Lawinenlagebericht

Presidential Range

Mount Washington Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

The threat of wet snow avalanches will increase as the day warms, and the possibility exists for a large wet avalanche to occur in isolated areas. These avalanches are most likely on steep slopes that face the sun at mid and upper elevations. The safest and best skiing will be found on aspects that receive indirect or partial sun where surface wetting is limited to the top inch or two. Track the movement of the sun and be aware that despite the warm temperatures, soft snow will firm up fast after it passes into the shade.  Avalanche danger today is MODERATE.

 Icefall is beginning to be a problem and glide cracks are opening up due to warm conditions. Adjust your travel plans accordingly.

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2

    Weak or no overnight freezes, warm temperatures, and buried weak layers are the recipe for generating wet slab avalanches. This avalanche problem is notoriously unpredictable and highly destructive. As melt-water works its way through the snowpack it weakens the snow, particularly in areas with crusts or pre-existing weak layers. We can say with certainty that today we have the first two ingredients. As for buried weak layers, our current snowpack is a mix of thick strong layers and includes some weaker layers. This avalanche type is unpredictable because of uncertainty in how vulnerable these weak layers are to the melt water from the snow surface.

    It’s worth noting that stability tests are unreliable tools for predicting wet slab avalanches due to the unpredictable nature of water movement (where and when) within the snowpack. Perhaps the best advice is to avoid or limit time in terrain where the obvious red flags indicate this as a problem. Today, safer and better skiing will be found on slopes that receive indirect or partial sun.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1

    Last night was the second night of barely below freezing temperatures at the highest elevations.  Snow is melting during the day, but warm overnight temperatures are preventing the snowpack from refreezing, creating a layer of wet slushy snow. The sloppy surface snow will move underfoot and possibly carry you. Be careful in steep terrain where falls have consequences. 

Avalanche Discussion

Today’s hazard rating was an interesting discussion for MWAC forecasters, mostly due to the unpredictable nature of wet slab avalanches. We begin with sensitivity and distribution to determine the likelihood of an avalanche problem. With the combination of likelihood and destructive size we arrive at a hazard rating. Yesterday’s hazard rating was Moderate at mid & upper elevations and projected today could be at Considerable. Our field time yesterday (reinforced by this observation for other locations ) showed that the warm sun is having the greatest impact on aspects directly facing the sun. Aspects receiving indirect sun are softening/wetting much less, and in the shade we found dry snow. This information limits the distribution of today’s avalanche problems and ultimately tips the scale to Moderate rather than Considerable for the most accurate hazard rating. Keep in mind that a Moderate hazard rating does include the possibility for large (up to D3) avalanches. 

Southeast Snowfields Avalanche – Summit Cone. March 29, 2014This is an example of a rare yet dangerous avalanche on Mt Washington which occured on a warming snowpack. Summit temperatures reached 34F with bright sun.

______________________________________________________________________________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. 

Our next free online event is coming up Thursday, March 25 @ 7PM -Opportunity and Cost - with Jake Risch. 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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