Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Dec 4th, 2016–Dec 5th, 2016

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Olympics.

Despite a favorable cooling trend with Saturday night's storm, westerly winds will build shallow wind slab on lee aspects. Look for wind slab development further downslope than you might expect due to locally strong winds and persistent loading. 

Detailed Forecast

A strong frontal system will quickly sweep through the Olympics Saturday night. This system should deliver around 6 inches of snow to Hurricane Ridge. A cooling trend beginning Saturday night will continue through Sunday as shower activity quickly wanes later Sunday morning. 

Despite a favorable cooling trend with this storm, westerly winds will build shallow wind slab on lee aspects near and above treeline. Look for wind slab development further downslope than you might expect due to locally strong winds and persistent loading. Watch for firm wind transported or hollow sounding snow. 

Avoid ridges that have a cornice and slopes below cornices.

In most of the lower part of the below treeline band there is still insufficient snow for avalanches but watch for early season hazards such as terrain traps, rocks and creeks.

Snowpack Discussion

Weather and Snowpack

A front crossed the Olympics Friday with an inch of new snow reported by NPS rangers at Hurricane Ridge through Saturday morning. Post-frontal showers were generally light to moderate on Saturday and ridgetop winds were moderate out of the south. With the mild snow levels seen so far this season, most avalanche problems have been confined to the most recent storm layers found in the upper snowpack.  

Recent Observations

NWAC pro observer Matt Schonwald visited Hurricane on Thursday and reported widespread wind effects but a generally well bonded snowpack and snow profiles in pits that lacked a slab structure. The snow was found to be unconsolidated at lower elevations making terrain traps and creek crossings a hazard.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.