Boletín de aludes

Logan

Utah Avalanche Center
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Peligro de aludes

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

There is CONSIDERABLE avalanche danger in the backcountry at all elevations. Natural avalanches are possible and people are likely to trigger avalanches on slopes steeper than 30°. Dangerous conditions exist on drifted slopes, and heavy snowfall and drifting from strong winds from the southwest will continue to elevate avalanche danger. The danger could rise to HIGH in windy terrain at upper elevations later today. If so, long running natural avalanches will become likely.

  • Make conservative decisions and evaluate snow and terrain carefully.
  • Avoid travel in drifted upper elevation terrain later today, and stay clear of avalanche runouts.

Problemas de aludes

  • Wind Slabs

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    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    This morning winds are blowing from the southwest, and they've been way more than strong enough to drift the foot or so of heavy powder from overnight. Avalanches of wind drifted storm snow, 1 to 3 feet thick, are possible on drifted slopes at all elevations, but will be larger and more likely for people to trigger on upper elevation slopes facing northwest through southeast.

    • Avoid corniced slopes and stiffer drifts on steep slopes near ridges and in and around terrain features like cliff bands, sub-ridges, mid-slope break-overs, and gully walls.
    • Wind slabs consist of stiffer drifted snow. Today, soft avalanches of drifted storm snow are likely.
    • Some wind slab avalanches could fail on a sugary persistent weak layer, and some might be triggered remotely.
    • Stay well clear of the freshly swollen cornices, which are likely to break further back than you might expect and could trigger wind slab avalanches below.
    • Natural avalanches are possible, especially during periods of intense drifting.

  • Persistent Slabs

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    • Límite del bosque
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    Probabilidad
    Likely
    Tamaño
    2

    There were many lower elevation areas with very weak faceted snow before the storm capped it with new snow. Prior to this week's storm the snow was particularly weak and faceted in protected lower elevation terrain, and poor snow structure and unstable snow can be found now on many lower elevation slopes.

    • Avalanches failing on a persistent weak layer are possible at all elevations but are notably also possible down lower, below about 7000' elevation.
    • Avalanches could be triggered remotely or from a distance.

    Watch Drew's video about similar lower elevation conditions in the foothills above Salt Lake City:

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    Around a foot of heavy snow fell overnight and another foot of accumulation is possible in the Bear River Range today. As heavy snow stacks up on steep slopes it will probably be pretty unstable in some areas. People are likely to trigger soft slab and loose avalanches of storm snow on slopes steeper than 30°. Natural avalanches will become increasingly likely. Natural avalanches are most likely during periods of particularly heavy snowfall.

Recent Activity

It was active in the Logan Zone over the weekend.

  • Saturday morning, I observed several large and long running natural cornice fall avalanches in the Wellsvilles, and others were reported from Logan Dry and off Cornice Ridge in the Bear River Range.
  • A group of sledders reports remotely triggering three wind slab avalanches in the Castle Rock area, just south of Naomi Peak.
  • Skiers remotely and then intentionally triggered a few small wind slab and cornice fall avalanches above the old Forestry Camp on the east side of Logan Canyon. HERE

Natural avalanches were common at lower elevations with this week's big storm, and they occurred in and around neighborhoods, breaking in backyards and sliding down into areas frequented by folks who usually don't have to worry much about avalanches. Friday, we observed recent natural avalanches in lower Green Canyon and up in Garden City.

There was an extensive natural avalanche cycle across the Logan Zone between Tuesday PM and Thursday AM, including dozens of slab avalanches at lower elevations <7000'. report and pictures HERE A very broad and long running natural avalanche(s) from last week's cycle was observed in the Wood Camp by a couple different parties on Saturday. HERE. and HERE

For a list of avalanches in the Logan Zone go HERE

Find a list of all recent observations & avalanches from across Utah HERE.

Snow and Weather

The National Weather Service has issued a Winter Storm Warning for the Logan Zone through Wednesday. The storm is exceeding expectations, and heavy snowfall and drifting by strengthening southwest winds will continue to elevate the avalanche danger, especially on drifted slopes. Avalanches are possible and will become more likely today in lower elevation areas where slabs of wind drifted snow are forming on slopes with poor snow structure. I plan to avoid avalanche terrain and continue to stay off and out from under drifted slopes at all elevations steeper than 30°.

The 8400' Tony Grove Snotel reports 12 inches of heavy new snow, with 1.6" SWE, mostly from overnight. It's 21° F this morning, and there is 118 inches of total snow. The wind is blowing from the southwest 25 to 30 mph and gusting well into the 50s at the 9700' CSI Logan Peak weather station. Here is the NWS point forecast for high elevations in the Central Bear River Range:

Today: Snow. The snow could be heavy at times. High near 24. Wind chill values as low as -1. Breezy, with a southwest wind 21 to 29 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 8 to 12 inches possible.

Tonight: Snow. The snow could be heavy at times. Widespread blowing snow. Low around 12. Wind chill values as low as -6. Windy, with a southwest wind 24 to 29 mph increasing to 31 to 36 mph in the evening. Chance of precipitation is 100%. New snow accumulation of 10 to 16 inches possible.

Tuesday: Snow. The snow could be heavy at times. High near 18. Wind chill values as low as -10. Windy, with a west southwest wind 24 to 32 mph. Chance of precipitation is 90%. New snow accumulation of 4 to 8 inches possible.

The productive storm will continue to produce significant accumulations heading into the week, with a break late Wednesday and Thursday.

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 Logan and Ogden Ranger Districts HERE, and a close up of 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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