Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
April 15, 2023
Submitted:
April 15, 2023
Observer:
NWAC Forecaster - Irene Henninger
Zone or Region:
West North
Location:
Bearpaw (2500-6000ft, all aspects)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

The new snow layer from earlier in the week was well bonded to the underlying crust. Subtle failures were noted about halfway down the layer, which were likely where slab avalanches occurred with a human trigger a couple days ago.
A surface crust on a south facing aspect at 5900’, which occurred due to variably sunny skies in the last 3 days.
Wet loose avalanches which occurred in the last few days in the previously low density dry snow on the southern half of the compass. Canyon Creek area.
A 10+cm thick crust from last weekends warm wet event. This is even present at 5600’ on a north facing aspect.
Shallow slab avalanches on steep slopes which failed sometime in the last few days with a human trigger. West-facing, 5700’ Canyon Creek.
Wet loose avalanches which failed on steep slopes on the southerly half of the compass within the last few days with the sunny skies. Canyon Creek.
Shallow slab avalanches on steep slopes which failed sometime in the last few days with a human trigger. West-facing, 5700’ Canyon Creek.
Large cornices in Canyon Creek, east-facing, 6000ft.

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Calm

Broken skies transitioned to overcast by late morning and flurries began around noon. Light-moderate snow was falling at our departure at 1400hrs. Snowline was around 3500ft. Only wind was light southerly noted along ridgeline at 6000ft.

Saw several shallow (6"?) D1.5 soft slab avalanches, snowboarder triggered, on westerly aspects ~ 5700ft on very steep terrain, which likely occurred 4/12-13. In the same basin, and several other locations, wet loose avalanche on south, east and west aspects up to size D1.5 (medium) naturally occurred, also suspected of occurring in the 4/12-13 time range.

Snowpack Observations

An overnight freeze was present down to our lowest elevation at the start of the day. Upon return, snow was moist below about 3500ft. Crusty snow surfaces were present all day above approximately 4500ft in all areas except for true north above about 5000ft. Crusts ranged from about 2" thick to just barely detectable on slightly off north aspects. Thicker areas of the crust made snowmobiling a little more challenging but it still wasn't too difficult on a sled.

Above 5000ft there was about a foot of snow above last weekend's very thick crust. The crust was over 10cm thick on a north-facing aspect at 5600', so everywhere we traveled it was very substantial. Occasionally on steeper slopes we noticed it on the sleds, but overall the foot of snow had become a little heavier and the crust generally wasn't detectable.

Several quick pits and tests everywhere we traveled above 4500ft found the new snow layer well bonded to the underlying crust. Slight weaknesses were detected about 15cm down, midway in the new layer. This is likely where the previous slab avalanches occurred, although the layer appeared to be less reactive by today. Snow crystal id only found decomposing forms throughout the whole new snow layer.

Overall a pleasant day out despite the variable snow surfaces.

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