Avalanche Forecast

On Wednesday, light to moderate snow showers will add some additional low-density snow with decreasing westerly winds in the light to moderate range.

The snowpack above treeline still requires significant time to heal the recent heavy snow and strong wind loading. Rain has not extended significantly into this terrain. Expect large wind and storm slabs to be present in this terrain, but uncertainty is high here as we have no recent observations.

Since the recent cooling trend, consistent W and W-SW winds have formed small to large wind slabs, which will be found in the terrain near and above treeline. These wind slabs are hard. Watch for chalky texture or wind-stiffened snow and avoid steep, open slopes near ridgelines on Wednesday.

Storm slabs are less likely to be encountered on Wednesday, but you should keep alert for them. Significant new snow has fallen rapidly at all elevations in some locations, particularly around Mt. Rainier and Mt. Baker and new snow loading Tuesday night into Wednesday.

Small loose dry avalanches are possible in steeper terrain. Avoid steep slopes where the consequence of an avalanche may be significant.

A wet and potent storm system brought rain and snow with a strong cooling trend Monday. Variable amounts of snow gradually lower density snow fell on a wet snow surface and is bonding well to the newly forming crust. New snow amounts varied drastically and were highly elevation dependant. The most snow fell at Mt. Baker and Paradise with nearly 20" falling over the past 30 hours, as of Tuesday evening. Most other locations received less than 10" during this time period.

Above treeline treeline, deep snow still sits on a strong crust layer from 1/16. The 1/29 crust is not expected to be present at these elevations and although surface snow is right-side up, it is not known whether the older, lower density deeper layers have fully settled under the weight of the initially warmer, higher density snow that arrived on Sunday and Monday.

While most of the recent storm snow is not particularly cohesive, some locations such as the Crystal mountain area have storm snow instabilities.

The recent storm system also brought significant SW and W winds, which redistributed the storm snow significantly onto wind-favored aspects and stiffened snow, particularly in areas further south such as near Mt. Rainier. Wind slabs have been the primary avalanche concern following the recent storm on Tuesday.

On Sunday and Monday, warm and very wet weather (Mt. Baker Base picked up 3.5" of liquid water) acting on a cold and stormy period which had deposited nearly 13 feet of snow at Mt. Baker and 8 feet of snow on the mid-mountain at Alpental between 1/16 and 1/28 at Mt. Baker with significant but lower amounts elsewhere. The deep, lower density upper snowpack generally handled and absorbed the massive amounts of water surprisingly well, although a cycle of large natural avalanches was observed at Mt. Baker.

Recent poor visibility and frequent storms have limited recent observations above treeline.

Numerous natural avalanche cycles have occurred during the recent stormy period, particularly within the past week.

Observations

North

On Tuesday, Mt. Baker pro-patrol reported 17" of storm snow well bonded to the recent wet and slowly refreezing snow below. Although the ski area had been closed for two days, nothing budged in control work.

On Monday, Mt. Baker pro-patrol observed debris from several large natural avalanches that had run off of Shuskan Arm. Avalanche control work with large explosives resulted in several large avalanches with 2-3' crowns in area. 

NWAC professional observer Lee Lazzara was in the Mt Baker backcountry Saturday. Lee report several large natural avalanches in the backcountry area. Poor visibility limited detailed descriptions or more extensive observations. Observations found strong surface snow over soft weak storm snow from Friday. Shooting cracks and small slope tests all pointed to storm and wind slabs being easy to trigger. Even basic travel in the deep heavy snow was difficult.

Central

On Sunday, an avalanche forecaster on Snoqualmie Pass reported wet loose avalanches in steep, rocky terrain below treeline. Other reports including rain in the morning, runnels forming in the snow below treeline, and water draining through the recent snow.

Also on Sunday an observer on Snoqualmie pass reported tests results at 3,000ft indicating propagation on a melt-freeze crust about 2 feet below the surface. This crust may be harder to find at higher elevations.

South

NWAC Pro Observer Jeremy Allyn was in the Crystal Backcountry where he found intense snow showers alternating with broken skies. He found 12-16" of wind-redistributed storm snow in near and below treeline terrain with lots of evidence of reverse loading and cross-loading. Wind-loaded pockets were very deep (>90 cm) above 6000 ft. He found multiple storm snow interfaces, with notably reactive layer down 16" on a layer of 2 mm needles. On steep terrain, he was able to get some slab propagation, but the slab broke quickly into loose dry and didn't run far.

NPS Rangers reported 6-20+ inches of wind-distributed and wind-stiffened snow with moderate westerly winds depositing snow east-facing aspects. A snow test pit on an at 5700 ft revealed a moderate sudden planar shear down 12". A pencil-hard 1/29 rain crust was 4" thick at 5700 ft and existed in the terrain up to 7000 ft.

NPS Rangers reported a very large natural slab avalanche on Sunday from an east aspect at 6,800 ft in Van Trump Park on Mt Rainier. This released in recently wind drifted snow.