Avalanche Forecast
Issued: Jan 31st, 2018 3:58PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeThe incoming weather will give little time for storm slabs to heal. Stick to supported slopes and watch for signs of unstable snow such as whumpfs and cracks.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
THURSDAY: Flurries with 5 cm accumulations / moderate southwest wind / alpine temperatures around -6 C.FRIDAY: 10-20 cm of snow / moderate to strong southwest wind / alpine temperatures around -3 C.SATURDAY: 15-30 cm of snow / moderate to strong west wind / alpine temperatures around -1 C.
Avalanche Summary
Preliminary reports of a few large avalanches suggest a widespread natural avalanche cycle occurred during Tuesday's storm.The most recent report of a persistent slab avalanche was on Saturday, when a size 2 avalanche on a buried surface hoar layer was remotely triggered on a northeast aspect in the alpine. Tuesday's storm would have tested the various persistent weak layers in the region, but at the moment we don't have enough observations to know whether or not they layers were reactive during the storm.
Snowpack Summary
Westerly winds and ongoing flurries are likely building fresh wind slabs in exposed terrain. This sits above 50 cm of settling snow from Tuesday's storm, which is likely still reactive to human triggers.A weak layer buried in mid-January remains a concern and is now 60-100 cm deep. In most areas this layer is a crust, but it may also be surface hoar in sheltered areas at treeline and below. Prior to the storm, this layer produced sudden snowpack test results in the Shames area and avalanche activity at upper treeline and alpine elevations. Professionals have also been monitoring another two crust / surface hoar layer that were buried in mid-December and early January that are now 100-150 cm deep. These layers were most recently active in northern parts of the region near Bear Pass.
Problems
Storm Slabs
50 cm of recent snow has formed fresh storm slabs. Slabs will be most reactive in wind-affected terrain at higher elevations.
Minimize exposure during periods of heavy loading from new snow and wind.Be cautious as you transition into wind affected terrain.Choose well supported terrain without convexities.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Several weak layers in the upper snowpack have the potential to produce large avalanches. Sheltered treeline areas with preserved surface hoar are the most suspect for human triggering.
Watch for signs of instability such as whumpfing, or cracking. Avoid shallow, or thick to thin snowpack areas where triggering a deeper layer is more likely.Be cautious on convex rolls at treeline where buried surface hoar may be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 1st, 2018 2:00PM