Avalanche Forecast
Regions: Cascades - West.
Look for increasing warmth and sunshine on Tuesday to potentially activate wet loose avalanches during the afternoon hours especially on steeper solar slopes.
Detailed Forecast
An amplified upper level ridge over the US and BC coast will dominate the weather once more day on Tuesday and maintain the dry and mostly clear conditions.Â
Freezing levels will rise and cool east winds will diminish on Tuesday afternoon, increasing the potential for generally small loose wet avalanches. Overnight cooling and surface refreezing will limit this problem during the night and morning hours, however warmer temperatures may activate small wet loose higher into the above treeline zone versus what was observed over the long weekend.
Watch for initial rollerballs or surface wet snow deeper than a few inches and be wary of the small wet loose avalanche potential especially near terrain traps. Small loose wet avalanches are most likely on steeper solar aspects near and above treeline. Â
As a result of the overall low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation.
Snowpack Discussion
Warm and wet southwest flow directed a series of fronts across the Northwest from about February 5th-10th, producing impressive rainfall totals but unfortunately causing more melt at lower elevations, making many slopes below treeline nearly snow free regardless of aspect. Generally 6-12 inches of wet snow fell at the tail end of the storm cycle last week near and above treeline. Since then, a benign weather pattern with mild temperatures has set in.
On Sunday, the snow surface was reported as generally firm and supportable following a clear night, softening the most on solar aspects during the afternoon. Pro-observer Dallas Glass was at Paradise over the weekend and observed some rollerballs and a couple small loose wet avalanches. Cool east winds likely dampened wet loose potential on Monday despite high freezing levels and mostly sunny skies.Â
Small wet loose avalanches were most likely to be triggered on steeper solar slopes especially below exposed rocks.Â
Rollerballs and small wet loose, SE aspect, above Van Trump park, MRNP, 2-15-15, photo by DDAmico
The mid and lower snowpack west of the crest should consist of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this winter.
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: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1