Avalanche Forecast

On Saturday morning, Alpental Pro Patrol triggered a size D3 avalanche with explosives, which gauged into the old wet snow from the past few days. Add this to the list of notable avalanches observed since Thursday morning as the Snoqualmie Pass zone has gone through an impressive avalanche cycle. Peak instability during the cycle lasted from Wednesday night through Friday morning, with professionals around the zone reporting widespread natural avalanche activity up to size D2.5. These avalanches were all wet in nature, with Wet Loose, Wet Slab, and Glide avalanches all being observed, and often intermingled. As the Alpental slide Saturday morning shows us, rain from the past few days still sits within the snowpack even after peak instability, and wet avalanches may still occur. With better visibility on Saturday, many glide cracks and further evidence of glide avalanches were observed. These lingering avalanches may become large and are most likely on big alpine terrain features, slopes containing glide cracks, or unsupported slopes such as cliff bands that did not naturally avalanche during the previous cycle.

Large debris from a size D3 wet avalanche triggered by Alpental Patrol Saturday morning. Photo: Aaron Opp

Update: January 24th 2020 (The regional synopsis is updated every Thursday @ 6 pm)

During the afternoon of January 23, 2020 one person was buried and killed by an avalanche that released from the roof of a home north of Blewett Pass near Highway 97. The elevation was approximately 1,700ft above sea level. She was found underneath 4 to 5ft of debris. She was discovered and excavated some time after the accident, where CPR was performed. Additional emergency response arrived within 15 minutes, but they were unable to revive her.

Our deepest condolences go out to the family and friends of the victim.

January to Remember

A parade of storms since the New Year began brought relentless precipitation, and impressive snowpack growth throughout the region. Areas along the west slopes of the Cascades have rarely gone more than 24-48hrs without precipitation. In the past three weeks, the Volcanoes and Passes received 20-28in of water equivalent, translating into incredible snowfall totals - Mt. Baker Ski Area reported 240in of new snow since January 1. The majority of NWAC weather station sites are reporting snow depths well over 120% of normal for this time of year. Ongoing precipitation and fluctuating snow levels have maintained elevated avalanche danger throughout the month, with avalanche warnings issued for nearly all forecast zones on 4 separate days (January 6, 7, 12, 23).  

Snow depth imagery for the Northwest Region on January 23, 2020. Many areas in the Cascades and Olympics show well over 100 inches of snow on the ground. Image courtesy of NOHRSC Regional Snow Analysis. 

Location

January 1-23 Precipitation (Water Equivalent)

Hurricane Ridge

14.79”

Mt Baker Ski Area

28.65”

Harts Pass

11.2”

Stevens Pass

20.26”

Leavenworth

4.01”

Snoqualmie Pass

25.43”

Paradise, Mt Rainier

24.13”

Mt Hood Meadows

22.34”

Table 1: Precipitation totals for select weather stations January 1-23, 2020. Huge numbers at Baker, Rainier, Hood, and the Passes and there is still another week left this month.

MLK Weekend and a Pattern of Rain on Dry Snow

After a prolonged cold period with arctic air and lowland snow, MLK weekend brought unseasonably warm temperatures and a rapid thaw. High snow levels and rain caused wet avalanche activity throughout the region January 18-19. A few very large natural avalanches occurred at upper elevations where all precipitation fell as snow. A cooling trend followed, creating a pronounced crust that is now buried in almost all forecast zones. Cold, dry snow January 21-22 was followed by a rapid warm-up and the most significant rain on snow event yet, causing avalanche warnings on January 23 for 5 of our 10 forecast zones.

The crown of a very large avalanche around 10,000ft on the Newton Headwall of Mt Hood which likely occurred during the storm late last week. 01/19/20 Photo: Kevin Kayl

The buried MLK crust is widespread throughout the region and a prominent marker in the snowpack. Crystal Backcountry 01/20/20 Photo Jeremy Allyn

One More Week To Go

January isn’t over yet, and the long term forecast continues to show an active and wet weather pattern for the Northwest. The low-snow, drought-like conditions of the early season seem like a distant memory at this point. We’ve certainly made up for lost time in 2020, and this already impressive month looks to end with a bang.