Avalanche Forecast

Expect quiet weather for the next 24 hours before an active pattern begins Tuesday bringing heavy snow, rain, and breezy conditions.

Generally stable avalanche conditions exist in the Mt. Baker area. On Sunday, observers reported a breakable crust on slopes up to 5500ft. The crust created challenging travel conditions and made any lingering wind slabs even more stubborn to trigger. With sunny skies and high temperatures in the low 40s F, rocky sun-exposed slopes produced wet loose activity during the afternoon. 

A handful of shallow human-triggered wind slab avalanches (D1) were reported over the weekend and occurred on steep wind loaded slopes in north-facing terrain above treeline. At the highest elevations, you may still be able to find areas where winds drifted snow into firmer and thicker slabs. Pay attention as you transition into wind affected terrain. Watch for cornices, pillow-like drifts, and hollow sounding snow as indications that old wind slabs could exist nearby. Any wind slabs you can still trigger would likely be small and easy to identify and avoid.

Small skier-triggered wind slab (D1) that broke 6-8in deep on a north aspect at 5400ft on Ptarmigan Ridge. 12/28/19 Photo: Mark Flexer

Wet loose avalanches ran far distances on the west-facing slopes of Goat Mountain East. 12/29/19 Photo: Nick Vincent

December 26, 2019 (The regional synopsis is updated every Thursday @ 6 pm)

No matter where you are in the northwest, the snowpack looks a world different than it did a week ago. A major storm, widespread avalanches, developing weak layers, and an initially thin snowpack made for a hectic week. Let’s take a look at a few large scale trends for our holiday season. 

A very large natural avalanche (D3) on the Shuksan Arm near Mt Baker that occurred during the storm cycle. Photo: Adam U. 

Wet and Wild

“Some of the highest precipitation rates I’ve ever seen.” “Absolutely puking!” “Rivers running in the streets.” “Snowing snow hard I can’t see my hand in front of my face.” These were all statements we heard describing the wet and wild storm that impacted the Northwest from about Thursday (12/19) through Sunday night (12/22). Water totals were staggering in many locations (Table 1). For Hurricane Ridge, Mt Baker, Washington Pass, and high elevation terrain this deluge translated into significant snowfall. However, warm air in the central and southern parts of the region brought rain well into the near treeline bands. Whether your favorite spot saw rain or snow, four things are clear. 1. This was a huge loading event. 2. A widespread natural and triggered avalanche cycle (up to D3) occurred. 3. Avalanche danger spiked during and just after the storm before trending down through the week. 4. The snowpack changed dramatically. 

Location

Precipitation 12/19-22

Hurricane Ridge

4.97”

Mt Baker Ski Area

7.35”

Washington Pass

3.53”

Stevens Pass

6.28”

Leavenworth

2.94”

Snoqualmie Pass

7.89”

Crystal Mt Ski Area

7.45”

Paradise, Mt Rainier

6.57”

Mt Hood Meadows

2.18”

Table 1: Precipitation totals for select weather station locations December 19-22.   

The Emergence of Persistent Slab Avalanche Problems

Coming out of this huge loading event, there was hope that many of the early season weak layers had been destroyed. Unfortunately, this was not the case in some locations. Old weak snow layers reared their heads in areas east of the Cascade Crest and near Crystal Mountain. While the exact extent and character of these layers can differ slightly, most locations are finding a layer of weak sugary facets associated with a crust about a foot above the ground. Persistent slabs are tricky to assess. Do not solely rely on snowpits and snowpack tests to help you choose terrain. How will these layers change going forward? Only time and observations will tell. 

You may find weak sugary facets near a crust about 12 inches above the ground similar to what you see here. Photo: Jesse Charles

Low Tide Snowpacks During the Holidays

The storm this past week definitely helped the meager early-season snowpacks in all locations. Areas like Hurricane Ridge, Mt Baker, and Washington Pass experienced a jump of 20 or more inches in their snow depths over the past week. However, even with these increases, an early season snowpack still describes most locations. Expect numerous obstacles as you travel including open creeks, rocks, and trees. With this thin snowpack, limited access, and difficult travel we still have limited observations in some regions. 

Open, deeply incised creeks in the Alpental Valley. Photo: Dallas Glass

Lack of information leads to a higher than normal degree of uncertainty. If you travel to higher elevations or more remote trailheads, recognize you could experience different conditions than the forecast suggested. You can help us fill in the gaps by submitting your observation here. 

Happy Holidays! 

-Dallas Glass