Avalanche Forecast

A very weak trough should move across the area on Saturday, with the main effect a slight cooling and introducing some clouds mainly in the Northwest Cascades. There is a slight chance of a few showers in the Northwest Cascades but any precipitation there would be brief and light. Sunnier conditions should be seen in the southwest Cascades, Mt Hood and east of the crest.

The avalanche danger should decrease a bit on Saturday due to some clouds and slightly cooler temperatures compared to the past few days of hot weather. But wet snow conditions should still prevail on Saturday and the regional focus will continue on possible loose wet avalanches, cornice failures and glide avalanches.

Loose wet avalanches should still be possible on Saturday. Melt-freeze crusts can quickly break down in spring sunshine. In areas that have received more recent snowfall, small loose wet avalanches have the potential to entrain deeper layers. Be aware of terrain traps where even a small loose wet avalanche could have unintended consequences. Plan to avoid steep solar slopes by late morning/mid-day to minimize the problem.

Many areas have massive cornices along ridge-lines so avoid slopes below these overhead hazards. Unlike the loose wet problem you will not get advance notice that a cornice is about to fail. Cornices can break much further back on ridges than expected and releases can be unpredictable during the spring.

Although not listed as an avalanche problem, large, powerful glide avalanches can release unexpectedly so avoid areas below steep unsupported slopes or rock faces.

In most areas previous wind slab will have become assimilated into the upper snowpack in the warm weather. The likelihood of triggering older wind slabs should be mostly over with and wind slab will not be listed as an avalanche problem. But continue to watch for isolated firm wind transported snow on previous, non-solar, lee slopes in the upper part of the above tree line.

Weather and Snowpack

A large upper ridge and warm air mass has been over the Northwest several days causing very warm weather. Friday was another day of light winds, sunny weather and the warmest temperatures by far so far this spring. Temperatures on Friday are well into the 50's and 60's F at many NWAC sites on both sides of the Cascade crest. This weather has been causing a spring avalanche cycle in most areas and has shifted concerns to heat related avalanche problems the past couple days.

Frequent March storms have built large cornices along ridges in many areas.

The mid and lower snowpack along the west slopes should generally be a stable mix of crusts and layers of moist and rounded snow crystals.

Recent Observations

On Tuesday the Meadows pro-patrol reported that northeast winds transported snow above treeline again to non-traditional aspects. Unlike areas further north, the warming trend on Mt. Hood was muted Tuesday and the snow surface remained firm near and above treeline with a mix of hard wind slab, sastrugi and wind scoured surfaces. In the below treeline terrain softening on solar aspects with increasing loose wet potential was seen in the afternoon. 

On Thursday the Meadows pro-patrol reported small ski triggered shallow loose wet avalanches on steep solar terrain Thursday morning then on all aspects Thursday afternoon.

NWAC pro-observer Laura Green toured from the Mt Hood Meadows ski area to the White River Canyon on Friday. There were no new large releases in the Canyon after the large releases seen earlier this week and about a week ago. Ski cuts gave only small loose wet releases and snow pits had layers of consolidated moist or wet grains in the upper snow pack.