Avalanche Advisory for Friday, February 24, 2017

This advisory expires at Midnight.

Huntington Ravine and Tuckerman Ravine have LOW avalanche danger. Natural and human-triggered avalanches are unlikely.

 AVALANCHE PROBLEM: Skier triggered wet-loose avalanches will be the primary avalanche problem today though other emerging spring hazards will pose an equal or greater danger. Loose but heavy sluffs of snow kicked up by a skier can be challenging to deal with at times so be mindful of this hazard, especially if venturing into areas with a sunny aspect or an area that’s not been ridden recently. Though the prolonged heat wave has generally allowed weaker layers in our snowpack to settle and bond, wet slab avalanches are a greater possibility today as water travels deeper into the snowpack. The Lip waterfall often flows onto an ice layer within the snowpack resulting in a wet slab avalanche during early spring thaws with rain. Today’s record warmth and rain in the afternoon will increase the potential for this sort of avalanche activity in our forecast area.

WEATHER: Continued warm temperatures last night did not refreeze the snow at our forecast elevation. Temperatures will continue to rise from where they stand at 32F on the summit and 46F at Hermit Lake, ultimately reaching 40F on the summit. Partly cloudy skies this morning will give way to more clouds as a warm front arrives around noon. NWS forecast models are calling for up to a ¼” of rain this afternoon which will only add to the melt water flowing in the snowpack due to warm air temperatures. Southwest wind will diminish a bit to 30-45mph before increasing again to 50-70 mph as the warm front arrives in the afternoon.

SPRING HAZARDS: Sloppy wet cement was one description I heard for the snow yesterday. Without a freeze last night, similar conditions will prevail today with firm surfaces in some areas. Due to the late arrival of our typical January thaw or early taste of spring, the following hazards should begin to appear on your radar.

  • Ice dams – water flowing down Huntington gullies can build up pressure behind ice and burst.
  • Glide cracks, moats and crevasses are beginning to open a bit and may grow larger as things warm.
  • Falling ice and rocks become more frequent and sometimes larger as bonds holding things in place release.
  • Undermined snow over stream channels can be a problem in gullies but more of a danger lower in the tributaries. The generally warm winter so far hasn’t allowed many streams to freeze so this undermining is likely to emerge early this year. The waterfall has re-emerged in the Little Headwall, along with the rocks until recently covered in ice, and is indicative of this problem.

Eight days ago, there was 94” of snow at the Hermit Lake snowplot with 75” this morning. Though we still have really good coverage, expect one more warm day tomorrow with up to an inch of rain before freeze up on Sunday.

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  8:03 a.m., Friday, February 24, 2017. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856