Observations from the northwest face of Gray Butte

Snowy conditions with poor visibility were experienced throughout the outing. Wind remained light out of the south. Observed snow level was around 4,800 feet. As of 12pm, the average new snow accumulation is about five to six inches. Some leeward areas held closer to 10 inches. 

As suspected, the new snow is laying on top of the old solar crust on all observed terrain. The thickness and supportability of the crust varies depending on aspect. Solar aspects hold a far thicker punchable crust, while northerly terrain has a very thin and sometimes unnoticeable crust.

There were a few signs of instability on northerly terrain. The most obvious were the easily triggered dry-loose avalanches due to ski cuts. These dry-loose avalanches could entrain moderate amounts of snow and run up to 100 feet. Some cracking and slab characteristics were also observed on steeper convexities under skis. 

Two pits were dug today. Both were at 7,900 feet at opposite sides of a ridgeline. 

• The first pit was on a northwest aspect. As mentioned, five inches of new snow was found sitting on top of the old surface crust. On compression tests, failure occurred on tap 12 with a sudden collapse at the new snow - old crust interface (down 14cm). This result was replicated two more times.
• The second pit was on a southeast aspect. This held a far thicker crust (6cm) and more new snow (17cm) compared to pit #1. Upon compression test, failure occurred on isolation just below the old crust. On ECT, failure also occurred on isolation.

• Observation Location: Northwest face of Gray Butte
• Elevation: 7,900 feet
• Date: 20230319
• Time: 1200
• Observer: S. Clairmont and E. Falconer
• Sky Conditions: Obscured (X)
• Current Precipitation: Type - SN, Rate - S-1
• Air Temperature: 25 °F
• Total Snow Depth (HS): 194 in (493 cm)
• 24-hour New Snow Depth (HN24): 4 in (10 cm)
• Wind Direction: S
• Wind Speed: Light (L), 1-16 mi/hr, twigs in motion
• Column & Block Tests:
  • Slope Angle & Aspect 30º, NW
  • CT12 [SP] ↓ 5 in (14 cm)

Observations from the north face of Black Butte

Elevation ranged from 4,000 to 5,600 feet. Overcast skies and warm air remained over the area throughout the outing. Winds remained calm to light of the southwest. At ridge tops, wind picked up to moderate. Wind transport was not observed, likely due to the heavy snow and prevalent surface crust.

Soft, heavy snow can still be found in the most shaded of areas. A thin solar crust was found on majority of the observed terrain. With new snow in the forecast tonight and tomorrow, it's safe to assume this snow will lay on this relatively firm crust. 

Signs of wet instabilities were abundant in the form of large roller balls, pinwheels, and old wet-loose avalanches. These avalanches entrained snow down to the rocks, leaving gouge marks across the slopes and debris blocks the size of microwaves. On the ski down, a ski cut triggered a 10-foot wide wet-loose avalanche that traveled 40 feet into trees. This was a great reminder that, although the current temps are not the warmest we have seen this week, wet instabilities still exist when the upper snowpack is heavily saturated and temps are above freezing.

 

• Observation Location: North face of Black Butte
• Elevation: 5,600 feet
• Date: 20230318
• Time: 1300
• Observer: S. Clairmont
• Sky Conditions: Overcast (OVC)
• Current Precipitation: Type - NO
• Air Temperature: 39 °F
• 24-hour New Snow Depth (HN24): 0 in (0 cm)
• Wind Direction: SW
• Wind Speed: Light ((L), 1-16 mi/hr) to Moderate ((M) 17-25 mi/hr)