Avalanche Forecast
Issued: Jan 18th, 2018 4:40PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
High -
Weather Forecast
TONIGHT: Flurries. Accumulation 2-5 cm. Ridge wind moderate, southwest. Temperature -6. Freezing level 800 m.FRIDAY: Cloudy, flurries. Accumulation 1-4 cm. Ridge wind light, southwest. Temperature -4. Freezing level 1000 m.SATURDAY: Cloudy, flurries. Accumulation 2-5. Ridge wind light, southwest. Temperature -6. Freezing level 1000 m.SUNDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind strong, south. Temperature -5. Freezing level 1100 m.
Avalanche Summary
On Thursday explosive control work produced numerous size 1.5-2 storm slab avalanches as well as a size 2.5 and a size 3 that stepped down to the mid-December layer on north to northwest aspects above 2000 m. Ski cutting also produced numerous size 1-1.5 on southerly aspects from 1500-1900 m.Wednesday there were reports of a skier accidentally triggering a size 1 wind slab on an east aspect at 2000 m that is suspected to have failed on the most recent January 16th surface hoar layer, as well as a very large whumpf on a northeast aspect at 1800 m that is believed to have been associated with the mid-December layer.On Monday there were reports of two skier accidentals triggered on a northwest aspect between 1980-2000 m. The first was a size 1.5 and the second, triggered about thirty minutes later, was a size 2. A natural size 2 loose wet avalanche was also report on a southwest aspect at 2100m, as well as numerous explosive triggered size 2-3.5 slab avalanches running on weak layers deep in the snowpack.
Snowpack Summary
The snowpack is complex with several buried weak layers of concern that remain active and have produced several recent, large and destructive avalanches.Below 1900 m Wednesday night's rain has formed a thin crust on all aspects. At higher elevations, 10-25 cm of new snow now covers the January 16th surface hoar/ crust layer. This crust can be found on solar aspects while surface hoar has been buried on shaded aspects above 1600m. Below the January 16th crust lies the January 5th interface which also consists of a crust/surface combination and is buried 50-80 cm below the surface. The late-December surface hoar layer is buried 80-100 cm below the surface, and the spooky mid-December surface hoar layer is now 100-140 cm below the surface. This spooky interface continues to produce sudden snowpack test results and is most pronounced at treeline, but is also present below treeline. Two laminated crusts created by rain events in late November lay just below the mid-December interface, and may co-exist with facets. In shallow, rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 19th, 2018 2:00PM