Olympics

March sunshine will destabilize plentiful low-density snowfall to produce potentially large wet avalanches.  Anticipate the sun's daily trajectory and avoid exposure to steep slopes directly receiving the sun's rays.  You can also trigger a slab avalanche large enough to harm you on any slope over 35 degrees.

Hurricane Ridge picked up 12+ inches of snow in the past 18 hours. This snow may sit on a rain crust up to near treeline elevations formed on Saturday during a period of briefly warm temperatures. The recent snow arrives on the heels of 20"+ of new snow from Thursday afternoon through Saturday afternoon.  At elevations above Saturday's rain crust, you may now find 2+ ft of settled snow above the 3/4 melt-freeze crust. The 3/4 crust was thicker on sunny aspects that had gone through several melt-freeze cycles. Below the 3/4 crust, the upper snowpack is generally increasingly dense the deeper you dig.  The 2/23 crust can still be found 12-16" below the 3/4 crust.  Weak snow (facets) were observed below this crust last Thursday but avalanches on this layer seem unlikely. The mid-Jan crust layer that has been so prominent in the Cascades can still be found in the Hurricane Ridge area albeit at much shallower depths; ~4 ft below the surface.  Avalanches down to this layer have not been observed in the Hurricane Ridge area in over a month but it's still worth tracking as we wait to see what March has in store for us.  

Avalanche concerns involve the new snow combined with sunshine on Monday. Slab and wet avalanches could be large at upper elevations given the plentiful recent snow that still needs time to settle.

1. Despite the cool weather, we expect the strong March sunshine to win the battle on W-S-E aspects. As the sun impacts a slope, trees will begin shedding their snow, rollerballs will gain size and momentum, opening the door to natural or human-triggered avalanches. Check the depth of snow above the most recent crust in your area; the deeper the crust, the larger avalanches are likely to be. Wet avalanches will be large where more than 1 ft of snow lies above the most recent crust. Transition to cooler shaded aspects and limit your exposure to sun-exposed slopes above.
2. Heavy snow fell repidly enough to form storm slabs fell on Sunday (around 8" in 5 hours). The unstable snow will take another day to heal. Use small test slopes and quick pits to check the bond at the new/old snow interface and for mid-storm layers. Storm slabs may be more reactive where they have a crust to run on. Only venture onto slopes steeper than 35 degrees if you have fully evaluated the storm layers on similar aspects. Near and above treeline, the danger will be most significant where SW winds created larger drifts on lee slopes. Wind-loaded areas may be found below freshly corniced ridgelines and where you find lens-shaped pillows on the slope.
3. Use care along ridgelines where cornices are growing larger during this storm cycle. Make sure there's a healthy buffer between you and where cornices may break.   A group at Stevens Pass had a scary encounter last week with a cornice release during poor visibility.  While traveling below ridgelines, always keep an eye toward the slopes above you. A cornice release on Monday would likely trigger an avalanche on the slope below.   

The snowpack is quite deep and healthy for this time of year, 130% of normal as of March 1st. 

Make sure to check out the Conditions blog for more info about the very large avalanches that have released throughout the central and southern Cascades over the past two weeks.  There are some impressive photos of a few of these monster slides included in the media reel below.  

2020-21 Forecast Schedule: Avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week when the Hurricane Ridge road is closed, forecast information will be updated daily to include expected conditions and relevant travel advice under the No Rating label.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.