Avalanche Forecast
Issued: Jan 20th, 2020 10:00AM
The alpine rating is Storm Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeFreezing levels begin to lower and there is a return to precipitation Tuesday, with the volcanoes getting the highest water amounts. Areas of the zone that receive less water may have locally lower avalanche danger, but danger should be increasing throughout the day in all locations. Avoid being on or under avalanche terrain if you see obvious signs of instability such as recent avalanches, whumpfing, or shooting cracks.
Summary
Snowpack Discussion
New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.
Problems
Storm Slabs
Storm slabs should develop at all elevations Tuesday as snow levels lower and precipitation falls on the surface crust created over the weekend. Thicker and more reactive slabs may develop on leeward slopes due to wind transport. Use small test slopes and hand-pits to investigate the bond between the new snow and the existing surface. Two pulses of precipitation should affect the zone, with a brief break between them, meaning that mid-storm layers will also need to be investigated. If you find a poor bond and more than 6 inches of cohesive snow, avoid slopes greater than 35 degrees. At lower elevations, heavy snow may exist, with avalanches possibly more wet loose in nature.
Release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm-slab problems typically last between a few hours and few days. Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
Storm slabs usually stabilize within a few days, and release at or below the trigger point. They exist throughout the terrain, and can be avoided by waiting for the storm snow to stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 21st, 2020 10:00AM