Aspect: All aspects and elevations

Bottom Line: Very heavy snowfall rates are expected today, with accumulations approaching 24″ by tonight. NW winds will be whipping around the new snow, and temperatures will be warming up drastically. All the red flags are present for a large natural avalanche cycle over the next day or two.

Travel Advice: Avoid all avalanche terrain! If you head out, stick to the trees and watch out for terrain traps where even small slides could pile up to be quite deep. Stay out of avalanche runout zones along valley bottoms. 

Avalanches will be likely within the new snow, and failing on the new/old snow interface. Wind loaded areas could accumulate enough critical loading to trigger deep persistent weak layers, which could cause wide propagation and very large avalanches that run full-path.

Aspect: All aspects, most likely on wind loaded aspects and features SW-S-SE-E.

Elevation: All elevations.

Travel advice: Consider any possible slopes harboring surface hoar as guilty until proven innocent. Always use safe travel techniques such as only exposing one person at a time both on the way up and down. Identify and avoid thin areas where weak layers are more likely to trigger a slide from. Group up in safe zones that are out of harms way. Have good communication, including radios and a set plan in case of an emergency. Be practiced at companion rescue.

• On wind-protected slopes, there is preserved buried surface hoar about 5-10″ deep
• Snow and wind events in December created layers of slab and weak, facetted snow
• Cold temperatures Dec. 3-5th created weak snow at the surface that is now buried in many places
• Over a meter deep: old weak layers are buried and difficult to trigger, but still there.
• Toward the very bottom: early season snowfalls and crusts linger and are very difficult to trigger but are still of concern for step-down potential.

5-10mm surface hoar observed Dec. 18/ Test pit from Jan. 1st with buried crust 70cm down