Avalanche Forecast

Increasing cloud cover and ridgetop winds paired with relatively cool snow levels should help minimize wet loose concerns Thursday.  New loading is not expected to be significant during the daylight hours Thursday. 

However, wind slab may locally still be sensitive on a variety of aspects near and above treeline, especially in the south and central Washington Cascades were recent east winds loaded and cross loaded unusual aspects.  Watch for signs of cracking or firmer wind transported snow and approach open lee slopes with caution.

Remember to watch for cornices if you venture onto ridges and avoid slopes below cornices. Cornice failures are often seen during the transition to spring weather. Cornices have grown large recently and often break back much further than anticipated. 

March ended with a return to winter; a storm cycle that began last week peaked over the weekend and delivered about 1 to 3.5 ft of snow at NWAC stations near and west of the crest, with the highest totals near Mt. Baker and higher elevation sites. Natural avalanche cycles were seen over weekend with several skier/rider triggered slabs; more on these below.  An upper low that spun into California largely missed the PNW early this week, but easterly winds in the near and above treeline zones late Sunday night through early Tuesday have cross loaded slopes mainly over the south Cascades, but perhaps as far north as the central Cascades. Since Monday, afternoon temperatures have been climbing well above freezing and storm weaknesses from the weekend should have quickly settled and stabilized.  

Recent avalanche observations:  Increasing rain and snow, winds and warming temps began the increase in avalanche activity Friday with sensitive storm slab in the afternoon. On Saturday at Mt. Baker wet loose releases were reported below 4000 ft with building winds slab near and above treeline. Over the weekend, (likely Sat) TAY reports indicated that there were human triggered slabs up to 1' along the upper Shuskan Arm traverse and in the Blueberry Chutes area that may have resulted in a partial burial. Skier triggered storm slabs on lee slopes were reported in Silver Basin near Crystal on Saturday on the NWAC observation page. Sunday the Mt Baker and Alpental ski patrols reported isolated 4-8 inch storm slab avalanches releasing in storm layers. Also on Sunday, a TAY post told of several sensitive storm slabs up to 1' found on lee northerly aspects in Castle Bowl in the Tatoosh range. One skier triggered slab took a skier for a ride, but luckily no injuries were reported.   

 

Multiple snowmobile triggered shallow storm slabs on W-NW aspects near tree line were observed on Grouse Mountain near Mt Baker Sunday, 3/30 by NWAC observer Jeff Hambelton.  Photo: J. Hambelton 

NWAC observer Dallas Glass on Mt. Rainier Tuesday reported that the moderate east winds from earlier in the week had redistributed and cross loaded a variety of aspects above treeline, forming 20-40 cm of wind slab with a few natural avalanches.  Dallas also reported that with clearing Tuesday afternoon, small wet loose slides released on solar aspects. On Wednesday, Jeff Hambelton in the Mt. Baker area reported relatively cold snow still found on sheltered non-solar aspects and cornices that had grown larger the most recent storm cycle.  A few had released in last day or two, but generally only entrained shallow amounts of wet surface snow.