Observation: NWAC Forecaster

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Basic Information

Observation Details

Observation Date:
April 12, 2023
Submitted:
April 12, 2023
Observer:
NWAC Forecaster - Irene Henninger, Lee Lazzara, Kris Stemmler, Hilary Groh
Zone or Region:
West North
Location:
Baker NRA (2000-6500ft, S-E-W)

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

6000ft, S at the Baker NRA. Storm snow was very well bonded to the underlying 4/10 crust.
Dry, low density snow fell 4/10-4/11. It was moderately wind affected here at the Baker NRA. Above ~5500ft it was closer to a foot, the entire snowpack was dry, and the underlying 4/10 crust was thick and solid. Down lower, the underlying crust was only a couple inches thick and punchy on feet, and the snow beneath that was moist.
Wind gusting strong for a few hours midday 4/11 produced small- and very small- natural avalanches.
Wind-effect was very noticeable at the Baker NRA. the further you went up the more obvious it was. Here, the arrow points to spots that were stripped back to the 4/10 crust, with low density yet wind-affected snow on either side. This one was more easily noticed due to the tracks and lack of tracks.
We suspect that midday 4/11 SW winds gusted strong for a short time and wind-effect produced small slab avalanches and this unusual crossloaded wind feature on the Railroad Grade produced a small avalanche. Several small partially filled crown lines were visible in the area.
This photo was at 9am- low density and dry snow on top- but when we came back through at 1:30pm it had consolidated to about 10cm and was moist.
Old avalanches which were likely wet loose and possibly ran Sunday during the very moist period. Schreibers, 4300ft, E
Large slab avalanche on the east face of Seward Peak above the Deming Glacier on Baker. Likely triggered by a loose snow avalanche from above.
Small natural wind slab avalanche (on the farther ridge on the left), D1 on a southwest aspect at 6200'. Probably released during a period of stronger winds on Tuesday morning. A bit of a fresh cornice formation over the older melted down cornice visible in the foreground.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Calm
New/Recent Snowfall:
25cm

Clear skies through mid morning progressed to broken skies and patches of low lying clouds with a cloud level of about 5000-6000ft by midday. Intense sun was hot! By 1300hrs a few snowflakes began falling.

Old D1 slab avalanches were visible on steep rolls, beneath cliff bands and small cornice features. We suspect the avalanches ran mid-storm, midday yesterday, likely when winds were gusting strong for a few hours. They were partially filled in. We suspect crowns were ~6” to 1ft.

Extensive slope testing by others out enjoying the low density snow didn’t yield any avalanches to our knowledge. A couple very small wet loose slides were noted around 5500ft on SE aspects midday.

Snowpack Observations

Patchy old snow was present at 2000ft, and 3/10-11 storm snow began at about 3000ft, and was a dry, low-density 6” by 3500ft.

From about 5000ft and up the snow was variable due to wind-effect, although it was still dry and low density, and mainly averaged just under a foot deep before you encountered the underlying 4/10 crust.

Beneath 5000ft, the crust was only a couple inches thick, and punchy when you got off the sled. At higher elevations the crust was thicker but snow was dry beneath the ~10cm crust where I dug at about 6000ft. We found the new snow layer was well bonded to the crust.

Upon our return to Schriebers Meadow at 3500ft at 1pm, the snow was moist, even though it was on a flat surface.

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