Avalanche Advisory for Thursday, March 17, 2016

All forecast areas of Tuckerman and Huntington Ravines may develop MODERATE avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Lobster Claw, the Lower Snowfields, and Little Headwall are not posted due to a lack of snow in these areas.

AVALANCHE PROBLEM: Today’s avalanche problem will require careful assessment of wind and weather conditions to sort out a safe travel plan. Two inches of new snow at higher elevations last night plus one to three inches more this afternoon may create a more serious avalanche problem than you might expect, considering the spring-like weather discussed below. Wind slabs may develop due to effective loading wind speeds and gusty thunderstorms this afternoon along with a remote potential for rain on snow which would create the potential for wet slabs or wet loose avalanches to develop. Poor air mixing, a degree of uncertainty on the part of weather forecasters, and the inherent challenges of precipitation forecasting lead us to have a high degree of uncertainty in our avalanche forecast for today. (Read more about this at NWS and MWObs websites.)  It is quite possible that we will stay in a Low rating today. Nothing deep in the snowpack is affecting our avalanche forecast so we will leave that for tomorrow or for the weekend advisories if new snow materializes.

WEATHER: Last night the summit recorded 2” (5cm) of snow with .35” (8mm) of water. Meanwhile, Hermit Lake recorded no snow, 2mm of ice on the board with 8.4mm of water in the can, mostly in the form of rain. Wintry temperatures will return to the mountain today, but not before elevation dependent snow, rain showers, and even thunderstorms move through the area. This afternoon, be prepared for periods of heavy snowfall or graupel along with gusty winds (to 70mph) and lightning should thunderstorms pop up over the range. Temperatures will fall from the current 26F into the lower-teens F after dark. West winds will increase from 35-50mph to 45-60mph this afternoon.

Given the elevation dependent nature of today’s potential new snow, you will continue to deal with the spring hazards in addition to any avalanche hazards that develop today.  These typical spring hazards include:

  • Long sliding falls – Crampons are highly recommended in steep terrain. Snowshoes and microspikes are no substitute. Spring weather brings variable snow surface conditions that change by the hour and by aspect. Arresting a fall on an icy 30+ degree slope is practically impossible.
  • Crevasses, moats and waterfall holes – Warm water flowing under the snow pack creates holes and thin spots in surface snow that are deep enough to injure or kill you. New snow can obscure the openings.
  • Falling ice – This one is unpredictable. The best thing you can do is reduce your exposure by limiting the time you spend downslope from frozen waterfalls. Falling ice chunks can move with surprising speed and follow unpredictable trajectories.

TRAILS INFO:

  • The Tuckerman Ravine Trail uphill from Pinkham to Hermit Lake is mostly wall-to-wall ice. Traction devices or crampons are necessary for reasonable travel on this trail.
  • The Lion Head Summer Trail is open. The winter route is now closed.
  • The Sherburne Trail is closed about 2/3 mile up from the parking lot. Please respect the closure by walking over to the Tucks trail at the rope to reduce erosion on the ski trail.

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 8:10a.m., Thursday, March 17, 2016. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2016-03-17