Avalanche Forecast
Issued: Apr 27th, 2018 11:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet.
NWAC,
Northwest Avalanche Center
The primary avalanche danger has shifted to lower elevations, mainly below treeline, where Loose Wet avalanches remain possible. Refreezing surface snow with little new snow will limit the avalanche danger at higher elevations.
Summary
Detailed Forecast
The avalanche danger is diminishing as temperatures cool and cloud cover increases. The main avalanche concern will shift to below treeline where you could still trigger Loose Wet avalanches on Saturday. If you sink in wet snow up to the top of your boots, avoid slopes over 35 degrees.
Cooling will allow for gradually refreezing surface snow near and above treeline. The newly forming crust will limit the possibility of avalanches. Only light amounts of new snow is expected in a showery weather pattern Saturday with generally light winds. There is not expected to be enough new snow or wind to create a significant avalanche problem in higher terrain.
If local areas are receiving greater than forecast new snow or rain, be prepared to change travel plans and avoid travel on or below steeper terrain.
Snowpack Discussion
Cooling and clouds arriving late Friday allowed for previous wet and weak surface snow to begin re-freezing and consolidating, especially near and above treeline.
Sunshine and increasingly warm temperatures Sunday through Friday over the Mt. Hood region have continued the transition to a fully spring-like snowpack of well drained large melt-freeze snow grains. Since late Monday morning, most mid-elevation sites have remained above freezing and by Thursday, daytime high temperatures were in the 50's and 60's at mid-elevation stations.
Significant snowfall accumulated in the Mt Hood area earlier in the week. Around 16-20 inches (40-50 cm) of snow fell 4/15 through 4/17. Strong west-southwest winds during the storm transported the new snow forming wind slabs which have subsequently healed.
While numerous layers can still be found within the snowpack, there are no significant layers of concern at this time.
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.
Elevations: Below Treeline.
Likelihood
Expected Size
Valid until: Apr 28th, 2018 11:00AM
