Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely in all forecast areas. Watch for unstable snow on isolated terrain features.
AVALANCHE PROBLEM: Today’s avalanche problem will be loose wet slides. These will primarily be skier triggered and while slow moving, they can be tough to escape once entrained. These can be triggered anywhere, but will be a bigger problem in areas that have not seen traffic recently as there is more loose snow available. Wet Slab avalanches are unlikely. Our snowpack has had several days to adjust to the warm temperatures, but with possible record-setting temperatures today combined with more than half an inch of rain tonight, we may see a deep layer lubricate enough to release. This would be most likely in an area that already has water running through it. The waterfall hole in the Lip is an area that potentially could burst open and cause a deep slab release with the right conditions.
WEATHER: Currently, the temperature on the Summit is 37F with a SW wind at 35mph. Hermit Lake is at 46F. Temperatures may increase slightly through the afternoon before falling significantly tonight, reaching close to single digits F by daybreak tomorrow. Occasional rain may fall today, but it seems that most of the rain will fall after dark, with up to ¾” of water, before changing over to snow. With plenty of moisture in the air, most of the terrain will likely remain in the fog today.
SPRING HAZARDS: Our snowpack has been warming for over 72 hours. Springtime hazards are emerging and will likely play a larger role than the avalanche hazard today. Pay particular attention to
Ice and Rock fall: Several ice climbs in the valley collapsed during the warm spell. Higher elevations are heading this way. Be aware of what hangs above when traveling around the mountain, particularly in the Lunch Rocks area.
Undermined Snow: Runoff is raging at the moment with flood warnings issued through tomorrow. Areas like the Little Headwall and other rivers are eating away at the snow from beneath. New holes are opening constantly in streambeds.
Glide Cracks and Crevasses: The snowpack is slowly moving downhill and pulling away from cliffs and rocks, creating holes in the snowpack. With heavy fog today, these may be difficult to see.
Ice Dams: Lots of water is flowing today. The pressure that this can create when dammed behind an ice flow can cause things to burst naturally or from an ice tool placement
Long Sliding Falls: Unlikely today, these will be the main hazard tomorrow. With the temperatures plummeting tonight, expect the snowpack to freeze into concrete. If recreating tomorrow, make sure your crampon and ice axe skills are sharp.
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 8:05 a.m., Saturday, February 25, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856