Observation: Snowbasin Backcountry

Observation Date
01/21/2017
Observer Name
Bill Hunt

Region:

Location Name or Route
Snowbasin backcountry
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
West
Wind Speed
Moderate
Weather Comments
Wind picked up later in the day.
Snow Characteristics
New Snow Depth
14"
New Snow Density
Low
Snow Surface Conditions
Powder
Red Flags
Red Flags
Heavy Snowfall
Wind Loading
Cracking
Red Flags Comments
Today's forecast was spot on, with very sensitive soft wind slabs that were easy to trigger, from 9300' down to 7900'. Snow continued till 4PM.
Avalanche Problem #1
Type
Wind Slab
Trend
Same
Problem #1 Comments
Virtually all test slopes and ridgelines that we cut today produced soft slabs from 4 to 14" in depth, with sympathetic releases seen a couple times, up to 30 yards away.
Avalanche Problem #2
Type
Loose Dry Snow
Trend
Same
Problem #2 Comments
Some long running sluffs were seen, running up a couple hundred feet, even at relatively low elevations like 7500'.
Comments
4 to 6" soft wind slab at 9300'. Next, 8 to 10" soft wind slab was easily triggered along this ridge at 8500'. I was surprised to see slopes measured in the 35 degree range cracking and moving, although not moving far.
Here a cut on the lower angle side of this test slope, photo left, sympathetic'ed a couple yards over to the steeper section and produced a 6" soft slab about 10 feet wide. This propagated in width and depth somewhat, and ran about 100 yards.
Cracking was evident on many slopes that were not steep enough to move. Next, later in the day, this ridge area had loaded enough to have crowns in the 12 to 14" range; only moving about 15 yards because the slope angles go to the 30 degree range here fairly quickly, but anything with more sustained steepness and wind exposure could produce significant slides. I would call it Considerable above 8500', especially anywhere wind affected. Below 8500', it seems like a tricky Moderate hazard.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Snow Profile Coordinates