Avalanche Forecast
Regions: Olympics.
Previous wind slab is the most likely problem on Wednesday. Evaluate the snowpack carefully and identify terrain features of concern such as convex rollovers and slopes that may have received recent wind deposited snow.
Detailed Forecast
Light snow showers should end at Hurricane by Wednesday morning. A short relative break may be seen at Hurricane Wednesday afternoon.
New wind slab is unlikely due to limited amounts of new snow at Hurricane. Older wind slab is most likely on lee north to southeast slopes near and above treeline.
New storm slab is also unlikely due to limited amounts of new snow at Hurricane. But watch for small areas of shallow wind slab if you find there has been more than a few inches of new snowfall.
Also here is a heads up that a strong wet warm front is headed our way for Thursday.
Snowpack Discussion
Deep storm snow that fell during mid-late December is well settled, homogeneous and has stabilized so the current avalanche danger should be confined to the uppermost recent storm snow.
The latest period of snowfall should have deposited about 1.5 feet of snow at Hurricane from about Friday to Sunday with fluctuating snow levels and periods of strong, mostly S-SW winds.
A fairly vigorous surface low pressure and frontal system will cross the south Cascades Tuesday and Tuesday night. This should bring heavy snow to the south Washington Cascades, moderate snow to the central Cascades and lighter amounts of snow to the Olympics and north Cascades. A minor drop in snow levels should be seen following this system except for a bump in snow levels in the passes when winds change to west there Tuesday night.
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, South East.
Elevations: Alpine, Treeline.
Likelihood: Possible
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: All elevations.
Likelihood: Possible
Expected Size: 1 - 1