Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

A mix of precipitation types combined with shifting wind today will make traveling in avalanche terrain dangerous. Triggering an existing wind slab formed before this storm remains a possibility.  Newly developing wind slabs this morning, while small, could add enough stress to existing large, hard slabs and increase the chance of triggering by a human. The possible addition of rain into the mix can also trigger an existing large slab. When the temperature drops and the wind shifts west in the afternoon, watch for wind slabs developing on steep slopes at mid and upper elevations. Evaluate snow and falling precip types carefully. Though freezing rain is forecasted, if enough liquid rain falls and penetrates the snowpack, natural avalanches may occur. Avalanche danger today is MODERATE.

Avalanche problems

  • Wind Slabs

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

    The existing avalanche problem of wind slabs formed several days ago remains a concern, and capable of producing a large avalanche. The current snow storm is bringing a mix of precipitation types to add stress to the existing slabs. It will also create new wind slabs, especially in the afternoon when temperatures drop and the wind shifts to the west. Fresh wind slabs this morning will be on the smaller side, found on north aspects and cross loaded on other aspects. 

    Watch for wind shifting to the west as the precipitation turns back to snow. Increasing west wind will use any additional snow to build wind slabs, likely on an icy crust primarily in east facing ravines.  New wind slab development today will depend on elevation, temperature and snow totals. While lower elevations may see less snow, limiting the size of new windslabs, they will be forming on a weak snowpack. This will lead to an increased probability of producing an avalanche. 

  • Wet Slabs

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

    The mixed precipitation types today include a chance for rain. With forecasted temperatures just under freezing, it’s likely that rain will freeze on the snow surface creating a crust. The possibility exists that if temperatures rise just a little, liquid rain will fall and penetrate into the snowpack, providing the conditions for buried weak layers to fail. While this scenario is unlikely, it’s significant enough to include as an avalanche problem due to the unpredictability and the fact that avalanches may happen naturally. Watch for rain and temperatures above freezing as red flags for this avalanche problem type.  

     

Avalanche Discussion

Today’s avalanche forecast comes with a reasonably high degree of uncertainty due to snow totals and precipitation types hinging on temperature, which itself includes a degree of uncertainty. Temperatures will be below at or above the freezing point for most of the forecast area. Small temperature changes today are hard to predict, yet will have an impact on how all this plays out. Be conservative in your terrain choices today.

A complete incident analysis and report of the fatal avalanche accident that occured in the Ammonoosuc Ravine on February 1 is available here. There are learning opportunities in the stories of accident reports from our database as well as from across the country. Taking the time to read and honestly reflect on your own behavior in the backcountry is worthwhile.

Information on all US avalanche fatalities can be found here with details and accident reports appearing as they are submitted to the CAIC. Two more fatalities occurred over the weekend in Colorado including one involving a very large, skier-triggered wind slab. The skier was wearing a deployed airbag, was buried shallowly and skiing alone.

An interview with Simon Trautman of the National Avalanche Center on the recent cluster of fatal avalanche accidents can be found here. 

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, February 18 @ 7PM - Avalanche Awareness talk with Pat Scanlan: Stealing from the Ski Guides Toolbox - 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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