Avalanche Forecast

The avalanche danger will shift to new Wind and Storm Slabs building with and after a frontal passage Wednesday night. Further storm showers are expected Thursday. Moderate winds with light to moderate snowfall at cooling temperatures will make triggered slab avalanches likely by Thursday, especially on steep slopes receiving wind transported snow near and above treeline. Use visual clues such as fresh cornices, wind drifted pillows and cracks in the snow all indicating that you could trigger a Wind Slab avalanche.

Shallow Storm Slabs may build over a newly forming crust. Watch for and avoid deeper drifted snow on steep slopes. 

Cooling temperatures will allow for old wet snow to consolidate and refreeze, limiting any Wet Snow avalanches. 

Watch for other spring hazards such as recent cornices along ridges, open glide cracks and opening creeks.

New wind and snow is arriving at cooling temperatures late Wednesday. This is allowing old wet snow to begin re-freezing while building new Wind and Storm Slab layers.

A front brought light to moderate rain and wind to the west slopes of the Cascades Tuesday. Rainfall was locally heavy in the Mt. Baker area during the day. Snow levels fell to around 5000 ft by late Tuesday afternoon.

Very warm temperatures and sunshine Monday quickly allowed the weekends 1-2 ft of snowfall to become wet and weak, causing widespread large wet snow avalanches on many steep slopes on all aspects. The majority of these avalanches were Loose Wet but several large Wet Slab avalanches released on some steep slopes as well.

The 4/1 firm crust may still exist in some areas, it has most recently been identified in the Crystal area 1.5-2 ft down. 

Out of the weak layers that we've tracked through the season, the 2/8 crust can still be identified in many areas 5-7 feet below the surface. This interface was associated with the 2/13 facets. Though it's unlikely, if significant water pools on the crust, it could result in very large and dangerous Wet Slabs.

Observations

North

No recent observations

Central

NWAC forecaster Dallas Glass traveled in the Stevens Pass area Wednesday. The upper snowpack remained wet allowing for widespread triggered Loose Wet avalanches, beginning small but entraining significant wet snow and becoming large. There was evidence of recent widespread large wet snow avalanches following the weekends strong storm cycle, however there were many slopes that did not avalanche, holding deep wet snow. Travel conditions were less than desirable. 

Stevens Pass DOT and Stevens Pass Pro-patrol reported large and destructive avalanches during control work that released as soft slabs with explosives and quickly entrained wet snow at lower elevations on Monday. In a section of the ski area with minimal skier traffic on the east end of Cowboy Ridge, this explosive triggered slide (SS-AB-D2.5-R3-O) on a north aspect produced 4-5 ft of debris as it entrained old saturated snow below.  

Pro-observer Matt Primomo observed recent natural wet snow and storm snow avalanches in the Stevens Pass backcountry over the weekend, including this recent Litchenberg Wet Slab Avalanche on a SE aspect at 5200'. 

Pro patrol at Alpental Sunday reported about 1 ft of new storm snow that was sensitive to ski triggering, releasing soft slab avalanches of 8-12" and running long distances, entraining all the recent snow, running on the old wet snow surface. At lower elevations the new snow was easily releasing as Wet Loose avalanches by skis. 

South

NWAC professional observer Jeremy Allyn traveled in the Crystal backcountry Monday 4/9. Through mid-day, Jeremy found poor travel conditions as the surface crust quickly broke down with moist or wet snow in the upper snowpack.  Recent large Wet Loose and one Wind Slab avalanche from the weekend were observed in surrounding terrain.