Avalanche Advisory for Saturday, February 11, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravine have MODERATE avalanche danger today. All forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully to identify features of concern. The only exception to this rating is the Little Headwall which has Low avalanche danger. Natural and human-triggered avalanches are unlikely there.

AVALANCHE PROBLEM: Wind Slab and Loose Dry avalanches are possible in many areas today. Though on the smaller side, these avalanches could entrain enough snow to cause problems especially in steeper terrain or above terrain traps, boulders or trees. Small, loose dry natural avalanches could occur in a few areas like Pinnacle Gully and Chute. The primary concern however will be the wind slab avalanches that will likely be easy to trigger due to the low density snow coupled with light winds. Look for these wind slabs in upper start zones in the lee of features sheltered from southwest wind. Terrain with a north facing component is likely to have the greatest wind slab problem so be particularly heads up in Hillman’s Highway, Left Gully, South and Odell Gullies.

WEATHER: Currently in Pinkham Notch and Hermit Lake, the snowfall rate leads us to believe that we will reach the forecast 2-4” of snow early on today with 2-3” on the ground in Pinkham that fell mostly last night and this morning. Currently, wind speeds are blowing on the summit in the mid-30’s mph with some gusts near 50mph. NWS forecast models indicate that wind will continue from the southwest through daylight hours and only begin to shift to the northwest near dark. Wind will slack off through the day settling at the 20’s mph this afternoon. Temperatures on the summit are currently -3F but will rise to the teens.

SNOWPACK: Beneath this new snow you’ll find firm snow along with a dense ice crust in steep terrain. The crust will be breakable in sheltered or treed areas but will support your weight in our steep, open terrain. Areas of firm wind slab will be the primary bed surface in most of our mid-slope terrain. These older wind slabs developed on high wind speeds from the northwest, are stubborn and will likely be resistant to triggering due to the new snow load today.  Where the ice crust is closer to the surface and less insulated by the new wind slabs, you may find some faceting and weakening of the crust, though again it is not likely to be a player in avalanche activity today. These factors coupled with low density snow and light winds lead us to our moderate rating today. Remember that small avalanches can still hurt you so mind your runouts, approach steep, sluff deposited areas cautiously and use all your weather and snowpack assessment skills to confirm or deny the hazard level.

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  8:00 a.m., Saturday, February 11, 2017. A new advisory will be issued tomorrow.

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

2017-02-11