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Avalanche Forecast

Archived

Mar 20th, 2024–Mar 21st, 2024

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Ghost.

Snow and wind will elevate the avalanche hazard tomorrow. How well the new snow sticks to the crust will be a key variable in determining how far the hazard will increase. Approach avalanche terrain with caution.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported today.

Snowpack Summary

Expect to find the new snow(5-10cm) lying on top of an extensive frozen crust at all elevations, especially on solar aspects. This crust is providing strong bridging over any weak layers. On the shady aspects, there are older lingering surface wind slabs under this new snow that one should pay attention to. Both the persistent slab and the deep persistent slab could still be triggered on steep open alpine features. Take the time to dig and investigate these buried layers. You might see some sluffing in steep terrain with this new snow.

Weather Summary

Snow has already begun to fall with amounts expected to build overnight and into tomorrow. By morning, expect 10cm, then another 10cm throughout the day. Winds will be very different based on elevation. Valley bottom winds will be light and from the NE, while upper level winds will be out of the East. Speeds will all be light. Temperatures will range from -8 to -4.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Conditions may have improved, but be mindful that deep instabilities are still present.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.