Avalanche Advisory for Saturday, February 4, 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.

AVALANCHE PROBLEM: Steady snow showers and strong west winds over the past several days have created Wind Slab, a trend that will continue today. Avalanche danger will stay steady today as conditions will not favor stabilization nor increasing instability. Moderate rated areas on the south side of both ravines contain a good amount of snow and should be heeded with care; evaluate snow and terrain carefully. Right Gully and Lobster Claw have seen some scouring in the upper reaches during the steady upslope snow since the start of the month and will offer easier safe passage than other gullies with a similar rating.

WEATHER: Since Tuesday, upslope snow showers brought between 0.6” to 2.4” of snow each day. West winds averaged around 55mph, maxing out close to 90mph. Last night, winds shifted slightly to the WNW and have remained steady above 70mph since 4am this morning. Today, upslope snow will bring up to another 1” of snow as winds slowly work back to the W and decrease to around 50mph at day’s end. Approaching high pressure may allow for a period of clearing tonight and early tomorrow morning.

SNOWPACK: Multi-layered wind slab is the predominant snow surface around our terrain. Density changes in the slab were the weak interface yesterday, caused by changes in wind speed and direction. Four finger (4F) slab was showing small cracks, but no further propagation. New slab depth was 30-50cm deep in the Fan of Huntington with deeper pockets likely existing below steep terrain. With a slight shift in wind direction and increase in wind speed last night, expect this slab to become firmer. While perhaps just creating another weak interface, pockets of the 4F slab will survive and may provide a weak layer for the developing firmer (one-finger, 1F, and pencil, P) wind slab on top. These pockets will be prevalent in the steepest terrain such as the Sluice through Chute in Tuckerman as well as below terrain features like the start of ice climbs in Huntington.

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  8:10 a.m., Saturday, February 4, 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

2017-02-04