Avalanche Advisory for Tuesday, January 13, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, and Chute 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, although unstable snow in isolated terrain features may exist.

Huntington Ravine has Moderate and Low avalanche danger. North Gully, Damnation, Yale, Central, and Pinnacle have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Odell Gully, South, and Escape Hatch have Low avalanche danger. Natural and human-triggered avalanches are unlikely, although unstable snow in isolated terrain features may exist.

AVALANCHE PROBLEM: Recently formed wind slabs are the problem to watch for today. These developed in the previous 24 hours and are still receiving some additional deposition from the cascades of low drifting snow blowing in from the alpine zones. I don’t expect the blowing snow to contribute much in addition to existing instability, so what’s on the ground now is what you’ll be dealing with through the day and likely beyond. The locations where you are most likely to encounter snow instabilities are in the Lip in Tuckerman and Yale Gully in Huntington.

WEATHER: Today is starting cold and sunny. Temperatures may not rebound much from their position in the single digits Fahrenheit, but winds are expected to decrease to a modest 20-35mph (32-56kph) and shift from N to NW. Yesterday there was light snow throughout the day, leaving 4” (10cm) or so on the summit. Lower elevations did not record quite as much new snow. There are no significant precipitation events in the coming days.

SNOWPACK: Generally good visibility this morning is allowing for visual assessments of the snow surfaces after yesterday’s weather event. Some of this snow is currently airborne, with clouds of cold smoke drifting across the mountain and down into ravines. The 4” of snow that fell yesterday with NW winds in the 60mph range doesn’t appear to have made much of a difference in snow coverage. The visual clues do indicate there has been some snow loading, but there also appears to be locations where winds have not allowed new slab to develop. The most concerning locations have a smooth surface indicative of new wind slab. While these are not widespread, they may be tender and reactive to triggering. Be watchful for pockets of this even in areas rated Low, such as Odell or Right Gully. A highly textured surface in many areas has me wondering if I’m seeing newly developed and wind-affected slabs, or am I seeing older surfaces with a veneer of bright new snow. You don’t need to read between the lines here. I’ll tell you that I have a lower-than-usual level of confidence in the visual assessments this morning, despite the good visibility. While I suspect good stability in a lot of these textured surfaces, I encourage you to treat them as if they are less stable until you can prove otherwise.

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 8:45 a.m. January 13, 2015. 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

2015-01-13