Huntington and Tuckerman Ravine will have LOW avalanche danger today. Generally safe avalanche conditions exist for all forecast areas.
AVALANCHE PROBLEM: The warm and moist conditions of the weekend are gone and the layers of instability are gaining strength. The crust forming on our snow surface, and your ease of travel on it, will vary through the terrain. You will probably find both supportable and breakable crust surface conditions. These variable conditions, which will include hard, refrozen snow, could allow a long sliding fall and will likely be a greater concern to you than avalanches. Crampons, ice axe, and your ability to use them effectively will be necessary tools above tree line. Microspikes are no substitution but will be a useful tool on hard packed trails at lower elevations.
WEATHER: The Summit of Mount Washington reached a high of 36F yesterday in the late evening with a trace of snow and a total water equivalent of 0.11”, largely coming in the form of freezing rain in the afternoon. As high pressure built in from the west overnight, temperatures began to plummet, with temperatures at 7am reading 9F at the Summit and the high teens at Hermit Lake. Wind speeds reached 80mph from the west at midnight, and will increase slightly to the century mark and shift to the NW today. Snow flurries may appear this morning, giving way to clearing skies as the day progresses.
SNOWPACK: Our upper snowpack is currently refreezing following the recent above freezing temperatures and wet precipitation. Around Hermit Lake, the crust forming is currently one inch thick and breakable. Prior to the warm conditions which began midday Saturday, our surface snow was a mix of soft and hard wind slab with scattered areas of exposed January melt-freeze crust. Stability concerns of these layers are becoming minimal with the refreeze. These varied surface conditions will reflect today in the form of a crust that will likely be breakable in previously soft areas and supportable in previously hard areas. Expect a mixed bag of travel techniques to be necessary. Long sliding falls should be on your mind today; consider breaking your rope for third and fourth class terrain. Realize that areas with a crust breakable under your boots might easily support the weight of a sliding human body.
• 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 Harvard Cabin.
• Posted 7:20 a.m., Monday, February 12, 2018. A new advisory will be issued tomorrow.
Helon Hoffer / Ryan Matz, Snow Rangers
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856