Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Strong wind from the northwest drifted snow into wind slabs on steep east facing slopes and gullies. The largest wind slabs will be limited to areas that are downwind of the most expansive areas of fetch such as Tuckerman Ravine and Gulf of Slides. It is possible for a skier or climber to trigger an avalanche in these isolated areas which may contain slabs large enough to bury a person. Rock hard snow and ice crust are widespread at lower elevations and in higher elevation wind scoured areas, making long sliding fall conditions a serious concern too. Avalanche danger today is MODERATE on wind loaded slopes. Natural avalanches are unlikely though human triggered avalanches are possible.

TONIGHT! Thursday, March 4 @ 7PM -Avalanche Awareness class with Al Mandell - A Free Zoom Webinar.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    As is often the case in our windy range, you will wind slabs distributed widely across the terrain. You'll even find them lower in the woods following high winds on Tuesday. Most of the wind slabs in avalanche terrain will be stubborn to human triggering due the firm nature of the upper slab and a weak layer beneath that is not particularly weak (likely just 1 hardness step). False unstable tests are common in these slabs which rightly identify a planar, weak layer of softer snow or ice crust interface but fail to account for the strength of the overlying slab. Hollow sounding areas of smooth snow and energetic shooting cracks are good indicators that you’ve found a wind slab. Firm slabs typically require a thin spot for a person to trigger them but the increased load to trigger them could also come from continued loading of more wind blown snow.

    Evaluate the consequences of triggering even a small slide and make your terrain choices accordingly. Long sliding falls may be possible where the wind has stripped any new snow, exposing a refrozen crust formed from a warm period Sunday morning. Carrying proper self-arrest tools will be your only ability to stop if you begin a sliding fall on even low angle slopes.

Avalanche Discussion

Cold temperatures and high winds will not be conducive to careful decision making or discussions in the alpine areas today. The shrinking safety margin also raises the consequences in the event of an injury or accident. Prepare carefully and choose increasingly conservative objectives when other factors, such as cold weather, shrink your margin. 

 

A good but non-standardized snow test to help identify the difference in snow hardness under your feet today is the Ski Pole Penetrometer test. In your travels, stick your ski pole down into the snowpack feeling for changes in density on the way down, and back up. In our current firm snow, handle first is probably best, but in softer snow basket first is more sensitive to subtle changes. If you find firm snow over soft snow today you’ve found the snow structure that can lead to an avalanche when other necessary ingredients, like a steep slope and a trigger, are added..

 

Observations in the field on Wednesday were challenging with downed trees, very high wind and cold temperatures. What the crew did see was enough to confirm the results of 18 hours of wind in the 70-100 mph range. Lee aspects are left with wind slabs structured with thick, hard snow over one-step softer snow and no signs of propagation. Distribution of the new wind slabs looked to be fairly widespread, with surprisingly large piles of drifted snow;   given the small snow totals this suggests the strong wind was able to find older snow for transport. Limited visibility prevented a clear view of start zones high in the gullies, but small windows presented wind scoured surfaces and the lustrous appearance of old refrozen crusts. 

 

Information on all US avalanche fatalities can be found here with details and accident reports appearing as they are submitted to the CAIC.  An interview with Simon Trautman of the National Avalanche Center on the recent cluster of fatal avalanche accidents can be found here. 

 

Thanks to everyone for taking the time to submit all the observations of snow and avalanche conditions, both inside and outside our avalanche forecast area. Please keep them coming. 

 

Your avalanche, snowpack, or weather observations are extremely valuable to the forecasters at MWAC. Help create a more accurate avalanche forecast by submitting your observations here. 

 

Listen to the weekly MWAC Outreach Podcast provided by Ski The Whites. Discussions include snowpack information, weekend outlook, and general avalanche related info. 

 

Thursday, March 4 @ 7PM -Avalanche Awareness class with Al Mandell - A Free Zoom Webinar.

 

The Harvard Cabin is open for camping only with no entry allowed inside the cabin. There is no access to the breezeway at HoJos.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This forecast 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.
  • Avalanche danger may change when actual weather differs from the higher summits forecast.

For more information contact the US Forest Service Snow Rangers, AMC visitor services staff at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or seasonally at the Harvard Cabin (generally December 1 through March 31). The Mount Washington Ski Patrol is also available on spring weekends.

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