Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Wed
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger remains elevated today, with human-triggering of wind slabs likely in steep terrain where wind has drifted snow overnight. These wind slab avalanches will be large enough to bury a person. Natural avalanches are possible on easterly aspects in the steepest terrain, particularly across the Headwall of Tuckerman Ravine, due to extreme northwest wind drifting snow last night and this morning. Avalanche danger is Considerable today. Cautious route-finding is essential due to dangerous avalanche conditions.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–3

    Early this morning, west-northwest wind has reached the highest velocity since the 17th. The nickel and diming that has occurred since then has left plenty of snow in the alpine fetch zones to build large and dangerous wind slabs. The icy bed surface that formed last Tuesday has proven to be a poor bonding surface for new snow in some areas with good bonding in others. This spatial variability should have you carefully considering your exposure level and group travel practices in the terrain today, even as wind diminishes. These slabs are likely to be on the firmer side (1F/1F+) in many places due to higher wind speeds, but recent and continued wind loading or a human trigger may tip the scales past what the weak layers below can handle.  A very large (D3) avalanche in Tuckerman Ravine (Chute, Center Bowl, Sluice?) isn’t out of the question. Look for large, smooth pillows of snow in mid-slope start zones. Recent southwesterly winds and the typical swirling winds have crossloaded multiple aspects.

Avalanche Discussion

An active weather pattern has set us up for a resurfacing of the upper snowpack over the ice crust formed on the 16th. Wind speed and direction has been variable but fairly moderate by our standards. It is very likely that quite a bit of snow remains in the alpine to serve as building blocks for new wind slabs. Uncertainty does exist in the forecast rating with a chance that recent wind slabs are on the stubborn side in most areas. But the increase in wind speed and continued observations of blowing snow with a good bit of snow available for transport are a red flag that can’t be ignored. Assume that natural avalanches can come from slopes above. Lots of hasty hand pits will help you gauge the distribution and sensitivity of recently wind affected/deposited snow.  Various crusts that exist in the snowpack  through all elevations are in various states of decay. These are worth tracking and considering in your decision making as they often create faceting layers.

 

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, February 25 @ 7PM - Barriers to Cognition and Perception with Blake Keogh  - 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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