Avalanche Forecast

Another break between systems is expected Thursday as brief high pressure transits the region. There may be a few showers early Thursday to midday, but little accumulation is expected. Winds should be light Thursday.

This should allow for recent storm snow and any wind slabs below ridges to begin settling.  The greatest concern Thursday should be on steep lee slopes below ridges that may have wind transported snow deposited Wednesday. These slopes should range from NW-E facing. 

In addition, watch for any recent cornice formations along ridges and give these early season cornices a wide birth as they may be fragile.   

In much of the lower elevation, below treeline band, there is insufficient snow to produce avalanches, but watch for early season hazards such as rocks and creeks.  Avalanche problems should be limited to the upper part of this elevation band and higher elevations.

Weather Discussion for the Cascade West Slopes

After a stormy Thanksgiving weekend, which especially hammered the Mt. Baker area, a frontal passage Sunday night was followed by a period of NW flow that dropped 4-12 inches of snow along the west slopes of the Cascades through Monday morning. A few additional inches accumulated during the day Monday with light to moderate showers and snow levels around 3500-4000 feet. Tuesday was a break between weather systems.

The most recent storm began about midnight Wednesday, Nov. 30 with new snow ranging from 8-14 inches as of late Wednesday afternoon at most west slope NWAC stations. Ridgetop winds initially were moderate southerly, shifting to more westerly and diminishing greatly by Wednesday afternoon.  

Recent Reports for the Cascade West Slopes

Monday, Alpental pro-patrol found a homogeneous 2 ft of recent storm snow on top of older snow at the top of their hill with an average snowdepth of 3 ft (1 m) above 5000 ft although snowdepths varied widely depending on wind effect. Low quality shears were found in snowpack tests and there were no layers of concern within the new storm snow.  

DOT professionals were on Chinook Pass Monday and found a well bonded snowpack with generally dense surface snow.  

Wednesday, NWAC pro observer Dallas Glass in the backcountry of Crystal Mountain found a right side up snowpack with 4-6 inches of storm snow well bonded to the older settled snow. No avalanches were seen and no evidence of wind effects or layers of concern was noted.   

Also Wednesday, Mt. Baker pro-patrol reported only minimal recent storm snow avalanches from control work. These avalanches ranged up to about 5 inches and all within the most recent storm snow since midnight. No significant storm layer or older layers were noted. 

In general, much of the below tree-line elevation band still has plenty of terrain anchors, but these are filling in quickly with each passing storm.  The near and above treeline bands have been filling in throughout the west slopes of the Cascades, but are the most shallow in the Pass zones including Stevens, Snoqualmie and White.