Avalanche Forecast
Issued: Mar 19th, 2015 9:04AM
The alpine rating is Storm Slabs and Loose Wet.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Good
Weather Forecast
A series of pacific frontal systems will bring waves of precipitation to the Interior Ranges. Friday will see overcast skies, precipitation amounts 5-15 mm, ridgetop winds moderate from the SW and freezing levels 1800-2000 m. Continued precipitation on Saturday with amounts up to 15 mm , ridgetop winds light-moderate from the SW and freezing levels near 1900 m. Later Saturday the front will move east setting up for a clearer, drying trend Sunday. Freezing levels will initially drop to valley bottom overnight Saturday then rise steadily during the day with treeline temperatures near 0 degrees. The way this system is tracking, southern parts of this region will likely see less precip amounts then what's posted above.
Avalanche Summary
On Wednesday, several natural slab avalanches and skier triggered avalanches up to size 2 were reported. Most of these avalanches failed on north- easterly aspects above 2000 m. With forecast snow, rain and wind, widespread natural avalanche activity is expected through the weekend.
Snowpack Summary
At higher elevations, up to 20-50 cm of snow sits over a plethora of old surfaces including wind affected surfaces, and/or old wind slabs and crusts which were buried mid-March. Previous strong winds have redistributed new snow into wind slabs on leeward terrain features and lower elevations (below 2000 m) are sporting spring-like, melt-freeze conditions. Digging deeper (40-70 cm below the surface) sits the mid-February facet/ crust interface. This interface has not been as reactive in the South unlike regions to the North. However, it is alive and well in test profiles. It may just require additional load and/ or a change in slab properties before it reaches threshold and becomes reactive. The late-Jan crust/surface hoar layer (around 1m deep) and the mid-January surface hoar (around 1.5m deep) have been dormant for several weeks.
Problems
Storm Slabs
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 20th, 2015 2:00PM