This information was published 11/17/2018 at 7:00 AM.
NOT THE CURRENT FORECAST
This is an archived avalanche forecast.
The Bottom Line
General Bulletins are issued when unstable snow may exist within our forecast areas but before 5 scale avalanche advisories begin. Please remember that avalanches can occur before 5-scale avalanche forecasts are issued.
A series of storms over the past week brought nearly 30 inches of snowfall to the summit of Mt. Washington. This new snow continues to rapidly alter coverage. Developed avalanche paths are still the exception rather than the rule, but skiers and climbers will likely be drawn to these developed snowfields. Early season conditions still exist in the alpine and are even more pronounced at lower elevations. Areas with a more developed snowpack, like the south side of Tuckerman Ravine, have shown the ability to avalanche already with natural activity observed earlier this month as well as in October. The adage, “If there’s enough snow to ride, there’s enough snow to slide” is certainly true and should motivate you to make careful snowpack assessments this weekend.
Last Tuesday’s storm snow was capped with a robust but breakable and rough textured crust that is widespread across seemingly all aspects and elevations. This crust limits snow available for wind transport to that which has fallen since. Nine inches of snowfall since Tuesday has been subject to W and NW wind in excess of 100 mph. You’ll likely find mixed surface conditions of recently formed wind slab and exposed crust in the alpine. Be on the lookout for instabilities at the crust/wind slab interface and also between layers of recently formed wind slab. Snowfall is tapering off today though a few more inches could accumulate and be transported by the strong NW becoming W wind. A trend of clearing alternating with periods of snow showers is forecast for the coming days, with the next significant winter storm possible late next week.
Photo taken Thursday, November 17. Additional snowfall and wind loading has occurred since.
Continue to make thorough snowpack assessments and terrain decisions as winter conditions continue to take hold in our mountains. Respect small pockets of potentially unstable snow which have historically been the culprit of early season avalanche accidents on both ice climbs and larger snow slopes. In addition to avalanche hazards, be mindful of other early season hazards that exist in the terrain:
Rocks, trees and bushes lurk in the snow and in the fall line. Skiing or sliding into obstacles can ruin your day or worse. New snow may just barely cover a season ending stump or boulder.
Terrain traps and cliffs make burial and significant injury a real possibility, heightening the consequences of a fall or small avalanche.
Long sliding falls are a threat despite the appearance of new, soft snow on your approach. Wind can easily scour parts of your climb or hike down to a hard bed surface. What you thought would be a mellow snow climb can turn into something much more exciting. Don’t count on self-arrest to save you. Consider using a rope in third class terrain or sooner than normal due to the slick surface.
The summer Lion Head Trail remains a preferred east side route to the summit over the Tuckerman and Huntington Ravine Trails, though watch for our recommendation towards the Winter Route that will come with ad
Safe travel in avalanche terrain requires training and experience. This forecast is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
Avalanche danger may change when actual weather differs from the higher summits forecast.
For more information contact the US Forest Service Snow Rangers, AMC visitor services staff at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or seasonally at the Harvard Cabin (generally December 1 through March 31). The Mount Washington Ski Patrol is also available on spring weekends.
Posted 11/17/2018 at 7:00 AM.
Ryan Matz Snow Ranger
USDA Forest Service
White Mountain National Forest
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