Avalanche Forecast
Regions: Olympics.
A mix of winter like and spring conditions and concerns should be seen on Wednesday.
Detailed Forecast
Clouds should decrease near and west of the crest Wednesday morning. Partly or mostly sunny weather should be seen Wednesday afternoon with moderate temperatures and generally light west winds.
The dry weather and moderate temperatures should lower the avalanche danger a notch on Wednesday compared to the past few days.
But the sun is getting stronger and stronger now that we are well into April. The most extensive concern should be possible wet snow avalanches by Wednesday afternoon especially in new snow on solar slopes above treeline but in older wet snow on other slopes as well. Watch for wet surface snow deeper than a few inches, roller balls in surface snow and small natural wet loose releases that usually precede more major wet loose snow avalanches. Avoid terrain traps where a small but powerful wet loose avalanche could have unintended consequences.Â
A less extensive second concern will be possible new wind slab from in the above treeline zone. This should be mainly in the higher parts of the Olympics above Hurricane. This will be limited to lee slopes above treeline that get a few inches of snow. Watch for small areas of firmer wind transported snow.
New storm slab seems unlikely due to the cooling trend and limited amounts of new snow. This should be also be mainly in the higher parts of the Olympics above Hurricane. But watch for small areas of short lived storm slab in more sheltered areas above treeline that get a few inches of snow.
Although it will not be listed as a primary concern continue to be wary of cornices. Cornice failures are often seen during the transition to spring weather. Cornices have grown large recently and often break back further from the edge than expected.
Snowpack Discussion
A front crossed the Northwest Friday. Another moist front crossed the Northwest Saturday afternoon and night. Water equivalents and snowfall for these systems at Hurricane were in the .7 and 5 inch range respectively. Warmer temperatures were seen by Sunday and especially Monday. The recent snow and warmer temperatures caused avalanches. Some avalanches were triggered by cornice failures.
NWAC observer Katy Reid observed mashed potato snow, natural pinwheeling and increasing ski penetration into wet surface snow Sunday afternoon. She reported shallow wet loose avalanches below treeline, but found one larger (D2) wet loose avalanche on a steeper NE aspect below treeline (see picture below).  Digging around on different aspects near and below treeline, she found the saturated upper snow (15-50 cm) overlying a hard melt-freeze crust to be un-reactive in snowpit tests. No reports were available Monday, but warmer temperatures and sunshine likely led to additional wet snow avalanches. Cornices have grown large over the last few weeks.
Wet loose avalanche near Maggie's Bowl, Hurricane Ridge, by NWAC observer Katy Reid on Sunday.
Less avalanche activity should be seen by Tuesday as a front approaches the Northwest and clouds cut down on solar effects and temperatures begin to cool. The southwest to northeast oriented front should shift from the Olympics and north Cascades this afternoon to the south Cascades Tuesday evening. Up to a few inches of snow is possible in the above treeline zone this afternoon through tonight.
Avalanche Problems
Loose Wet
Release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. They generally move slowly, but can contain enough mass to cause significant damage to trees, cars or buildings. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
Travel when the snow surface is colder and stronger. Plan your trips to avoid crossing on or under very steep slopes in the afternoon. Move to colder, shadier slopes once the snow surface turns slushly. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches.
Several loose wet avalanches, and lots of pinwheels and roller balls.
Loose wet avalanches occur where water is running through the snowpack, and release at or below the trigger point. Avoid terrain traps such as cliffs, gullies, or tree wells. Exit avalanche terrain when you see pinwheels, roller balls, a slushy surface, or during rain-on-snow events.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1
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.
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: Alpine.
Likelihood: Unlikely
Expected Size: 1 - 1