This advisory expires at midnight.
All forecast areas of Huntington and Tuckerman Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Dangerous avalanche conditions exist. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. The exception to this is Little Headwall which has Low avalanche danger. Natural and human-triggered avalanches are unlikely.
AVALANCHE PROBLEM: The main avalanche concern today will be Wet Slab. If the weather forecast pans out and temperatures drop as slowly as predicted, avalanche danger will remain at this heightened level for most of the day as stabilization will be slow to occur. Limited visibility this morning revealed wet debris in Hillman’s Highway and some of the steeper gullies on the Boott Spur ridge. As some gullies appear to not have avalanched yesterday, these places without debris are of greatest concern. The snowpack may see an additional stresses today from possible snow and sleet as well as temperatures that are hovering around the freezing mark.
WEATHER: Steady snowfall, yesterday and overnight, delivered 7.4” (18.5cm) of snow at Hermit Lake and 8.6” (21.5cm) at the Summit. Around midnight, temperatures warmed enough to allow freezing rain and ice pellets to form. This morning, the top 1cm of snow is wet with cold dry snow beneath. Current temperatures on the mountain are around the freezing mark. With a slow moving low approaching the region, warm air will linger for the morning. An additional 1-3” of sleet and snow is expected today. Strong SW winds of 65-80mph will shift to the W and decrease to 50-70mph. Temperatures will begin to drop in the afternoon, maybe reaching single digits Fahrenheit by later tonight.
SNOWPACK: Yesterday, wind slab formed from 8” of snow and strong winds that came from multiple directions. It is likely that several locations saw avalanches during this time. Overnight, wind slab were covered with wet slab with the summit reporting six hours of ice pellets or freezing rain. Wet debris can be seen out of Hillman’s and is an obvious sign of instability. It is likely that last night and this morning a mix of newer wind slab and some older surface had to absorb the liquid, increasing the likelihood of natural activity. Additional loading today will come from a possible 1-3” of sleet and snow. There is the potential for melt water to find its way down to an ice crust and provide enough lubrication for a deeper slab to release. This should highlight the fact that even slopes that have avalanched still harbor instability. With this in mind, conservative decision-making will be crucial to safely navigate the dangerous avalanche conditions that exist.
- 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 8:50 a.m., Tuesday, February 7, 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