Avalanche Forecast
Regions: Olympics.
With this ongoing warm and sunny pattern, you will find the lowest avalanche danger in the morning when cool temperatures and a frozen snow surface limit the hazard. As the sun and warm temperatures begin to affect the snow, turn your attention toward loose wet and cornice avalanches - isolated large avalanches may be possible. When you find more than 4” of wet snow on the surface, it’s time to change aspects to where the snow is still a bit more frozen.
Discussion
Our most recent observations were from Sunday when a skier triggered a 20 ft wide avalanche within 6-8†of recent storm snow on the 20th of June slide path.
Temperatures warmed drastically Sunday night, with at least 48 hours of above freezing temperatures by the time you hit the slopes on Wednesday.
The result of the sustained warmth across the region is that we’re now several days into this loose wet pattern and many small natural loose avalanches have probably already occurred. Clear skies and cool temperatures should help the snow surface freeze in most locations. Expect that to change quickly Wednesday morning as a strong March sun helps temperatures soar, softens the snow, and increases the avalanche danger. Pay attention to the snow surface. When you start to notice your boot sinking in near your ankle, it’s time to change aspects. Unstable snow will move around the compass as the sun moves across the sky. Don’t forget about how this could affect slopes you’ll need to cross to return to your car later in the day.Â
On Wednesday, we’ll be entering our 3rd full day of above freezing temperatures. Water may begin to impact layers deeper in the snowpack. Lingering large overhung cornices are losing strength due to sustained warmth and may fail without warning. Either water percolation or large triggers such as cornices or loose wet avalanches could trigger isolated larger avalanches. Limit your exposure to large complex terrain during the warmest parts of the day.
Forecast Schedule
For the 2019-20 winter season, avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week, No Rating will be issued but forecasts will include expected conditions and relevant travel advice. If you are out in the Olympics, share your backcountry observations.
Snowpack Discussion
March 12, 2020 (The regional synopsis is updated every Thursday @ 6 pm)
From March 6th to the 12th the Pacific Northwest experienced a few small storms and a few notable days for people and avalanches. Light to moderate snow accumulated slowly over a period of a few days, and avalanche danger increased from Low to Moderate over the weekend of March 8th. The exception was the West North zone, which won the snowfall competition this week. 18-24†of new snow was observed in the Mount Baker area on the 6th, and 10†of new snow on the 11th. Avalanche danger reached Considerable there for storm slab, wind slab, and loose wet avalanche problems.Â
People, complicated avalanche terrain, and lots of avalanches. Bagley Lakes Basin, West North zone. Photo by Nathan Resick, March 8, 2020.
Loose dry slides initiated by skiers in big terrain. No one was caught or carried. East Central zone. March 8, 2020. Matt Primomo photo.
The snow fell with minimal wind, and accumulated slowly over firm suncrusts or wind stiffened surfaces. Thicker cloud cover inhibited the sun in areas where 4†to 12†of snow accumulated over the course of a few days. Cold overnight temperatures allowed the low density snow to weaken. By the 8th, the clouds broke up enough to allow strong radiation to change snow surfaces. When the sun finally did hit the snow, it quickly caused loose avalanches in steep terrain.Â
An active weekend for people and avalanches:Â
Many areas experienced some form of loose avalanche activity from March 6th to 9th. Sunday, March 8th was the day that recorded the most widespread avalanche activity across the region. The size of these avalanches were directly related to the amount of new snow that had recently accumulated in that area, and the size of the terrain.Â
West North zone on March 8, and West South zone on March 8th. Uphill and downhill tracks got covered by debris. Photos by Zack McGill and Dallas Glass.
We as a community can look back at, and learn from these few days. Numerous human triggered slides occurred, some were slabs but the majority were loose. A number of catch and carries were observed, and many more likely went undocumented. Luckily, no injuries or burials were reported. Observers across the region reported lots of instances where previous tracks got hit with debris, either from human triggered or natural avalanches.Â
As the days get longer and folks begin to step into the alpine zone and bigger terrain more frequently, it is important to keep a humble attitude. Continuously evaluate route selection with potential for loose wet and cornice falls in mind. Check the mountain weather and avalanche forecasts for the most up to date info. Enjoy the backcountry, be safe, and let us know what you see out there!
-MP
Solo snowboarder aired into this slope, and went for a ride but was not buried or injured. Slide took out the corner of a skin track. Bagley Lakes Basin, March 8, 2020, Zack McGill photo.
Wind slab triggered by a skier at 7,500ft next to the popular route on Mt St Helens. The skier wasn’t caught or carried. Andy Goodwin photo, March 8, 2020.