Avalanche Forecast
Regions: Olympics.
A cold front will cross the Northwest on Friday morning. Wind and increasing rain and snow will cause an increase in the avalanche danger on Friday morning.
Detailed Forecast
A moderate cold front will approach from the west Thursday night and cross the Northwest on Friday morning. This will be accompanied by increasing winds, moderate rain or snow and slightly lowering snow levels. Showers following the front should decrease Friday afternoon. A convergence zone may enhance showers near Stevens Pass Friday afternoon.
New wind slab is likely on lee slopes. You should be most likely to trigger a wind slab on north to southeast aspects near and above treeline. Watch for signs of firmer wind transported snow or cracking snow.
New storm slab is also likely on sheltered slopes again mainly near and above treeline. This is most likely in any areas that receive an inch of snow or more an hour for at least a few hours.
It is now March and the sun is getting stronger. Watch for sun effects on new snow mainly on solar aspects but possibly aspects as well. Wet loose avalanches are becoming more likely if you see pinwheels or initial small natural wet loose releases.
In sheltered areas where the winds are not strong and the snowfall not heavy the increase in avalanche danger should be more limited. In such areas the cooling trend may also help create right side up layering with lower density snow near the surface.
Snowpack Discussion
Over the past month two major storm cycles moved across Northwest.
The first two week storm cycle ended 25 February and deposited about 9 feet mostly wet heavy snow at Hurricane and caused avalanches across the region.
The second week long storm cycle wound down last Sunday and produced similar water equivalents as the February cycle.  Water equivalents and snowfall for the the second cycle were about 4 inches and 2 feet at Hurricane. So this was a cycle of wet snow and rain. This produced avalanches again across the region including reports from Holden Village, Stevens Pass, Tumwater Canyon, Alpental and Snoqualmie with pass closures at times.
NWAC observers Tyler and Katie Reid last Friday at Hurricane reported wet and saturated upper snow pack layers and numerous wet loose avalanches to size 2. Warming effects had penetrated quite deeply into upper snowpack layers. Here is a video from Tyler and Katy at Hurricane on Friday.
Warm wet weather last weekend caused wet snow conditions and many wet loose avalanches at Hurricane with several cornice collapses as well as reported by NWAC observer Katy Reid on Sunday.
Cycles of daytime warming and night time cooling have generally been seen the past couple days. The upper snowpack has temporarily stabilized and no significant avalanches have been reported the past couple days in the Cascades. Rain crusts at or near the surface in many areas in the Cascades were generally firm and fairly thick Thursday morning and are only softening on Thursday afternoon. Similar conditions should be seen at Hurricane Ridge on Thursday.
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: 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: Likely
Expected Size: 1 - 1
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: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1