Avalanche Advisory for Tuesday January 21, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, and Hillman’s Highway have Moderate 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 except in isolated terrain features.

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. North, Damnation, and Yale gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.

AVALANCHE PROBLEMS: I am mostly concerned about human triggered avalanches today. These will be possible on slopes with recently formed wind slabs. Areas posted at Moderate have larger areas of new wind slab; areas posted at Low danger may also have unstable wind slab, though they are smaller and more isolated throughout the route. Cold weather is limiting the ability of these slabs to stabilize.

WEATHER: Before committing to your plan today, take a quick look at the temperatures that are forecast. While we’re a long way from as cold as it gets, temps today are certainly in the range of “let’s not stand still too long.” Clouds will be moving in, as well as the possibility of some light snowfall this afternoon. The best part of today’s weather is that the wind speeds will be diminishing to manageable levels.

The avalanche problems you’ll be facing today are a result of recent weather history, more so than today’s incoming weather. Over the last 3 days, Hermit Lake has received 4” (10cm) of new snow. In the last 48 hours this was blown about from predominantly westerly winds, with gusts as high as 95mph (153kph) during this time.

SNOWPACK: There is a lot of spatial variability out there today. This common characteristic shouldn’t surprise regular readers of the advisory. We can go back to the most recent snowpack-resetting rain event on Jan 11. Since then there has been regular light snowfall, but no major storms. The way the winds have redistributed the recent snow, in many locations you’ll find an upside down quality to the slabs. The strong-over-weak  setup results from increasing wind speeds during and after a storm. This took place on Sunday night and in some areas there will be softer slab on top of the upside down feature.

In some locations, you’ll find a strongly wind-effected snow surface or even some old crust. Examples would be Left Gully and the climber’s left side of Hillman’s. These areas generally have good stability, but if you get into “isolated terrain features,” i.e. those locations well protected from strong winds, you can expect to see some areas of instability. In Huntington, the avalanche starting zones in the northern gullies have scant snow coverage, but where there is snow you should be on the lookout for instabilities. Good route-finding in these gullies will go a long way to keeping you out of harm’s way.

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 8:10a.m. Tuesday, January 21, 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

2014-01-21 Print Friendly