Avalanche Forecast

Additional loading in showers Wednesday will transition into increased frontal snowfall and strengthening winds Wednesday night and Thursday morning while remaining cool.  This should add additional loading from storm layers to new wind slab over existing deep storm slabs and older wind slab layers.  Strong westerly winds through early Thursday will build large wind slab layers on a variety of lee aspects ranging from NW-SE while some other cross loaded aspects remain possible. 

Expect snow conditions to be touchy on Thursday and very sensitive to human triggers.  The most likely slopes to trigger avalanches should be mainly on lee NW thru SE aspects. Triggered avalanches are likely to start and stay in the new snow as of Thursday morning, however the potential exists for some very large avalanches in specific areas that release down to older storm and stiffer wind slab layers or the rain crust from last week. Recently formed and sensitive cornices along ridgelines are an example of a natural trigger that could be large enough to trigger a much deeper and very destructive slide.

Stick with very conservative terrain choices and let all the recent snow and associated water weight received over the last 9 days have time to settle.  

Recent Northwest Weather

An extended mild and mostly dry period occurred over the latter half of January which allowed a variety of crusts to form. Very cold weather followed in early February which produced low density snowfall and strong temperature gradients in the upper snowpack that allowed near surface faceting and broke down previously strong crusts buried in late January. During the last week the Pacific Northwest has been pummeled almost daily by frontal systems producing periods of strong winds and intense snowfall accumulation at fluctuating and generally moderate snow levels.

Water equivalents in the Olympics at the NWAC weather station and the NRCS Snotel at Waterhole over the last week are 6-7 inches with snowfall over 5 ft. Expect wind loaded slopes to hold much more new snow from the past week than the generally sheltered weather stations.  About 24" of new snow has fallen in last 36 hours ending 5 pm Wednesday.  

Observations near Hurricane Ridge

At Hurricane Ridge this weather has been building deep new snow over a rain crust from Wednesday, which lies over colder lower density snow from earlier in February. In sheltered non-solar aspects, surface hoar may be buried above the late January crust.

A park ranger and NWAC observer Tyler Reid at Hurricane Ridge Friday reported one ski triggered D2 avalanche on a northeast slope at 5200 feet on Friday.

Snow pit tests by Tyler on Saturday on a SE aspect @ 5200 ft gave moderate to hard, sudden planar results with potential to propagate across the failure plane on the melt freeze crust 20 cm down (this layer is now further down).  You can view a great video by Tyler explaining his test results. 

A natural avalanche, estimated at size D2-3 with up to a 3' crown was visible below the Hurricane Ridge road at about 5100 ft on a wind loaded NE aspect on Monday.

Limited snow at the lowest elevations will limit the avalanche danger but be aware that avalanche paths on solar aspects and lower elevations are finally beginning to fill in. The mid and base pack should still consist of mostly stable crusts and melt form layers from periods of warm weather earlier this winter.