Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

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

In sintesi

You could trigger an avalanche in areas of softer, wind drifted snow created from new snow and increasing winds today. These drifts will be found in steep east-facing and south-facing slopes at middle and upper elevations. Lookout for blowing snow at ridgelines, shooting cracks, and snow deeper than your boot tops as signs of increasing avalanche hazard.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    There are still small reactive wind slabs in sheltered terrain features at middle and upper elevations. Look for softer, smoother snow and evaluate that carefully. Visual observations of terrain and snow at various elevations will be important in travel today. Using hand shears to isolate the surface snow will give you an idea of the sensitivity of the wind slabs sitting on top of a slick melt-freeze crust, and new snow falling on top of them.

    Later this afternoon, new snow and wind has the potential to add to the size, distribution, and sensitivity of the wind slabs in terrain. This new snow and wind may obscure start zones and challenge visual observations and your identifying more sensitive snow. Red flags to lookout for today will be blowing snow at ridgelines, shooting cracks underfoot, and deeper denser snow that is over your boot tops. If you find yourself in snow like this, consider that you have found a wind slab that has the size that could bury you. 

    Evaluating the new snow and the wind will be the best predictor of increasing hazards today. 

Avalanche Discussion

The forecast has sustained multiple days at moderate, and this is largely because of consistently low wind speeds (by Mount Washington standards). Typically, wind slabs problems are rendered stubborn to unreactive in the Whites by hours of strong to extreme winds. Over the last three days winds have averaged 18 mph with peak gusts topping out at 42 mph. 

There was concern that the existing problem was lingering due to light winds, a slick surface interface, and cold temperatures. Light winds created more sensitive wind slabs, the slick surface is harder to bond to, and consistent cold temperatures also might have limited bonding. Observations yesterday (thank you ski community!) discuss stubborn and well bonded wind slabs that were small and found in sheltered terrain.

Today’s moderate hazard is factoring in the new snow and stronger wind that has the potential to create new wind slabs. Snow is forecast to begin in the afternoon and is likely when the hazard will begin to increase.

Watch out for increasing wind speeds to transport remaining snow from the 2.5 inches from January 28th. The low winds have transported some of the snow, but likely not all of the snow that is available. Today’s winds are forecast to be higher than they have in days, so take advantage of visibility in the morning to look out for wind loading at ridgelines. If you find blowing snow this is a sign that gullies are actively loading and that the avalanche hazard is increasing. 

If snow totals are less than forecast or wind speeds are on the low end, there is potential that we will not reach a moderate hazard rating today. 

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