Date of Observation: 04/22/2023
Name: Evan Ross
Zone: Northwest Mountains
Route Description: NE-E-SE 9,500-11,500. Purple Ridge Area.
Observed avalanche activity: Yes
Avalanches: At 1pm, wet loose avalanches were reactive on NE and E below 11,300ft. These were generally small, but where they could run and accumulate mass they became large in size. We skier triggered several small wet avalanches and one become large in size. Another party had triggered more wet avalanches in similar terrain.
Weather: Convective snow showers with some moderate winds and drifting snow during those periods. The greenhouse was in full effect.
Snowpack: Recent storm totals were around 20 to 25cm at 11,000ft. Less snow at lower elevations and more snow at higher elevations… On the lee side of Purple Ridge, the drifts were a couple of feet thick. It was difficult to assess how far the thicker drifts extended into the slopes below. Wind slabs felt stubborn, but there was a notable lower-density layer of snow near the bottom of the drifts.
Snow surfaces become moist to wet on the sunny aspects, and thick/moist on northerlies BTL.
Photos:
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[accordion_item title=”Avalanche Report #1″ parent_id=”my-accordion” open=”false”]Estimated avalanche date: 04/22/2023
Number of Avalanches: 5
Location
Location: Upper Slate (Purple, Yule Pass, Paradise Divide)
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: E
Characteristics
Trigger: Skier
Trigger modifier:
Type: Wet Loose
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:
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[accordion_item title=”Avalanche Report #2″ parent_id=”my-accordion” open=”false”]
Estimated avalanche date: 04/22/2023
Number of Avalanches: 3
Location
Location: Upper Slate (Purple, Yule Pass, Paradise Divide)
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: NE
Characteristics
Trigger: Skier
Trigger modifier:
Type: Wet Loose
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:
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[accordion_item title=”Avalanche Report #3″ parent_id=”my-accordion” open=”false”]
Estimated avalanche date: 04/22/2023
Number of Avalanches: 1
Location
Location: Upper Slate (Purple, Yule Pass, Paradise Divide)
Location Specific:
Start Zone Elevation: BTL: Below Tree Line
Aspect: NE
Characteristics
Trigger: Skier
Trigger modifier: Unintentional
Type: Wet Loose
Failure Plane:
Size
Relative Size: R1 very small
Destructive Size: D2 – could bury, injure, or kill a person
Avg. crown height (inches): 7
Avg. width (feet):
Avg. vertical run (feet): 600
Involvements
# of people caught:
# of partial burials:
# of full burials:
Additional comments:
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