The Bottom Line: While Low avalanche danger doesn't mean no danger, avalanches will be unlikely on Wednesday. Crusts may create challenging conditions for some backcountry travelers. Use standard backcountry travel practices such as minimizing exposure to avalanche terrain and carrying a transceiver, shovel, and probe.
Snow and Avalanche Discussion
During low danger, continue to use standard practices and protocols for winter travel in the mountains. This includes minimizing exposure to the avalanche hazard and carrying standard rescue gear. Avalanches are unlikely, but not impossible. It's important to keep in mind the consequences of an avalanche in extreme terrain or that of a non-avalanche related injury or gear malfunction in a remote setting.
Cooling temperatures following a period of calm, quiet weather set the stage for minimal avalanche concerns. Recent calm weather created a variety of snow surfaces that change with aspect and elevation. Surfaces that will be buried by the next round of snow include: breakable crust, old wind transported snow, rime, and surface hoar. Track these interfaces as they get buried by coming storms. See the regional synopsis for more on how the recent weather affected the snowpack.
Regional Synopsis
January 15, 2019
We’re about a month into our avalanche season and well into the heart of winter. In the past month, the snowpack has grown from near non-existent to over a 100 inches deep at Mt Baker. Remote weather stations show most snow depths across the region are at 62-77% of normal with Mt Baker and Crystal Mountain at 93% and 90% respectively. Check out the latest climatological snow depths for more details.
Much of the last month has been filled with elevated avalanche danger, numerous avalanche warnings, and several widespread large natural avalanche cycles. While the active weather patterns and growing snowpack have been a welcomed sight, it’s been hard to catch our breath. Quieter weather in the middle of January has offered a break in the non-stop storms and allowed avalanche danger to drop in all zones. Looking forward to more unsettled weather, there are a few things on our mind here at the avalanche center.
Calm weather in mid-January A period of calm weather heading into the middle of the month shaped a variety of snow surfaces. As of January 15th, you could find a range of wind transported snow, crusts (both thin/breakable and thick/supportive), rime, surface hoar, and weak, dry snow on the snow surface. This will determine our next interface to track, as storm snow accumulates. The big take-away is that you should track surface conditions from the 16/17th and how that interface changes based on aspect and elevation.
There were a few interesting weather factors during the mid-January calm weather that contributed to surface variations. While clear skies and warm temperatures were the norm in many locations (especially west of the Cascade Crest), temperature inversions and cold east flow cooled valleys and passes. The sun is still low in the sky and hasn't been strong enough to drive significant melting of snow surfaces. Hence, many slopes developed only thin crusts. Additionally, fog limited both the effects of the sun and surface hoar growth at lower elevations and in valleys.
Old Persistent Weak Layers A high elevation rain event on January 3rd did us a favor in many locations. Besides heavily stressing old weak layers, the rain created a very strong melt-freeze crust, making it extremely difficult to trigger deep avalanches.
There are a few exceptions, and they can be found mainly in the eastern forecast zones. The East-North zone around the Methow Valley and WA Pass did not experience significant rain above 5500 ft, potentially leaving some older weak layers intact. Areas further east including, but not limited to, Icicle Creek and the Wenatchee Mountains did not receive enough rain to form a strong thick crust. In all of these areas, older persistent weak layers are still suspect.
An avalanche on a persistent weak layer in the East-Central zone. Photo: Matt Primomo
Higher Elevations and Remote Trailheads Stormy weather over the last month has been keeping most of us closer to common trailheads and recreating at near and below treeline. With nice weather on tap, some of you may be thinking about heading into higher elevation terrain and exploring around more remote trailheads. If you are heading out, take time to consider a few key pieces of information.
At higher elevations, the snowpack is very deep and wintery. This stands in stark contrast to the lack of snow at lower elevations. The snowpack you’ve seen on previous outings this winter doesn’t represent what you will encounter at higher elevations.
We have not received much information about the above treeline nor remote location snowpacks. That means we have a high degree of uncertainty in these areas.
You will need to make observations as you travel to confirm if the avalanche forecast is applicable to the area where you are traveling. When observations lineup with the information in a forecast, it's valid. If you see observations that don’t lineup, it’s time to take a step back.
If you are heading into our regions highest alpine terrain, remember, NWAC forecasts apply to areas below the main Cascade crest or about 8000 ft. So, if you plan to travel to higher elevations on Mt Baker, Mt Shuksan, Mt Rainier, Mt Hood, or similar areas, you will need the skills and information to evaluate the terrain and snowpack.
If you’re heading into higher elevation terrain, remember we don’t have much information about these snowpacks, and therefore have a higher degree of uncertainty. Photo: SimonTrautman
We’d like to thank our NWAC Community for all the wonderful public observation this year. If you are heading out into the mountains, we appreciate you taking the time to let us know what you saw. This is a great way to contribute to the creation of your avalanche forecast. You can submit observations here.
