Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

February 5, 2023

Submitted:

February 5, 2023

Observer:

NWAC Forecaster - Josh Hirshberg

Zone or Region:

East North

Location:

Hwy 20- Rainy Pass (NE-SE 2,300-6,990ft)

Recent Avalanches?

Yes

Cracking?

None Experienced

Collapsing?

None Experienced

Above treeline on the ridge between Lake Ann and Rainy Lake, 6,700ft.

Feb 3rd interface. New snow buried a variety of surfaces including near surface facets. Rainy Lake, 6,650ft, SE

Clean and planar tilt test on the new/old snow interface that was buried on Feb 3rd, ~1ft below the surface. Small facets were observed on the surface prior to the storm. SE, 6650ft, Rainy Lake.

Cornices hang over a steep, north slope. 6,000ft, Lake Ann, Rainy Pass.

Advanced Information

Cloud Cover:

Overcast

Wind:

Calm , W

New/Recent Snowfall:

~20cm depending on location and elev

More clouds west of WA Pass. Cloud cover ranged from broken to obscured w increasing clouds thru the day and brief periods of lifting clouds and improving visibility throughout. Intermittent, light S-1 snow all day. Only light, west gusts at 7,000ft, above treeline.

Avalanche Observation Comments:

The only observed recent avalanches were small loose dry, point releases. One triggered slide and one natural. Both occurred on very steep (>40deg), northerly slopes, involving the top 5-10cm of new snow. While small and not much snow to entrain, these were long-running slides.

Overall, found a good bond at the 2/3 new/old snow interface ↓~20cm. Many hand pits did not produce planar shears at this interface. We skied NE-SE slopes up to 40 degrees from 7,000-4,800ft with no cracking or signs of instability. A steep, north test slopes produce the above-mentioned sluff. Below 5,200ft surfaces were moist at 3p.

A profile @ 6650ft, SE. Ridge between Lake Ann and Rainy Lake, location has minor to moderate previous wind loading
HS 240cm, HST 23cm
↓23cm- Tilt test produced easy, clean results at the 2/3 interface, though no planar results in other tests. Anticipated persistent grains, tho couldn't positively ID them at this interface.
↓39cm- Resistant planar, and non-propagating test results (CTM(RP), ECTN12) on rounding surface hoar (4.0-6.0mm, Jan 18th?).
↓44cm- thin MLK crust
↓68cm- The Jan 5th surface hoar (6.0mm, very rounded) and produced no test results including with deep tap test (DTTN). SH may be less problematic here than other locations, tho the trend is encouraging.
No other notable snow profile observations.

Problem	Location	Distribution	Sensitivity	Size	Comments
Dry Loose	N E S W	Isolated Specific Widespread	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Layer Depth/Date: 5-10cm
Wind Slab	N E S W	Isolated Specific Widespread	Unreactive Stubborn Reactive Touchy	D1 D1.5 D2 D2.5 D3 D3.5 D4 D4.5 D5	Comments: Had to look hard to find any wind-affected surfaces. Evidence of both east and west wind since Fri (2/3) night. Drifting is not significant where we traveled. Any recent slabs are buried under soft, unaffected snow.

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