Avalanche Advisory for Wednesday, December 31, 2014

This advisory expires tonight at 12:00 midnight. Happy New Year’s Eve, everyone!

All forecast areas of Tuckerman and Huntington Ravines have Low avalanche danger. Natural avalanches are very unlikely and human triggered avalanches are unlikely except in isolated terrain features. Unstable snow may exist in isolated terrain features – use caution in these locations.

AVALANCHE PROBLEM: Similar to yesterday, current avalanche problems are limited to small pockets of wind slab that developed early this week. There is a slight chance for enough snow to fall today that new wind slabs may develop in isolated areas, especially the well-protected leeward slopes in Tuckerman. In both ravines, the overall snowpack is looking rather sparse for the end of December. This means the locations where you may find unstable slab are relatively small and isolated from other areas of snow. This does not mean they are “safe” or that you should leave the beacon, shovel, and probe down in the car. In fact, given the consequences of a fall in the current conditions, any small pocket of unstable snow will be quite dangerous. On the whole, there is a lot of stable snow out there, but don’t let your guard down.

WEATHER: The cold weather has certainly settled in over the mountains. The summit of Mt. Washington has been below zero degrees F for about 40 hours now and may only go a few degrees above at some point tomorrow. A cold front will pass by this morning, providing a chance for some light snowfall accumulations of a trace – 2″ (tr-5cm). Winds will continue to be fairly strong, but may diminish somewhat after the front has passed by. Expect gusts up to 75mph (120kph) this morning. Once again, be prepared for arctic conditions above treeline. You may also face very limited visibility with clouds and blowing snow.

SNOWPACK: Throughout much of both ravines you will find snow with good to very good stability. Exposed crust and wind-packed hard slab are commonplace right now. Both of these surfaces can be very strong and make for good climbing conditions, and they can also make for very rapid descents if you were unable to quickly self-arrest a fall. There are two stability situations you should be watching out for. One is a slab resting on top of a layer of weak snow on top of crust. I saw this in one location beneath Pinnacle Buttress two days ago, and can envision other similar pockets existing elsewhere. The other is any new soft slabs created this morning from new snow and wind loading. I expect both of these to be limited in size and distribution. The true extent of the new slab problem will be determined by the amount of new snow received. If we reach or exceed the 2″ mark, this problem may push the boundaries of Low danger in favorable locations.

In other news, the Lion Head Summer Trail remains open and will be the preferred route until we get significantly more snow. The trail does cross an avalanche path in a couple locations, but there needs to be a lot more snow before this becomes a problem. The John Sherburne Ski Trail has fair coverage but is very hard-packed, icy, and very bumpy. And finally, we will be resuming the Eastern Snow and Avalanche Workshop (ESAW) Continuing Education Series this winter. The first session will be in mid-January. Stay tuned to our Facebook page for more details in the coming days.

Please Remember:

  • 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 7:30 a.m. December 31, 2014. 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