Windy Morning on Tumalo

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Wednesday, Mar 1, 2017 8:22 PM
Pro Ob
Three Sisters Area (44.004208, -121.640625)
Ob Date/Time:
Wed, Mar 1, 2017 - 7:36 PM
Report Type:
Snow Conditions
Mode of Travel:
Ski or Snowboard

Written Report:
It was a beautiful morning on Tumalo; starting out with a cold cloud over the butte but quickly clearing and warming. There was evidence of previously strong winds from the West and I was impressed to find evidence of blowing snow even well below treeline in smaller open glades. When I was on the summit the wind was Moderate from the west, but it seemed like it had moved most of the snow it was going to and there wasn't active loading into the bowl. Below the bowl was a whole other story with mostly moderate snow transport from variable directions wrapping around the butte. Picture 1 is of the snow surface below the bowl (@ treeline) and picture 2 is of the usual skin track up the North side of the bowl.

Notably I did not find a widespread wind slab avalanche problem on Tumalo. The wind had packed the snow into a cohesive slab, but there didn't appear to be a significant weak layer beneath. I did a few compression tests on a wind loaded slope at treeline and found a few resistant planar fractures and mostly breaks in this wind deposited snow. The one exception to this was a very hard and shallow (4 inches) wind slab at the very upper reaches of Tumalo Bowl (it disappeared and the snow softened up a bit even before I made my first turn).

I also dug lower in the terrain in a sheltered west facing glade and found a slight weakness down 23 cm. in the storm snow, but no persistent weak layers.

My test results and weather obs. are listed below:
7:10, 6580 ft. West
Scattered clouds, NO precipitation
Temperature -7 C
Wind was Light and there was evidence of previous Light Blowing Snow
Surface form/size: Wind broken and rimed Precipitation Particles 2mm, Height of Snow 3m, Boot Penetration 75 cm, Ski Pen. 25 cm.
Shovel Tilt Result down 23 cm. in 3mm stellars
CTE PC down 23 cm.
CT M RP down 23 cm.

Roller North-East of Tumalo Bowl, 9:15, 7320 ft. East
Scattered High Clouds
Temperature -4 C
CTM BRK down 30 cm. CTH BRK down 58 cm.
CTM BRK down 30 cm. CTH RP down 58 cm.


Caption: wind transport at treeline

Caption: scoured NE ridge