Size: D1.5
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: Likely long running wind slabs entraining loose storm snow on south face of Owen. Almost reached Green Lake. Failed either late 3/3 or early 3/4.
Estimated avalanche date: 03/03/2023
Number of Avalanches: 2
Location
Location: Lake Irwin (Robinson Basin, Owen, Ruby)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: SE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Soft Slab
Failure Plane:
Size
Relative Size: R1 very small
Destructive Size: D1- Relatively harmless to people
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: wind slabs entraining loose storm snow on southeast face of owen. Failed either late 3/3 or early 3/4.
Estimated avalanche date: 03/03/2023
Number of Avalanches: 4
Location
Location: Anthracite Creek (West side of Ruby Range, Marcellina)
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: W
Characteristics
Trigger: Natural
Trigger modifier:
Type: Unknown
Failure Plane:
Size
Relative Size: R1 very small
Destructive Size: D1- Relatively harmless to people
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: West side of Mt. Owen. Guessing loose snow avalanches. Maybe soft slabs. Failed either late 3/3 or early 3/4.
Estimated avalanche date: 03/03/2023
Number of Avalanches: 2
Location
Location: Oh-Be-Joyful Basin
Location Specific:
Start Zone Elevation: ATL: Above Tree Line
Aspect: NE
Characteristics
Trigger: Natural
Trigger modifier:
Type: Unknown
Failure Plane:
Size
Relative Size: R2 small
Destructive Size: D1.5
Avg. crown height (inches):
Avg. width (feet):
Avg. vertical run (feet):
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments: NE side of Purple Peak out of the couloirs. Debris ran over mid-bench almost to Blue Lake. Could have been D2s, didn’t have good enough vis.
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