Avalanche Forecast
Issued: Feb 16th, 2015 10:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet.
NWAC,
Northwest Avalanche Center
Look for increasing warmth and sunshine on Tuesday to potentially activate wet loose avalanches during the afternoon hours especially on steeper solar slopes.
Summary
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.
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.
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 a mix of rain and wet snow along the east slopes. Since then, a benign weather pattern with mild temperatures has set in. Sites in the northeast Cascades that received the most snow during the last storm cycle, such as Washington and Harts Pass, have seen over a foot of settlement over the last week.
NWAC pro-observer Jeff Ward has been at Hart's Pass the past couple days and reports overnight refreezing of surface snow followed by small ski triggered loose wet avalanches on solar slopes.
NWAC pro-observer Tom Curtis was on Labyrinth Mountain up the Little Wenatchee drainage on Saturday and found a no signs of instability and little snow on south slopes below 5000 feet.
While the January 15th facet/crust interface can still be identified in parts of the NE Cascades, this PWL has been stabilizing and become unlikely to trigger. As a result the Persistent Slab problem has been removed from the NE Cascade forecast.
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
Expected Size
Valid until: Feb 17th, 2015 10:00AM
