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West Slopes North - Canadian Border to Skagit River

Issued: 8:06 AM PST Sunday, February 4, 2018
by Dennis D'Amico

NWAC avalanche forecasts apply to backcountry avalanche terrain in the Olympics, Washington Cascades and Mt Hood area. These forecasts do not apply to developed ski areas, avalanche terrain affecting highways and higher terrain on the volcanic peaks above the Cascade crest level. 

8 AM Update: Changed Wet Slab Avalanches to Wind Slab Avalanches Above Treeline in Mt. Baker Zone (West Slopes North)

Avoid avalanche terrain at upper elevations and where slopes are steeper than 30 degrees. Use extra caution if traveling in areas where avalanches may run or stop. Wind slab avalanches may start at upper elevations and run long distances, entraining wet snow at lower elevations while becoming very large and destructive. 

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Avalanche Problems for Sunday

Wind Slabi

Wind slabs can take up to a week to stabilize. They are confined to lee and cross-loaded terrain features and can be avoided by sticking to sheltered or wind scoured areas.

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Loose Weti

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.

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Cornicesi

Cornices are easy to identify and are confined to lee and cross-loaded ridges, sub-ridges, and sharp convexities. They are easiest to trigger during periods of rapid growth (new snow and wind), rapid warming, and during rain-on-snow events. Cornices often catch people by surprise when they break farther back onto flatter areas than expected.

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Forecast for Sunday:

Expect dangerous and complex avalanche conditions today due to heavy rain and snow and warming temperatures. Wind slab avalanches above treeline can be very large and can pose serious consequences. Avalanches big enough to bury a car are not out of the question today. The most dangerous slopes are above treeline, where previously dry snow will become either saturated with water for the first time or continuously loaded by wind driven heavy wet snow due to a snowline that oscillates between 5000-6000 feet. 

Wind Slab avalanches hold today’s gravest consequences. Deep wind slabs may form on a variety of aspects today and will be difficult to manage. Use extra caution when crossing the tracks and runouts of avalanche paths and where you are exposed to overhead avalanche terrain. Wind slab avalanches may start at upper elevations and run long distances, entraining wet snow at lower elevations while becoming very large and destructive. 

You are most likely to trigger or see Wet Loose avalanches. Many of these slides ran in the past couple days. While these avalanches may be the most predictable of today’s problems, they could still be forceful or large enough to injure or bury you. Avoid traveling through or above terrain such as or cliffs, gullies, or rocky slopes where the consequences of being caught in an avalanche could be increased.

Cornice fall and Glide avalanches have become possible due to rain and rising temperatures. Both could be very large and dangerous. Avoid areas with visible glide cracks or where known rock slabs underlie the seasons snowpack. Give yourself an extra wide margin of safety near ridges that could hold cornices, and avoid slopes with cornices overhead.

Avalanche Summary:

Mild wet weather changed snow surface conditions in the Mt Baker backcountry Friday and Saturday. Below 5000 feet, warm temperatures and rain created moist to wet avalanche conditions. This was highlighted by a natural Loose Wet avalanche cycle on all aspects and some cornice fall.

Above 5000 feet, a few large natural Wet Slab and Wind Slab avalanches occurred during peak warming and precipitation Friday. These elevations will receive close to 2 inches of rain on Sunday, and have the potential to produce very large wet avalanches

Across the area 2-3 feet of settled storm snow accumulated over the past week.

Observations

Mt Baker Ski Patrol reported rain to 5000 feet Friday and Saturday with a natural loose wet avalanche cycle occurring in the adjacent backcountry terrain. They observed debris from larger slab avalanches on the Shuksan Arm and Mt Herman as well as cornice fall near Table Mountain.

NWAC Forecaster, Dallas Glass, was greeting backcountry travelers at the Heather Meadows trail head on Saturday and reported snow lines waivering between Heather Meadows (4,200ft) and ridge tops. Dallas observed numerous wet loose avalanches in the Bagley Lakes area.

NWAC pro-observer Lee Lazzara traveled in the Canyon Creek area Thursday. Lee found 15-24 inches of recent snow over the 1/29 crust. Wind Slabs were noted in terrain near ridgeline but poor visibility limited observations near treeline.

No Corresponding Mountain Weather Forecast Available

USE AT YOUR OWN RISK

This Backcountry Avalanche Forecast is provided in conjunction with the US Forest Service, and is intended for personal and recreational purposes only. Safe backcountry travel requires preparation and planning, and this information may be used for planning purposes but does not provide all the information necessary for backcountry travel. Advanced avalanche education is strongly encouraged.

The user acknowledges that it is impossible to accurately predict natural events such as avalanches in every instance, and the accuracy or reliability of the data provided here is not guaranteed in any way. This forecast describes general avalanche conditions and local variations will always occur. This forecast expires 24 hours after the posted time unless noted otherwise.