Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

March 23, 2023

Submitted:

March 23, 2023

Observer:

NWAC Forecaster - Joe Dellaporta

Zone or Region:

Mt Hood

Location:

Pea Gravel Ridge

Recent Avalanches?

None Observed

Cracking?

Widespread

Collapsing?

Isolated

Long shooting cracks @ treeline (6000 ft)

Advanced Information

Cloud Cover:

Overcast

Temperature:

Below freezing°F

Wind:

Moderate , W

New/Recent Snowfall:

HN: 5 cm

The start of the tour @0900 I observed filtering sunshine and fairly calm windspeeds. However, as the morning progressed the the clouds started to quickly thicken and the wind speeds notched up into the moderate range. Once at ridgetop, I observed heavy drifting and strong wind speeds out of the West. Snow intensity started picking up @ 1100. By the time I was wrapping up at noon it felt quite stormy.

I went out to investigate the distribution of graupel (that fell yesterday 3/22) and to check on the sensitivity/distribution of the wind slab problem.

First off, It wasn't hard to find the graupel in most places I traveled this morning. I found it sitting near the surface, just above the most recent stout crust. Travel in the BTL was quite rough and slick at times. As I climbed closer to ridgetop, winds picked up into the moderate range and I started to observe active drifting. It wasn't hard to find wind drifted snow on leeward features. On test slopes I found this wind drifted snow to be quite reactive. It was fairly easy to make these shallow slabs fail or see shooting cracks. At these elevations ( 5-6000ft), I found these slabs to be soft (4F) and shallow (<6in deep).

At treeline, conditions started to intensify. Winds ramped up into the strong range and heavy drifting resulted. Wind drifted snow started getting stiffer (1F) due to these higher wind speeds. Along the ridgeline, I started seeing notable long shooting cracks and small test slopes producing slightly deeper (6-12in) hard slabs. These obvious red flags kept me off of nearby steeper wind loaded terrain.

These wind drifted slabs were failing on a layer of graupel just above a stout crust that fell yesterday (3/23). Look at photos for more details.

Problem	Location	Distribution	Sensitivity	Size	Comments
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: Wind drifted slabs were quite reactive this AM. BTL/NTL these slabs were shallow and soft. Gaining elevation into the ATL higher wind speeds resulted in firmer (1F hard) wind slabs. Slabs were still fairly small and failing on a layer of graupel 6-12 in below the snow surface.

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