Avalanche Advisory for Sunday 1-29-2012

Expires 12:00 midnight, 1-29-2012

Tuckerman Ravine has Considerable and Moderate avalanche danger. The Lip and Center Bowl have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. 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 warranted.

Huntington Ravine has Moderate and Low avalanche danger. Central, Pinnacle, Odell, and South gullies have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. North, Damnation, Yale, and the Escape Hatch have Low avalanche danger. Natural avalanches and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

After a great field day Saturday with lots of interesting observations, Mt. Washington pulled an ace out of its sleeve last night and once again left me recalibrating to a new set of information. About an inch (2+cm) of new light density snow fell on the mountain overnight and W winds have been blowing snow above treeline since 3pm yesterday. Winds have been ideal for loading this new snow into soft slabs in protected lee areas, i.e. they were from the west at 60-80mph (97-129kph) since midnight. The total amount of snow may be small, but with winds like these and light density snow I can’t rule out the possibility for natural avalanche activity today. The areas of greatest concern in Tuckerman are the Lip and Center Bowl. In other areas I expect new soft slabs to be developing throughout the ongoing wind loading situation. While the chances for natural avalanches to occur in these Moderate-rated areas are less than in the Lip and Bowl, the potential for a person to be the trigger puts them into the Moderate realm. Right, Left, and Hillman’s will offer the most stable route-finding options, but care should be taken when traveling in newly deposited slabs. Potential bed surfaces included crust developed after Friday’s warm weather and smooth windslabs that were built in many lee areas by another small snowfall around 9-10pm Friday. Tuckerman has a highly variable snowpack with some interesting layering taking place. It wouldn’t be a big surprise for a small avalanche to step down into deeper layers, the consequences of this happening to a person would be severe.

Huntington has similar issues today with new snow building into fresh slabs, but it has a slightly different bed surface history. Whereas in Tuckerman the lee areas were protected enough to build a foot or more of windslab on top of the wet layer, Huntington was more scoured down. For this reason, the primary concern in Huntington is the new snow deposition from last night and through today. You can find the deepest areas of this at the tops of the approaches to the ice, particularly in Central and Pinnacle. Below Harvard Bulge and Yale slabs is another area to watch out for. There are also newly loaded pockets in some of the upper sections of the gullies you might want to avoid. When possible, stay on the older snow to avoid this issue.

The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk.

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 8:50am. 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

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