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Avalanche Forecast

Archived

Apr 8th, 2015–Apr 9th, 2015

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Snoqualmie Pass.

The main avalanche problem should be possible small loose wet avalanches on solar slopes. Use caution on slopes below cornices and on ridges where it can be hard to know if a cornice is present.

Detailed Forecast

The weak shortwave, moisture and instability should continue to linger over Washington on Thursday. So expect cumulus and a slight chance of showers will be forecast again Thursday afternoon mainly over the central and south Cascades on both sides of the crest. This weather will not greatly change snow conditions.

It's April, so be aware of the increased sun effects reaching more aspects and affecting the snow surface fairly quickly. Loose wet avalanches involving shallow amounts of recent storm snow will be possible Thursday, especially in any direct sun on solar slopes.  

Cornices won't be highlighted as an avalanche problem due to the cool weather but use caution on slopes below cornices and on ridges where it can be hard to know if a cornice is present.

Snowpack Discussion

A large weak upper trough moved over the Northwest last weekend through early this week. This caused some light snow at times west of the crest with low snow levels. Freezing levels have been very low in April compared to most of the winter, averaging about 4-5000 feet.

Backcountry reports from across the Cascades near and above treeline indicate cool, preserved snow on non-solar aspects with limited wind effects, gradual settlement and generally good bonds to the previous crust.  On solar aspects, sun breaks have caused only small loose wet avalanches and crusts.

Some large cornices continue to be reported along ridges especially in the north Cascades.

A weak shortwave, moisture and instability is causing cumulus and showers Wednesday mainly over the central and south Cascades on both sides of the crest.

Snowpack problems west of the crest should remain in the upper or surface layers. The mid and lower snowpack west of the crest consists of layers of stable consolidated rounded grains or melt forms and crusts from multiple warm periods this season. Many areas at lower elevations do not have enough snow to cause an avalanche danger.

Problems

Loose Wet

Loose Wet avalanches are the 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. 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.