Avalanche Advisory for Tuesday, February 25, 2014

This advisory expires at 12:00 midnight.

Tuckerman Ravine has Moderate avalanche danger in all forecast areas. Natural avalanches are unlikely and human triggered avalanches are possible. The only exception to this rating is the Little Headwall, which has Low avalanche danger. Natural and human triggered avalanches are unlikely in this area.

Huntington Ravine has Moderate and Low avalanche danger. Central Gully has 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 except in isolated terrain features.

AVALANCHE PROBLEMS: Be on the lookout for new wind slab sitting on top of last weekend’s rain crust today. You’ll find this in areas that are strongly protected from westerly winds, such as the Lip and Center Bowl in Tuckerman and Central Gully in Huntington. You’ll also find it in isolated areas around most other forecast areas. Whether you’re in an area rated Moderate or Low, any snow sitting on top of the crust should be seen as potentially unstable. The biggest problems are where larger amounts of snow have been able to collect, whether through wind loading (e.g. in the Lip and Center Bowl) or through deeper pools of sluffs at the transitions from steep terrain to less steep (e.g. on ice routes in Huntington or below the narrows of the Chute.)

WEATHER: You know it’s a cold morning when Joe starts talking about Earnest Shackleton and how thankful we should be to not need to heat the cabin with seal blubber. Currently temperatures at Hermit Lake are hovering in the zero F range (-18C) and while summit winds have diminished into the 30-45mph (48-72kph) range it still feels like they have the ability to suck the heat from you quicker than your body can generate it. Expect a cold day with some clouds and a chance of light snowfall. Yesterday snowfall totals at the summit were 1.5″, though it only a trace landed at Hermit Lake. Maybe it’s just been blown over to Wildcat? There are no major storms on the horizon for us, but we might get smaller snowfalls throughout the upcoming week.

SNOWPACK: The dominant feature in the snowpack remains the freezing rain crust. Your primary concern should be focused on what sits on top of the crust. Where you encounter new snow above the crust, it will be a mix of older snow from late Friday and new snow from last night. The deeper the snow on top of the crust, the more suspicious you should be of it. Beneath the crust there are also some potential weaknesses, but these will be harder for you to trigger. The most likely scenario for these to come into play would be in an area with a large unstable slab sitting on top of the crust. Generally, the crust has a lot of tensile strength and is limiting the ability of any underlying slab to propagate a crack. In the situation where a large slab has buried the crust, the load could be more than the crust can handle, resulting in a large avalanche stepping down into deeper layers.

Please remember:

  • Safe travel in avalanche terrain requires training and experience. This advisory is 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 USFS Snow Rangers, the AMC at the Pinkham Notch Visitors Center, or the caretakers at Hermit Lake or the Harvard Cabin
  • Posted 8:20a.m., February 25, 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

2014-02-25 Printable