Huntington and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely. In Tuckerman Ravine, Little Headwall and Lower Snowfields are not forecast due to thin snow cover.
AVALANCHE PROBLEM: Water in the snowpack appears to be refrozen at most elevations and aspects on the mountain. As a result of this refreeze, the probability of Loose-Wet and Wet Slab avalanches will continue to decrease. One factor that is hard to pin down is the cloud cover forecast. On sunny aspects, the refreeze may slow or even reverse; be vigilant about snowpack evaluation as you venture onto steeper sunny slopes later today. No evidence of wet slab avalanches exist from yesterday which points to a generally settled and well-bonded snowpack, but wet-loose debris points to the continued need for terrain and sluff management. As the breakable crust thickens, expect travel conditions to be challenging due to postholing .
WEATHER: Yesterday’s warm front lingered around the area for most of the day. High pressure finally moved in this morning just before dawn, shifting winds to the NE and allowing temperatures to drop from the mid to high 20sF into the teens. This high pressure and an inversion will keep summit skies clear for part of the morning before a coastal low pressure system arrives. Clouds may develop this morning with summits possibly becoming clouded by the afternoon. Temperatures should remain in the teens through the day with winds shifting to the east and increasing to 40mph by the end of the day. We may see snowflakes in the air today, but the meat of the approaching storm will begin overnight. We likely will have a few inches on the ground by sunrise tomorrow.
SNOWPACK: After about 80 hours with temperatures staying above 20F on the summit and at times rising above freezing, we are seeing a return of colder air. This extended period of near freezing temperatures combined with periods of calm winds and clear skies allowed our snowpack to warm and about the top 30cm of snow to become wet. As this wet snow freezes, expect the current surface crust layer to become thicker and more supportive. Be particularly aware of sluff and terrain management on sunny aspects if skies stay clear as the day progresses. As the freezing process takes place, this will become a shin scraping crust and eventually a supportive surface, though this may not happen until after dark if temperatures stay in in the high teens and low 20sF as forecast.
The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.
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 8:15a.m., Monday, January 23, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713