Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Triggering a large slab avalanche is possible today as temperatures rise and snow weakens. Small sluffs are certain to occur and may contribute to the mass needed to trigger one of these larger slabs. The snowpack near bushes, in confined gullies and around rocks will heat up the fastest. Be particularly cautious on large, uniform slopes such as the East Snowfields on the summit of Mount Washington or in south-facing Oakes Gulf where more expansive slabs may fail. On most aspects, icy crusts will be just under the snow surface and will require crampons and an ice axe for safe travel. Avalanche danger is MODERATE today due to the potential for large, human triggered avalanches. Icefall, which is already a hazard at lower elevations, will become possible at ravine elevations today.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Wind slabs that formed on Thursday & Thursday night will warm rapidly today. Instability will increase as heat penetrates the snowpack and loosen bonds between snow grains. The upper snowpack will lose cohesion first, leading to loose, wet human triggered sluffs. Slabs that were not cut-up by ski traffic yesterday is of most concern for wet slabs to fail. As snow becomes mushy, seek out shadier aspects or areas of previously wind scoured or “skied off” snow surfaces. The ice crust that exists beneath the upper snowpack could be the bed surface lubricated by melting snow. The aprons of accumulated snow beneath steep terrain are of greatest concern due to the potentially large size avalanche which could result.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1

    If you find yourself traveling on steep slopes with wet snow on top, triggering one of these slides will be possible. Pay attention to the snow surface as you travel, dig down with your hands. If you are finding wet snow (easy to make a snowball) more than a few inches deep, it's a good idea to avoid steep slopes. A small wet loose avalanche initiated under your skis is capable of pulling you off balance, resulting in a fall or knocking someone below off their feet. The lowest elevations have generally passed through the warming trend already but be wary of exceptions where larger amounts of snow, which were previously shaded, become warm in the current weather.

Avalanche Discussion

Nailing down the timing of wet slab avalanche problem types is a challenge in any snow climate, but is particularly hard in our wind distributed snowpack where layer thickness and density varies so widely. The only real solution is to be observant while moving through the terrain and look for the signs that indicate the rising danger. Rapid warming is one of the 6 classic red flags that indicate a trend towards avalanche danger. It would be wise to heed them today. Not only will the skiing be better in slightly firmer snow, you will run less risk in triggering an avalanche.

 

The following video contains some images of the snow slab and snow surface characteristics leading into the warming that will occur this week. The shear quality of the slab in the hasty test performed with an ice axe illuminates the concerns about the interface between the existing wind slabs and the icy crust beneath. 

https://www.instagram.com/p/CMnsuZ-jYek/?utm_source=ig_web_copy_link

Hard wind slabs, ice crusts and perhaps some faceted layers exist in the snowpack and will become a concern for various reasons as warming continues this week. Keep an eye on temperature trends and remember that cold air pooling in valley locations may not be indicative of the trend in air temperatures at higher elevations. The current temperature in North Conway (400’ elev.) is 19F at the moment and 30F on the summit of Mount Washington. Freezing temperatures overnight help stabilize the snowpack.

_________________________________

Thanks to everyone who participated in the 20th Annual FOTR Inferno event yesterday! A fun time was had by all, despite the high winds, and significant money was raised to support this avalanche forecast and the mission of Mount Washington Avalanche Center.

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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