Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Nate Hough-Snee, Lexine Long
Observation Date:
February 24, 2023
Submitted:
February 24, 2023
Zone or Region:
East Central
Activity:
Skiing/Snowboarding
Location:
Johnny Creek

Observed Avalanches

Did you observe any avalanches? 
Yes
Avalanche Type:
Dry Loose (Sluff)
Size:
Size 2: Could bury, injure, or kill a person
Elevation:
6000'
Aspect:
S
Comments:
As the day's temps moderated, solar rock bands began to shed their snow, triggering pretty large natural sluffs in very steep to extreme terrain. Mostly along steep solar cliff bands, although we noticed a few on north.

Signs of Unstable Snow

Did you see shooting cracks? 
Yes, Isolated
Did you experience collapsing or whumpfing? 
No

Observations

Clear and calm at the trailhead late AM. Cold (single digits F) and light easterly winds gave way to slightly less cold (teens F) and moderate westerly(SW) winds on the solar ridgeline we travelled. We had a snack and quick dig at 6100' SW/S:

HS 145-160cm with wind affected HST somewhere in the 30-40cm range.

We got an elusive and rarely seen in the wild CT1 on a pencil hard wind slab 15cm down (sudden planar shear). This same layer cracked with every turn for about 600' of skiing on the same SW aspect. More alarming was that in the progression, we also got a CT13 80cm down with a sudden planar shear on large facets below a crust (MLK crust?).

ECTP15 15cm on the wind slab and ECTP20 45cm down on the crust before last weekend's storm.

Generally I was surprised by the shallow snowpack near ridgeline on southerly aspects, which is a testament to our relatively mild and high pressure-laden February. This HS also speaks to the strong winds we've had with most recent storms.

Mid-slope in the BTL and even up to the NTL on true south, the bases of trees are melted out and bare. There is a dust on crust ski quality below 3200'.

Based on where we dug, it seems like we have plenty of weak snow in the 'pack at present, although it isn't presenting under foot beyond the recent and shallow wind slabs.

With moderate winds and moderate transport visible across the valley in the Stuart Range today, committing ATL features may not be as straightforward as we'd hoped for weekend travel.

Media

One of several DL-N-R1-D2 (or D1.5) that we saw today on southerlies and wind-affected northerlies.

Advanced Observations

Observed Avalanche Problem #1: 
Wind Slab
Comments: 
We experienced widespread cracking in the ATL on both westerly and easterly aspects. Winds were moderate WSW at 1400 at 6000' after easterly winds dominated the AM hours. Widespread wind loading has occurred on anything E or W along N-S ridgelines.
Observed Avalanche Problem #2: 
Cornice
Comments: 
We noticed a few small mid-slope wind features and ridgeline cornices that had popped in the wind and sun, triggering loose avalanches. Seems like some cornices failed last storm and are rebuilding (like Big Slide Peak).
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