Avalanche Advisory for Saturday, March 15, 2014

This advisory expires at 12:00 midnight. Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, and Chute have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. All other forecast areas have Moderate avalanche danger.  Natural avalanches are unlikely and human triggered avalanches are possible. Huntington Ravine has MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern. AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Widespread avalanche activity in the past 36-48 hours are one indication of potential instability. Field work yesterday revealed most slopes had reloaded with wind slabs or our second avalanche threat which is piles of sluff debris.  Areas where these firm slabs exist could be triggered by a load of skiers or climbers finding a thin spot in the slab and would likely result in an avalanche large enough to bury a person. WEATHER:  Overcast, flat light and potential snow showers today will challenge visual assessments. West winds around 55 mph will increase late in the day towards 80 and temperatures will fall from their balmy position at 20 F on the summit, 39 F at Pinkham Notch, into another unseasonable deep freeze.  SNOWPACK: Continued reloading occurred yesterday due to blowing snow with a shifting wind to the SW. Though temperatures warmed yesterday increasing the stabilizing process to some degree, it is unlikely this warming reached deep enough into the snowpack to create bonds where these deeper weak layers exist. Yesterday, Chris, Joe and I counted dozens of crown lines from Boott Spur through the Tuckerman cirque and over to the slopes beneath Lion Head. These crowns ranged in size from a foot to over 5 feet deep visible even after considerable reloading. Crowns in Huntington were also visible with significant debris beneath South with other piles scattered through the Fan and beneath Harvard ice bulge. Avalanches due to the failure of a number of weak layers from mid-storm snow, ice crust, and a layer of needle forms from a couple of weeks ago. Ice crust from the January 21 rain event was also a player and was ripped up by avalanches. Chunks of this crust was visible in debris as well as where it was blown across the floor and deposited on the surface. The trigger during the storm was the increased load of snow blown in. Today, climbers and skiers could be the load and trigger without careful routefinding.  Avalanche danger in Right Gully and Lobster Claw is often quick to fall due to a combination of aspect, terrain features and  compaction, but these areas still require solid skills to pass through safely. The Lower Snowfield area has filled in due to substantial avalanching and sluffing from above and looks an awful lot like it did prior to the skier triggered avalanche last April under similar conditions.  While Damnation and North in Huntington appeared to be near the lower end of Moderate, I would stay heads up on all the routes there due to the consequence of triggering what are potentially hard slabs of the larger variety. Not many slope testers have travelled through yet. Temperatures near and below 0F in our forecast areas tonight will continue destabilizing areas with buried temperature crust and associated facet growth. For more info check out a Youtube post from yesterday. 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 8:30a.m. 03-15-2014. 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 2014-03-15 Print friendly