Avalanche Forecast

Issued: Mar 7th, 2015 10:00AM

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

Northwest Avalanche Center NWAC, Northwest Avalanche Center

Watch for wet surface snow on steep solar slopes that could lead to loose wet avalanches and potentially weakening cornices.

Summary

Detailed Forecast

Light winds, mostly sunny weather and mild daytime temperatures are expected again Sunday. This should not bring much change to snow conditions along the east slopes.

Most areas do not have sufficient loose surface snow to become wet and easily available for wet snow avalanches. But sunshine and warm afternoon temperatures will thaw and melt some snow Sunday midday and afternoon. 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 are not listed as an expected problem, but may begin to weaken during the warmest part of the day so it's time to be practicing checking the ridges 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 last snowfall in the Cascades is becoming a fading memory and was near the end of February when about 7 inches of snow fell east of the crest.

This was followed by local strong northeast winds in the Cascades at the end of February. Local wind slab formed perhaps mainly along the west slopes.

Sunny and gradually warmer weather has been seen the first week of March. This will have stabilized wind slab from the end of February and further consolidated the snowpack. Recent reports throughout the Cascades generally indicate hard or firm or stable old snow. There was almost no snowfall in January and February and none so far in March. The snowpack at lower elevations is meager to non-existent and way below normal. There have not been any reports of significant avalanches for a long time. Some folks are finding a bit of cool old snow surviving on some north to east slopes at high elevations.

NWAC pro-oberserver Tom Curtis was at Jove Peak last Wednesday in the central east zone and found a strong well drained snowpack. A pit had 55 cm of strong, well bonded snow over the old mid-January facet/crust layers over rounding grains. There was about 120 cm total snow at his location at 5500 ft on a SE aspect. The mid-January layer was not a problem due the strong overlying snow and a lack of CT or ECT results.

The North Cascade Mountain Guides at Harts Pass yesterday reported some cool snow on north to east slopes with numerous test giving no results and no avalanches.

Here is a photo showing some varied surface snow conditions from near Silver Star Peak yesterday by NWAC forecaster Dennis D'Amico.

Although the persistent January 15th facet/crust layers can still be identified in parts of the NE Cascades, they should be 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

Possible

Expected Size

1 - 1

Valid until: Mar 8th, 2015 11:00AM