Observation: NWAC Forecaster

All Observations

Basic Information

Observation Date:

December 15, 2022

Submitted:

December 15, 2022

Observer:

NWAC Forecaster - Joe Dellaporta

Zone or Region:

Mt Hood

Location:

North Side- Tilly Jane

Recent Avalanches?

None Observed

Cracking?

None Experienced

Collapsing?

None Experienced

The layer of buried surface hoar was easily identifiable along the Tilly Jane Ski Trail. Look for a thin gray line 30-50 cm below the snow surface.

SE aspect @ 5070 ft

4/5 test pits produced fully propagating results in extended column tests. All of which failed on the same layer of buried surface hoar (SH). Generally this SH was found below and near treeline in the Tilly Jane area.

ECTP14 30 cm down on 4mm SH.

Large grained surface hoar. The culprit of the propagating results.

ECTP 27 30 cm down on new/old snow interface. This layer was comprised of mixed forms (buried near-surface facets & decomposing grains) .

NE Aspect @ 6600 ft.

Some transport on the upper mountain. A sign that wind slabs may exist near-by.

Advanced Information

Cloud Cover:

Mostly Sunny

Temperature:

25°F

Wind:

Light , E

Today was a clear and calm day at mid and lower elevations. Once above treeline, moderate east winds were present and some snow transport was observed on the upper mountain.

Today I went out to investigate the distribution of 12/8 buried surface hoar on the north side of Mt Hood along the Tilly Jane Ski Trail. I dug several test pits on multiple aspects/elevations throughout the day as a way to see where this surface hoar lived. In some locations this weak layer was easily identifiable with the naked eye and appeared as a thin gray line in the upper snowpack. Other areas this buried weak layer was harder to find, but identifiable with snowpack tests. In 4 out of 5 test pits I received propagating results on this layer of buried surface hoar. Generally, this layer was found 12-15 inches below the snow surface and existed at lower and mid elevations. Once above treeline, this buried weak layer was harder to locate and snow surfaces were wind textured and firm.

Problem	Location	Distribution	Sensitivity	Size	Comments
Persistent 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	Layer Depth/Date: 30-40cm Weak Layer(s): Dec 8, 2022 (SH) Comments: Distribution is specific to areas below and near treeline, especially in areas with without canopy ( meadows, open slopes). Still reactive with propagating results in test profiles.

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