Bulletin d’avalanche

Logan

Utah Avalanche Center
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Danger d’avalanche

  • Alpin
  • Limite forestière
  • Sous la limite forestière
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Points saillants

Areas with HIGH avalanche danger exist on drifted upper and mid elevation slopes, especially in the Northern Bear River Range. There is CONSIDERABLE danger on all other drifted slopes across the zone, including on many lower elevation slopes with poor snow structure. People are likely to trigger dangerous avalanches today, and large and long running natural avalanches are possible.

People should stay off of and out from under drifted slopes steeper than 30°

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    2

    We've found buried layers of sugary snow at all elevations and on slopes facing every direction. In areas where the snow is shallow, less than about 3 feet deep, the basal layers of the snowpack are very loose and sugary. If you get off your sled or skis you sink all the way to the ground and it's pretty easy to get the sled stuck if you sink and spin your track into the bottomless sugary snow. Avalanches failing on a buried persistent weak layer are most likely on slopes with significant recent accumulations of wind drifted snow.

    • Sugary or faceted November snow makes up the most widespread PWL in the zone, but there is another now, consisting of feathery surface hoar or small grained near surface facets that was on the snow surface before yesterday's storm.
    • Red Flags indicating a persistent weak layer instability will include audible collapses or whumpfs and shooting cracks, but sometimes no red flags are apparent, and you have to dig down into the snow to find the sugary weak layer.

    • Slab avalanches failing on a buried persistent weak layer could be remotely triggered from a distance, and hopefully not from below.

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    3

    Human triggered avalanches of wind drifted snow are likely in drifted terrain at all elevations. Long running and large natural avalanches are possible. Avalanches of wind drifted snow failing on a buried persistent weak layer could be 1 to 4 feet deep and a few hundred feet wide.

    • Slabs of drifted snow formed on the lee side of major ridges, under cornices, and in and around terrain features like sub-ridges, saddles, cliff bands, and gully walls.
    • People should stay off of and out from under all recently drifted slopes in the backcountry steeper than about 30°.

    Shooting cracks in wind drifted snow like this are a sure sign of instability.

Additional Info

Take the all-new online avalanche courses the UAC built for Know Before You Go or take other online courses listed on the KBYG website (Develop skills -> Online Learning).

Remember, when you leave the ski area boundary, Beaver Mt or Cherry Peak, you are entering the backcountry, and you could trigger dangerous avalanches....

  • Put fresh batteries in your transceiver and inspect your shovel and probe.
  • Practice Companion Rescue with your backcountry partners.

Special Announcement

As the end of the year approaches, please consider a donation to the UAC to support avalanche forecasting.

Recent Activity

Natural avalanches were fairly widespread during yesterday's stormy weather. We observed several small naturals in Logan and Beaver Canyons during the day. A party reports remotely triggering an avalanche of wind drifted snow in Cherry Creek Canyon, and there was some activity in the backcountry on the backside of Beaver Mountain.

***See our updated list of observed avalanches from the Logan Zone HERE and from across Utah HERE

Snow and Weather

Very dangerous conditions exist because yesterday's extremely strong winds drifted tons of snow and created thick slabs overloading slopes with buried persistent weak layers. The danger could be worse in the northern part of the zone where more new snow fell and drifting was quite intense.

The snow from November has become a widespread and tricky persistent weak layer plaguing many slopes at all elevations in the Logan Zone.

This morning: Winds diminished significantly overnight and it's fairly calm at the Logan Summit weather station, where crazy up-canyon winds were gusting in the 70 mph range for much of the day yesterday. I'm reading 1° F and there is 6 inches of wind blasted new snow from the last 24 hours at the 8400' Tony Grove Snotel, which reports 52 inches of total snow.

Today will be mostly sunny and cold, with 8500' high temperatures near 9° F. West-northwest winds will blow 11 to 14 mph and wind chill values will be as low as -25° F.

Tonight, cloudiness and temperatures will increase and some snow is possible. Temperatures will climb to around 13° F by morning, and west-southwest winds will blow around 10 mph. Around a half inch of new snow is possible.

Tomorrow will be cloudy and snow is likely. 8500' high temperatures will be around 21° F, with 11 mph winds from the west-southwest, and 1 to 3 inches of accumulation.

The weather for the Christmas weekend looks unsettled and somewhat cloudy, and the next chance for significant storminess and accumulating snow will effect the Logan Zone on Tuesday

General Announcements

Please submit your observations from the backcountry HERE.

For a list of avalanche classes from the Utah Avalanche Center go HERE

For information on where you can ride your sled or snowbike, check out this map of the winter travel plan for the Tony Grove and Franklin Basin Areas HERE.

This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.

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