This advisory expires at Midnight.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Yale, Central, Pinnacle, and Odell have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. North, Damnation, South and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. Sluice, Lip, Center Bowl, Chute, Left and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw and Right Gully have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.
Dangerous avalanche conditions exist today. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential in avalanche terrain.
AVALANCHE PROBLEM: Wind slabs developing in avalanche terrain are likely to be touchy today as the wind loads snow into the terrain. These wind slabs will develop over soft and weak snow which fell yesterday. To add to the danger today, our unstable snow rests on a very hard, refrozen snowpack. The firmness of this snowpack coupled with the many boulders and small cliffs that remain uncovered in the avalanche paths would make a fast and unpleasant trip if caught in an avalanche. Expect medium sized avalanches in Considerable rated areas that are capable of burying a person despite only 4.6” of new snowfall in the past 36 hours.
WEATHER: The increasing wind speed is the primary information to inform any travel decisions in avalanche terrain. In the past 24 hours, the summit recorded 2 inches of new snow with 4.6” total in the past 36 hours. During that same timeframe, winds from the SSE blew at just 20-30 mph. This morning the wind jumped up to the 50 mph (88 kph) range at around 7am and has shifted to its current position from the WNW. Currently, visibility is limited to a couple hundred yards due to dense fog and blowing snow. This morning will be a challenging time to make assessments of active loading but with the current wind speed and direction you can assume that the snow that fell in the past 36 hours is being moved into start zones of leeward slide paths.
SNOWPACK: Despite low wind speeds yesterday, snow was deposited and scoured to some extent. This means that we can expect some larger and more consequential wind slabs to exist in certain areas. Typically, wind speeds between 20-50 mph move snow into the mid to upper sections of most of our terrain. Due to shifted wind direction, you can expect to find wind slabs in a variety of locations. Also, this wind shift will access snow previously sheltered by lighter, southerly winds. The increased wind speed will also create more cohesive slabs that could be triggered by a person. Be cautious in any of our avalanche terrain today since sensitive wind slabs are likely to exist in one size or another in any area.
- Safe travel in avalanche terrain requires training and experience. This advisory 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.
- Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
- For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
- Posted 8:30a.m., Thursday, January 19, 2017. A new advisory will be issued tomorrow.
Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713