Avalanche Advisory for Tuesday, March 4, 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 avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely in these areas.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has 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 in these areas.

AVALANCHE PROBLEMS: Once again, wind slab is the primary avalanche problem. The most widespread wind slab problems can be found in the Sluice through the Chute of Tuckerman. Elsewhere, such as Left Gully and Hillman’s, you’ll find more hard wind slabs interspersed with areas of relatively softer slab and areas with wind affected snow. Huntington has been more affected by winds, almost to the point that it would be better described as scouring. There are areas of hard slab here as well, which leads into the secondary avalanche problem of persistent slabs. See below for more detail on this problem.

WEATHER: Despite the news headlines about the blast of arctic air that was supposed to invade last night, it really doesn’t feel much colder than it has all winter long. Where I sit writing at Hermit Lake it is a balmy +5F (-15C), but the lack of strong winds and bright sunshine makes it feel a little nicer than that. During the daylight hours, you should expect increasing clouds and the possibility of light snow shower activity late today. There are no significant storms threatening us for the next several days at least.

SNOWPACK: Remember back in February when we got that freezing rain crust? Well, that crust has begun to break down. As this happens, the crust loses both tensile and compressive strength. When it comes to weak layers, in my opinion the loss of compressive strength is the more worrisome component. The faceting that is beginning to happen around this crust makes for a weak layer that is prone to collapse, and since weak layer collapse is the first event in the process of an avalanche releasing, this is an important feature of the snowpack that we’ll be keeping an eye on (and you should be looking at, as well.)  This won’t be a big deal in places where there is no snow above the crust, i.e. the crust is the surface layer or very close to the surface. Where it comes into play are locations where wind slabs sit above the crust. This may be “triggerable” in places where hard slabs are thinner or in places where the slabs are relatively softer. The older, harder slabs are the ones I would describe as “persistent,” while the more recent softer slabs fall into the wind slab problem definition. Also, as mentioned in yesterday’s advisory, above the crust there is an interface between two layers that has shown some signs of instability as well. Keep an eye out for this as you do your assessments in the field today.

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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
  • Posted 8:10a.m. 03-04-2014. 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

2014-03-04 Print friendly

And since you read down this far, here are some photos from Huntington this morning…

2014-03-04 Hillman's 2014-03-04 Escape Hatch 2014-03-04 Yale and Damnation 2014-03-04 Central Gully 2014-03-04 Odell Gully