Avalanche Advisory for Saturday, February 1, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, South, and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely.

AVALANCHE PROBLEMS: Persistent slab is the primary concern for the better part of the day. New snow late in the day will create additional wind slab problems, but it’s unlikely that this will develop much during this forecast period. The persistent slab problem has been nagging us for some time now, and our time in the field assessing conditions has consistently confirmed that the possibility exists for a person to trigger an avalanche in many locations. The snowpack will feel strong under your feet, but be aware that weaknesses exist in the strong slab. You can very quickly and in short distance move from strong stable snow to a spot with a greater likelihood of you triggering a slide.

WEATHER: Pull out the fat skis, it’s going to be deep tonight! Just kidding, we are expecting snow to arrive late today, but not enough to make me feel like we’re pulling out of the drought from the last two weeks. In case you’re wondering, the snow at Hermit Lake was 59cm deep on January 1st; today it sits at 57cm. So with that in mind, a 2-4″ (5-10cm) snowfall overnight is reason enough for a Celebration!

If you’re on the mountain today, expect worsening conditions above treeline this afternoon and evening. The onset of snowfall will coincide with increasing wind speeds and lowering cloud levels. This will make visibility challenging. Pay attention while the weather is good on your way up so that you can more easily stick to your intended route on the descent.

SNOWPACK: Traveling in avalanche terrain you’ll find a lot of snow that has good stability, but as mentioned above, you will need to be alert to the potential for weak points that could cause you to trigger an avalanche. Generally speaking, the problem is being caused by a very weak layer just above the Jan 11 rain crust. On top of the weak faceted layer, there are hard slabs that are quite brittle and capable of propagating a crack. Areas with a northerly aspect, e.g. Left Gully or South Gully, have slabs that are slightly less hard, and therefore would be easier for your impact to punch through to the weakness. The left side of the Center Bowl is another area of concern. This location between the Chute and the crown line from earlier this week is an area where you’ll find the facets under slab problem. Most areas posted at Low danger have very little snow in them.

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 8:00am February 1, 2014. A new advisory will be issued tomorrow.

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

2014-02-01 Print friendly