Avalanche forecast

Presidential Range

Mount Washington Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Out of date — this forecast expired last year. You’re viewing past conditions, not the current bulletin.

Highlights

Warming temperatures and rain will create dangerous avalanche conditions above 3000 feet with naturally occurring wet snow avalanches possible. Lookout for heavy rain and wetting snow to know that the avalanche hazard is increasing.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    What and where is it:

    Yesterday’s newly formed wind slabs may be up to 2 feet thick and on north, east, and south aspects. With warming temperatures and rain today, these will be the most likely snow surfaces to slide as wet slabs.

    Old, stubborn wind slabs with poor, strong-over-weak structure have also been found on north, east, and south aspects. While less likely, it is possible that a period of heavy rain could weaken these layers and they could slide on the firm pencil hard surface below.

    On western aspects, snow surfaces have been found to be firm, which may limit water entering the snowpack, however, there is still slab structure in these aspects, and with rain falling at all elevations should be a consideration.

    How can you recognize it: 

    Any snow on a steep slope should be treated as an area that could slide today. The new slabs can be identified as areas of smooth, rounded snow that may be up to 2 feet thick. Old wind slabs are textured and may be hard to identify visually from textured snow surfaces around it.  While traveling through the snow, watch for wetting snow deeper than your boot tops, as this is a sign that you may have encountered a wet slab. How can you manage it:

    Actively look for areas of newly drifted snow and avoid deep drifts to limit your exposure to avalanche hazards. Periods of heavy rainfall and warming are red flags to look out for. The snowpack may give limited warning signs and wet slabs while slow, have dense, heavy, and destructive debris. There is no good way to assess structure, stability, and how much water is entering the snowpack without digging into the snow, and you will incur exposure to do this.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    What and where is it:

    Soft, unstructured snow will continue to warm and wet, while this is possible at all elevations, you will be most likely to find this at low elevation as the snow there has limited structure. 

    How can you recognize it: 

    Warm temperatures and rain on soft unstructured snow may cause roller balls as an early warning sign. Gloppy unstructured snow underfoot is also another indicator.

    How can you manage it:

    Consider limiting your time under steep terrain features with snow that could slide to limit your exposure to potential wet loose. While the size is not consequential, it could cause a fall on steep terrain with exposure below and should not be forgotten as a hazard today.

Avalanche Discussion

Wet snow avalanches are unpredictable and challenging to time as how much warming and ain will drive instability is difficult to answer. Things to consider are that this is the first significant warming this snowpack has seen, which is always a red flag. New slabs on east aspects will be the most reactive, but don’t discount snow surfaces elsewhere. 

To simply manage today, treat all steep snow slopes and areas that could slide. Commonly used instability tests may not be reliable and early research shows that Propagation Saw Tests may be your best instability test to assess wet snow. But while useful, these tests don’t show you the big picture. 

Overnight is when the bulk of the precipitation is forecast to fall and may be when things are most dangerous. On the other hand, after hours of warming and rain, if the snowpack is well saturated, rain may continue to just work its way through the snowpack producing limited avalanche activity. With a lot of unknowns, I plan to keep my terrain choices simple today.

Looking ahead, after this period of warming temperatures are forecast to plummet which will create a widespread refrozen surface and slide-for-life conditions on Friday and Saturday. These conditions can be some of the most dangerous in the Presidential Range, responsible for too many injuries and fatalities. Be sure to track the Mount Washington Observatory Higher Summits Forecast for weather over the coming days as this weekend may not have ideal conditions for skiing, snowboarding or hiking.

OBSERVATIONS: Please consider submitting an observation on our website or in the new Avy phone app of what you are seeing in your travels. Submitting an observation hones your skills, informs other users, and improves our forecasts.

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