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RegisterJan 18th, 2018–Jan 19th, 2018
Olympics.
Wind and storm slabs should continue to thicken during heavy shower bands. Avoid travel on steep wind exposed terrain where fresh wind slab deposits are likely sensitive to human triggering Friday. Watch for building storm slabs during periods of heavy snow showers. Expect dangerous avalanche conditions at mid and upper elevations. Choose conservative terrain and avoid slopes exposed to wind affected snow.
Cool showery weather should persist Thursday night and Friday. Ridge crest winds should be moderate and diminishing gradually Friday. However winds and new snow will still be expected to be transported on exposed terrain.
Watch for changes in snow conditions, particularly stiffer more dense snow, likely a wind or storm slab. Avoid travel on slopes if you encounter wind stiffened surface snow, especially on steeper exposed terrain and steep roll-overs.
The temperature trend should continue to cool which will help deposit lower density new snow on top, which is where you want it, but in wind sheltered terrain.
Wind slabs near and above treeline remain the primary avalanche problem in this area, so remain conservative in your terrain choices especially as you venture into exposed terrain.
The best and safest snow will remain in sheltered terrain away from ridges.
A strong storm Wednesday through Thursday deposited storm snow of 8-10 inches by Thursday afternoon. The new snow fell at cooling temperatures causing a favorable density profile with colder looser snow over denser warmer snow.
However, strong winds Wednesday night through Thursday actively transported snow and built slab layers. These slabs became sensitive to human triggering on exposed steep terrain by Thursday afternoon, especially on NE-E facing slopes that were being loaded by wind deposited snow.
The new snow is bonding well to the old wet snow from rain or melting during last weekends sunny very warm weather.
The older snow is well settled and strong with various melt-freeze and rain crust layers throughout.
The height of snow across the terrain is quite variable with little snow in many areas below treeline. Numerous obstacles still exist at all elevations.
Observations
NWAC observer Matt Schonwald traveled in the Hurricane Ridge terrain Thursday, Jan 18. Matt found excellent right side up fresh snow of about 8 inches by Thursday afternoon that was bonding well to the underlying old wet snow and unreactive to human triggering in wind sheltered terrain.
In wind exposed terrain however, winds Thursday were actively transporting new snow and building sensitive slab layers. These reactive wind slabs were found mostly on NE-E facing terrain, mostly in the 6-8 inch range. Slabs were most sensitive in the mid-slope terrain and on steep wind rolls.