Bulletin d’avalanche

Presidential Range

Mount Washington Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Projected rains and warm temperatures today have elevated the risk of loose wet and wet slab avalanches across the mountains. You are most likely to find these avalanche problems in the middle elevation where a warm up overnight has allowed melting. Yesterday’s dry snow will become an avalanche problem as temperatures rise and rain falls.

Problèmes avalancheux

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5

    At 5AM this morning the temperatures in Tuckerman Ravine were almost 45F degrees. If rain saturates consolidated dry slabs it can compromise the shear strength of surface layers and result in failure. A wet slab avalanche can be very destructive due to the weight and volume of water and snows ability to absorb it. A wet slab avalanche is more likely to release at the new snow/old snow interface in our snowpack, which can be up to 4 feet deep in some locations.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–1.5

    Temperatures throughout the day will steadily increase and the summit of Mount Washington will be near 35F degrees during the afternoon. At 5AM this morning the temperatures in Tuckerman Ravine were almost 45F degrees. Rain on snow will decrease stability allowing for surface loose wet avalanches in some locations.

Avalanche Discussion

Two separate low pressure systems will affect the Presidential Mountains today bringing warm temperatures, extreme winds, and rain. Rain on snow will decrease the stability of the surface snowpack allowing for wet slab and loose wet avalanche activity today. Because of the uncertainty of timing and quantity of forecasted rain, we are most concerned about the larger and more destructive potential of the wet slab avalanche problem. 

In many cases loose wet avalanches are slow moving and easier to avoid than a dry slab, but the weight of saturated snow is overpowering and potentially destructive. Loose wet snow will be easy to recognize upon your ascent as you will find boot and ski penetration to be deep in previously dry snow.  

The NWS weather forecast calls for punishing westerly winds in excess of 120mph on the summit. These are some of the highest projected winds we have seen all season. Sideways precipitation can be expected in multiple forms throughout the day as temperatures push into the upper 40s then drop back to near freezing around dusk.

Please consider moving well out of the way of our snowcat if you encounter it on the Tuckerman Ravine Trail. This machine is large and the trail is narrow with many obstacles. If the snowcat operator stops or motions you to move off the trail more, please follow their instructions. 

Thanks to everyone for taking the 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.

Régions couvertes