Avalanche Forecast

Cool temperatures, moderate snow showers and periods of moderate S-SW winds will continue to deposit new snow and further build existing wind and storm slab layers, especially in the north zone, containing the Mt Baker area where heavier showers are expected.

Note that a refreezing 1/17 rain crust will continue to harden and may provide a bed surface for wind and storm slab avalanches on Friday.

Cascade West-North above treeline terrain will have very dangerous avalanche conditions Friday with large and potentially deadly wind and storm slabs. Travel in this area should be avoided until well after these slabs have time to stabilize. 

Elsewhere, building but shallower wind and storm slabs should maintain dangerous avalanche conditions. Storm slabs may form quickly and become sensitive to human triggering, especially in those areas receiving the greatest amounts of new snow (more than about 8" of new snow accumulated) and higher snowfall rates (extended periods of more than about 2" per hour). 

Conservative terrain choices will be essential in most areas, especially higher terrain and wind exposed terrain. Best to travel in wind sheltered, lower elevation terrain well away from steep open slopes until this new storm snow stabilizes. 

Lower snowfall amounts anticipated in the Cascade Passes will make storm slab less massive/reactive and wind slabs generally smaller, reducing danger relative to other areas.

 

In the Mt Baker area, over 4 inches of water equivalent has fallen since Tuesday night! Winds have ranged in the 40-60 mph range much of that time. Above treeline, much if not all that water has fallen as snow, likely 3-4 feet! The combination of heavy snowfall and very strong winds are making very dangerous avalanche conditions above treeline where deep wind and storm slabs have formed.

Near and below treeline the precipitation began as rain and transitioned to snow. This has caused less dangerous conditions with new snow forming good bonding to the old rain soaked snowpack. However, heavy snowfall and moderate to strong winds have built increasing wind and storm slabs at progressively lower elevations. There are still dangerous avalanche conditions with new and increasingly deep wind and storm slabs deeper of 1-2 feet as of late Thursday.

The old rain wet snow continues to gradually re-freeze and form a new crust layer.

The older snowpack has undergone several rain or warm periods and remains void of any significant layers of concern.

Observations

North

Thursday morning, the Mt Baker Pro Patrol reported fresh wind slabs were sensitive to ski cuts and were releasing in the 4-5 inch range, near treeline. Winds were reportedly very strong along ridges and actively transporting the new snow. 

On Wednesday afternoon, Mt. Baker Pro Patrol observed evidence of several large, natural loose wet avalanches visible on Shuksan arm at approximately 3000 ft. The avalanches are suspected to be from earlier Wednesday. 

Central

NWAC forecaster, Dallas Glass was on Skyline Ridge at Stevens Pass Thursday and reported new storm snow of 8 inches at 4000 feet and 14 inches above 5000 feet. The bonding was good to the old rain wet snow. The crust had yet to re-freeze but was in the process. There was evidence of recent wind transport with a fresh natural avalanche having released on a steep east face about 5300 feet, likely during a brief warm up Wednesday night. There were storm slab layers noted from fluctuating temperatures overnight, but were not sensitive to human trigger in that location. 

South

No recent observations