Avalanche Advisory for Friday, February 3, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE avalanche danger today. All forecast areas in Huntington have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully to identify features of concern.

 Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. Sluice, Lip, Center Bowl, and Chute currently have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, Right and Left Gullies, Hillmans Highway and Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible.  The only exception to this rating is the Little Headwall which has Low avalanche danger. Natural and human-triggered avalanches are unlikely there. Open water and water ice remain exposed in the Little Headwall and the creek above. It is skiable but people have been occasionally punching through into water beneath.

Avalanche danger will be decreasing through the day as winds diminish and snow stabilizes over time.

AVALANCHE PROBLEM: Wind slabs which developed yesterday, and to a more limited extent overnight, will be your primary concern. Wind speeds and direction have been favorable for developing firmer wind slabs which fall well into the possible category on the scale of human-triggerability. You will likely encounter smaller softer slabs in wind protected pockets. Also, be on the lookout for firmer, more stubborn and larger slabs beneath steep pitches of ice. Due to diminishing wind speeds and not much snow available to be transported into our start zones, it is unlikely that we will see a natural avalanche today, but it remains possible for a skier or climber to be the added load that triggers a slab.

WEATHER: Another 1.2” of snow was recorded on the summit, with 1.5” at Hermit Lake, in the past 24 hours with peak snowfall occurring yesterday morning. During the day, winds shifted a bit to the WNW from the steady westerly direction of the past several days. These west winds were transporting snow from the previous 24 hour period when winds were lighter. This snow was primarily deposited into our strongest east facing aspects from our most loaded fetch zones in the alpine and cross-loaded into other aspects. Visibility will be challenged by summit fog down to Ravine elevations, though windows of clearing may open at times.

SNOWPACK: Multiple wind slab layers exist across our terrain without significant weak layers other than smooth interfaces marking wind shifts, subtle density or particle size changes. These wind slabs often prove to be pretty stubborn but due to their size and the uncertainty of their response to a human load, particularly on the steeper terrain, some of the travel advice associated with a considerable rating seems appropriate. Careful snowpack evaluation, cautious route finding and conservative decision making are essential. Field time yesterday occurred during peak snowfall and wind transport so gathering much useful data was limited to ruling out debris below the Lip and out into the floor. Pockets of soft slab were scattered around the terrain which is what you would expect under the prevailing conditions. In Huntington Ravine, Odell, South and Escape Hatch have well developed avalanche paths due to loading during several snowstorms this season with strong winds from the south. These gullies, plus Central and Pinnacle have a danger rating nudging into the higher end of the Moderate danger rating due to recent loading and potential size of the resulting avalanche. Be cautious when entering and travelling in these gullies.

Expect plenty of other climbers in the mountains this weekend and possibly today as the Mount Washington Valley Ice Fest brings folks into the area to enjoy the festivities. Be aware of other parties above and below you in steep terrain.

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., Friday, February 3, 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