Avalanche Forecast
Regions: Olympics.
Very strong winds and snow showers should combine to form new wind slabs on lee slopes, especially NW-NE facing. Watch for earlier storm slabs that may be masked by shallow colder surface snow. Dangerous avalanche conditions are expected near and above treeline Thursday.
Detailed Forecast
Yet another atmospheric river is slamming the Olympics Wednesday, bringing stormy wet weather with rising snow levels through Wednesday night.
The heavy precipitation at rising freezing levels should produce one or more natural avalanche cycles during the warmest periods, mainly Wednesday night.Â
By Thursday morning, cooling and light to moderate showers with continued very strong winds are expected.Â
The cooling should help wet snow to begin consolidating and cause a lowering danger during the day with shallow new snow accumulations expected.Â
However, near and above treeline, very strong winds should build new areas of wind slab on a variety of aspects, but mainly on NW-NE facing slopes below ridges.Â
Be especially aware that new shallow lower density snow may mask earlier storm slab formations, especially on slopes that did not avalanche overnight Wednesday.Â
Snowpack Discussion
Weather and Snowpack
Last week was wet and relatively mild with a series of active fronts transiting the region resulting in fluctuating freezing levels and periods of very strong winds.
A front Sunday brought about a foot of snow to Hurricane by Monday morning. No new snow was reported Tuesday morning.
A strong storm arrived midday Wednesday bringing heavy snowfall at rising temperatures and very strong south ridgetop winds.Â
The mid and lower snow pack in the Olympics should generally be a stable mix of crusts and layers of moist and rounded snow crystals.
Recent Observations
The ranger at Hurricane reported a foot of new snow on Monday morning with snow sliding off the road cuts and onto the road in many places. The Sunrise path on a northeast slope about a 1/2 mile from the visitor center released an avalanche that entrained snow to about 1' and became 100 feet wide although it could not be determined if it was a loose or slab avalanches due to low visibility.
On Tuesday the ranger added that there had been many 6-12 inch storm slab avalanches on Monday.
No observations from Wednesday, March 9.
Hurricane Weather Station
Internet communications to the station have been disrupted but will hopefully be restored soon. We are actively working on the solution.
Avalanche Problems
Wind Slabs
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.
Wind Slabs form in specific areas, and are confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas..
Wind Slab avalanche. Winds blew from left to right. The area above the ridge has been scoured, and the snow drifted into a wind slab on the slope below.
Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1
Storm Slabs
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: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1