This advisory expires tonight at 12:00 midnight.
Tuckerman and Huntington Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Dangerous avalanche conditions exist in our forecast areas.
AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem today. Avalanche danger will be elevated throughout most aspects of our forecast areas, with slopes facing east and north holding more danger than those facing primarily to the south (e.g. Lobster Claw or North Gully). We are starting today with dangerous avalanche conditions, and today’s weather will only continue adding to the existing stability problems.
WEATHER: Currently at Hermit Lake, it is snowing and blowing with very limited visibility; there are approximately 5″ (12.5cm) of new snow on top of the most recent crust. Pinkham Notch was warm with very little new snow on the ground, and the Mt. Washington Observatory is reporting 7.6″ (19cm) since Friday. We believe they may have even gotten a little more than that. As you can see, elevation has played a prominent role in total snowfall amounts, so your own weather observations need to be put into this context to be relevant to your stability analysis today.
Wind speeds will drop today, but not far enough to erase further wind loading as a concern from our minds. In fact, the NW 45-60mph (72-97kph) speeds forecasted are just about right for new slab development across much of the avalanche terrain in Tuckerman and Huntington. In addition to whatever recent snow is still available in the alpine zone for the winds to pick up, forecasts are calling for up to 3″ (7.5″)of additional snow today. Keep in mind that the past two days we have exceeded the forecast snow totals. If we get heavier snowfall this afternoon than some forecasts predict, we may see more than 3″ (7.5cm).
SNOWPACK: I wish I could give you a clear first hand account of what the snowpack looks like right now, but the reality is that I can only speculate. We believe avalanche activity has already occurred in some areas, but we can’t say when, how big, or even where exactly. The answers to these questions would provide a lot of information, but really you don’t need them to understand today’s avalanche problem . New snow and wind loading are causing avalanche danger to stay in the Considerable range. As you look at the snowpack anywhere on the mountain, you’ll find the crust created from the rain event on Feb 16-17. This layer is a good benchmark to keep an eye on as new snow continues to build over this crust layer.
The Sherburne has gotten better, particularly at the top. But down low near Pinkham not much new snow has fallen, so it’s still pretty grim down there.
- 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., February 21, 2016. A new advisory will be issued tomorrow.
Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856