Avalanche Advisory for Tuesday, 1-17-2012

This advisory expires tonight at midnight.

All forecasted areas of Tuckerman Ravine will have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. The only exception to this is Right Gully which has Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated pockets. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when conditions warrant.

Huntington Ravine will have Considerable and Moderate avalanche danger. North and Damnation Gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas will have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely.

Incoming weather later today is driving today’s forecasted ratings, so it’ll be a good day to get an early start and to not be out after dark in the ravines. Another weather system reminiscent of December is coming, beginning with snow through the afternoon, then warm temperatures will change this over to sleet before the day is done. Rain will eventually fall in valley locations since temperatures will be above freezing. I don’t know about you, but this is enough to make me want to bang my head off the wall a few times. With any luck, the bulk of the precipitation here will be in the form of snow. The forecasted total of 2-4” (5-10cm) will be very dependent on when the warm air is able to gain the upper hand. With SW winds in the 25-40+mph range (40-65kph), the early snow will load into soft slabs in the upper portions of many areas, notably those with a N or NE aspect. Areas with an E aspect will see some cross-loading as well (e.g. the Center Bowl and Lip or Central and Yale). The potential for sleet falling onto newly developed softer slabs creates the possibility of naturally triggered avalanches. Similarly, if you find yourself plodding your way through new soft snow near the gully tops, you might want to start thinking about finding older snow to climb on.

Today’s weather forecast is a tricky one. There is a good chance that for the better part of today not much snow will fall. So until snow is able to accumulate, the danger level will be less than the forecasted ratings. We spent a lot of time in Tuckerman yesterday and found an interesting variety of conditions. In all areas from the Chute to the Sluice, we found an upper layer of hard windslab sitting on top of lighter density layers. In the thickest locations the slab had a lot of strength, but where it was thinnest near the edges there was a noticeable weak layer and lots of elastic energy. Overall the ravine still has typical early season snow coverage and is very much broken up by ice slabs, rocks, and small terrain features. If you’re out in Tuckerman early today before snow falls, you should be expecting fair to good stability with some locations being slightly worse. It changes quickly as you move around so stay alert.

Tonight the mountain will rage once more. Winds are expected to easily exceed 100mph while temperatures freefall into the negative numbers Fahrenheit. Wednesday will be another blustery arctic day, making above treeline travel very challenging.

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 8:10am. 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

2012-01-17 Print friendly