Avalanche Advisory for Saturday, March 4, 2017

This advisory expires at Midnight.

Huntington and Tuckerman Ravines have LOW avalanche danger. All forecast areas have Low avalanche danger. Natural and human-triggered avalanches are unlikely. The Little Headwall is not forecast due to lack of snow.

AVALANCHE PROBLEM: Just over three inches (3”) of snow arrived over the past 48 hours on strong west winds, creating firm wind slab in areas of our terrain. This clean new snow will be easy to identify over the dirty, refrozen old surface. The largest pockets will be found just under the rollover of Tuckerman with scattered, smaller pockets in the lee areas of NW winds. With an inch of snow possible today, the wind slab may grow in size, but will not affect the stability of the snowpack. Many areas, including most of Huntington Ravine, are scoured down to old surface. What remains is a very icy textured surface. Any slip or fall today will accelerate quickly so be aware of this when moving around the mountain.

WEATHER: It is cold. The current ambient air temperature on the Summit is -23F and -5F at Hermit Lake. Combine this with a west wind of 57 mph to get a wind chill of -65F! Keep warm today as it will remain this cold until tomorrow morning. Another inch of snow arrived yesterday on top of the 2.3” on Thursday. This morning may bring an additional inch of snow. Clouds should linger for the day with increasing winds into the 80 mph range and shifting to the NW.

SPRING HAZARDS: While it may not feel like spring today, the thaw from last week left some of our snowpack with a springtime look to it. Be on the lookout for the following:

  • Glide cracks, moats and crevasses have opened in places and may now be concealed with new snow, making identifying these extra difficult.
  • Undermined snow over stream channels can be a problem in gullies but more of a danger lower in the tributaries. Lots of holes in snow covering the streams have opened and may be hard to see from above. Falling into one, especially with skis or board strapped on, could be disastrous. Exiting Tuckerman Ravine on skis is becoming more of a challenge than some of the skiing above.
  • The cold snap today will encourage flash freezing of water available in the system. Today’s weather is prime for ice dams releasing a fire hydrant onto unsuspecting climbers in Huntington. This can happen naturally, but is more likely to occur from an ice tool swung into a bulge, creating the crack that will allow pent-up pressure to explode.
  • Long, sliding falls are possible today. Self-arresting on the old surface will be difficult to say the least. Competency with crampons will make travel safe 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 Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
  • Posted  8:15 a.m., Saturday, March 4, 2017. A new advisory will be issued tomorrow.

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

2017-03-04