Avalanche Advisory for Sunday, February 5, 2017

This advisory expires at Midnight.

 

Huntington Ravine has MODERATE and LOW avalanche danger today. Central, Pinnacle, Odell, South, and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern North, Damnation and Yale Gully have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger today. Sluice, Lip, Center Bowl, Chute, Left Gully, Hillman’s Highway, and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern. Lobster Claw, Right Gully, and Little Headwall have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Wind Slab that has formed over the past week is becoming firmer due to sustained west winds. With 2” of new snow forecast later in the day along with increasing winds, instability will increase as the snow arrives. If traveling late in the day, be sure to evaluate terrain carefully and identify features of concern as wind slab will develop rapidly in steep areas due to strong winds. These same winds that are loading the steepest areas of our terrain with textured firm slab are also scouring the northern gullies in both Ravines. Areas with a Low rating today may contain unstable pockets around isolated terrain features.

WEATHER: Since the start of the month, the Summit has recorded 4.7” of light density snow that arrived on primarily strong west winds. A trace of snow fell yesterday with winds decreasing through the day and last night to the current W 55mph. Winds will remain steady until the afternoon when a low pressure system moves in bringing increased winds, clouds, and the potential for 2” of snow. Overnight, snow showers may continue with winds shifting to the NW and approaching the 100mph mark by daybreak tomorrow.

SNOWPACK: Our current snowpack is made of severely wind-affected snow. Areas of most concern today will be the steepest terrain in Tuckerman, wind loaded mid-elevation slopes, and underneath the ice pitches in Huntington like Central Gully. These terrain features will have areas of firm-textured wind slab sitting on top of softer wind slab underneath. This firmer wind slab will likely be thick and supportive. Identifying the edge of the slab or areas where this slab becomes thin and weak due to terrain features will be crucial to playing it safe today. Other areas in our terrain will have pockets of this same textured slab along with areas of scoured old surface. With such variability abounding, isolated terrain features will harbor pockets of unstable snow that can be avoided with careful terrain and snowpack evaluation.

The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.

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  8:20 a.m., Sunday, February 5, 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

2017-02-05