Avalanche Forecast

Issued: Mar 5th, 2015 10:00AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Loose Wet.

Northwest Avalanche Center NWAC, Northwest Avalanche Center

It is getting to be the time of year when you often need to watch for both winter and spring types of avalanche conditions. It is always good to read the forecast for details.

Summary

Detailed Forecast

Light winds and diminishing high clouds with sunshine and mild daytime temperatures are expected Friday. 

Most areas do not have sufficient surface snow to become wet and easily available for wet snow avalanches, however, sunshine and warm afternoon temperatures should maintain somewhat of a loose wet avalanche problem on Friday. Watch for wet snow deeper than a few inches or rollerballs or pinwheels on steep solar slopes. The problem of loose wet avalanches should not be extensive, but limit your terrain choices if you see more activity than expected.

Cornices will not be listed as a problem yet, but start to practice checking the ridges for these as we shift into spring.

Due to the low snowpack, especially below treeline, watch for terrain hazards such as open creeks, partially covered rocks and vegetation. Many areas below treeline do not have enough snow (new or existing) to pose an avalanche hazard.

Snowpack Discussion

The North Cascades Mountain Guides in the Washington Pass area reported a well bonded dense snowpack on February 22nd. No results from tests and rounding grains were seen at the January 15th facet/crust layers.

NWAC pro-observer Tom Curtis was at the north end of the Chiwaukums on February 25th and found minor new snow on a hard thick crust, no avalanche problems and a low avalanche danger in all the elevation bands. 

The latest report was from Tom Curtis, Wednesday, March 4th at Jove Peak in the Cascade-east-central zone, where a strong well drained snowpack was found. Very little soft surface snow was seen, with a strong, well bonded slab to 55 cm then the mid-January weak layer and below that another very strong, well bonded snowpack to the ground with about 120 cm total snowdepth at this location at 5500 ft on a SE aspect. The mid-January layer was not a concern presently as the overlying snow was so very strong and tests did not produce concerns.   

The latest snowfall in the Cascades was late last week when up to about 7 inches of snow fell east of the crest.

The Minor cooler weather on Sunday and Monday has been followed by sunny and gradually weather on Tuesday through Thursday. This should have stabilized any recent wind slab layers.

The persistent weak January 15th facet/crust layers can still be identified in parts of the NE Cascades, but have been stabilized and have become unlikely to trigger. As a result the Persistent Slab problem has been removed from the northeast zone.

Problems

Loose Wet

An icon showing 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: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

1 - 1

Valid until: Mar 6th, 2015 10:00AM