Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

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

This morning, generally safe avalanche conditions exist across the range. Later in the day, a mix of snow, sleet, and rain will increase the chance of wet avalanches. Wet avalanches caused by heavy rain are often unpredictable and can happen spontaneously without any other warning signs. It is worth respecting this uncertainty and giving water a chance to drain from the snowpack before spending long periods of time in avalanche terrain.

Problemi valanghivi

  • Loose Wet

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

    A mixture of snow, sleet, and rain accumulating on top of old, hard snow surfaces increases the chance of triggering a small loose wet avalanche late in the day. If frozen precipitation is able to accumulate, expect a higher chance of loose-wet avalanches. If precipitation falls mostly as sleet and rain, this avalanche problem may not form at all. This avalanche type is generally slow-moving, but it’s heavy weight can be deceivingly powerful. Look out for sloughing and poor bonding of new precipitation on the old snow surface.

  • Wet Slabs

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

    The amount of water moving underneath and within the snowpack is the main driver of this avalanche problem today. Likelihood of wet slab avalanches will increase in the late afternoon, evening, and early morning hours as rainfall totals increase. This hard to predict avalanche problem should be considered in the decision making process if traveling late this afternoon or tonight. 

Avalanche Discussion

Even though temperatures remained mild overnight, expect the existing snow in avalanche terrain at the middle and upper elevations to be cold and frozen with a hard snow surface and crust in most places. Triggering an avalanche at these elevations is unlikely prior to the start of incoming mixed precipitation, which is forecast to begin later this afternoon. 

There is uncertainty today surrounding the type of accumulation that will fall at different elevations and in different parts of the range. If cold temperatures persist longer into the day and frozen precipitation is able to accumulate, expect a higher chance of loose-wet avalanches. If precipitation falls mostly as sleet and rain, this avalanche problem may not form at all.

There is additional uncertainty around how another 0.75 inches of rain will affect the bottom and inner layers of the snowpack. Though wet slab avalanches are unlikely, they are not out of the question. This recent activity in Hillman’s Highway highlights the power and uncertainty that rain can have when introduced to the snowpack. How close are other areas to a similar outcome? We may never know. 

Thanks to everyone who has taken time to submit observations of snow and avalanche conditions, both inside and outside our avalanche forecast area. Please keep them coming.

The Lion Head Summer Trail is closed for the season due to avalanche risk. The Lion Head Winter Route is open.

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