Avalanche Advisory for Saturday, February 8, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low 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 danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, and Yale have Low danger. Natural and human triggered avalanches are unlikely. In these locations, watch for unstable snow in isolated terrain features.

AVALANCHE PROBLEMS: Wind slabs have been the dominant avalanche problem for the last few days. Today is the same. These were formed during Wednesday’s storm and saw further development in the last 30 hours or so. These can be found in most forecast areas of both ravines, though in some you’ll find much more widespread problems than in others. For example, the northern gullies of Huntington have Low danger, but you can find pockets of wind slab at the top of each of the gullies, near the ridge. In these location, you can largely avoid the problem with route finding and good avalanche awareness. In Central Gully, you’ll have a much more difficult time avoiding areas with unstable snow, due to the extent of the wind loading that took place here.

WEATHER: It’s a cold morning up on Mt. Washington, temperatures are below zero F (-18C) from about 4000′ elevation up to the summit. Winds will remain strong enough to keep you honest, blowing in the 50-60mph range for most of the day (80-97kph). We do not expect to see any new snowfall until Sunday night or early Monday morning, but blowing snow and thin clouds may make visibility challenging today.

On Wednesday we received 10-12″ of snow across the mountain. This bumped avalanche danger during the storm and caused a small avalanche cycle. There was a lull in the winds on Thursday, but as velocities ramped up in the overnight hours, snow began to get moved around again. Since early in the morning Friday, the Observatory has recorded blowing snow in all but a few hourly observations. Currently this is causing frequent spindrifts and snow devils, but is only adding limited new load to the snowpack.

SNOWPACK: Yet again, it would be difficult to generalize what is going on with our snowpack due to intense spatial variability. The key layers you should be focused on are the wind slabs that have recently been developed. There is still a lingering concern about a faceted weak layer, but this plays second fiddle for two reasons. First, the wind slab is the one you’re more likely to trigger. Second, the distribution of the faceted layer is uneven throughout the terrain, offering the chance for false stable stability evaluations if you test in the wrong area. So again, focus your attention on the uppermost layer of wind slab. Winds during the time frame we’re looking at were mostly from the WNW, so the greatest loading has taken place on E aspects, though to a lesser degree cross loading has occurred in areas with both northerly and southerly components to 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 8:20 a.m. 2-8-2014. 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

2014-02-08 Print Friendly