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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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The danger will rise to CONSIDERABLE again in the midday heat, and dangerous wet avalanche conditions will develop on sunny slopes. Large natural avalanches are possible, and in sunny terrain and in rocky areas with shallow snow, people could trigger dangerous slab avalanches up to three feet deep and a couple hundred feet wide, failing on a buried persistent weak layer.

Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential for safe travel in the backcountry today.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3

    Unseasonably warm temperatures and sun will cause the snowpack to become again saturated and unstable in the day's heat.

    • If the snow surface feels sloppy and you sink in more than a few inches, move to a shadier aspect or lower-angle terrain.
    • Roller balls and pinwheels are signs that the snow is becoming unstable.
    • Avoid being below big sunny slopes and in avalanche run-out zones as the day warms.
    • A wet loose avalanche overrunning a slope with poor snow structure could initiate a much larger and more dangerous wet slab or hard slab avalanche.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3

    Today, human-triggered slab avalanches failing on a buried persistent weak layer could be large and life-threatening. During the last big storm, heavy snowfall and strong winds overloaded slopes plagued by a widespread persistent weak layer that formed throughout the December dry spell. The shock of rapidly rising temperatures on Sunday caused some large natural hard slab avalanches in the zone. Daytime heat softened the stiff slab layer and moistened (lubed) the problem persistent weak layer, making the snow unstable.

    • Avalanches might be triggered remotely, from a distance, or even from below!
    • Audible collapsing (or whumpfs), cracking, and recent avalanches are obvious signs of instability. However, these red flags may not be present when avalanches failing on a persistent weak layer occur.

Special Announcement

Sign up for forecast region-specific text message alerts. You will receive messages about changing avalanche conditions, watches, and warnings...HERE.

Recent Activity

A natural wet and hard slab avalanche cycle occurred Sunday due to rapid warming. The wet activity mainly occurred on south-facing slopes at all elevations, and some large slab avalanches failed on the December persistent weak layer.

  • Evidence of large natural wet slab avalanche that occurred during the heat of the day was observed yesterday on Mitton Peak in the Wellsville Mountain Wilderness. The 2' deep and 100' wide avalanche, visible from Highway 89/91, started at around 8400' in elevation on a southeast-facing slope and ran close to 2000 vrt'
  • A very large natural wet avalanche was witnessed by a professional observer in Green Canyon a little after noon on Sunday. see the report
  • A large avalanche on Wilderness Peak near Gibson Lakes in Franklin Basin was either naturally occurring or it was remotely triggered by riders on Sunday. It was reported on Monday by riders who noticed recent sled tracks in the area. report is here

A large hard slab avalanche on Wilderness Peak was either a natural due to heat shock or it was remotely triggered by riders on Sunday.

Check out local observations and avalanches HERE.

Snow and Weather

A poor overnight refreeze, daytime heating and abundant sunshine will cause the snow to become saturated and unstable on sunny slopes at mid and upper elevations. Even though temperatures stayed above freezing last night up high, the clear skies allowed for a decent surface refreeze, and the snow is now crusty at all elevations. The "Springtime in January" heat has significantly damaged last week's nice powder, and snow conditions have become sub-par. The good news is we have excellent coverage, great weather, visibility, and very supportive snow, creating excellent "touring" and avalanche viewing conditions.

Wind blowing from the south increased significantly overnight, and this morning , the 9700' CSI Logan Peak weather station is recording average wind speeds of around 30 mph, and it's 33° F. At 9500' on Paris Peak, it’s 30° F, and winds are blowing 10 to 20 mph from the SSW. The Tony Grove Snotel at 8400' reports 34° F and 72 inches of total snow containing around 120% of average SWE (Snow Water Equivalent).

Today, expect high temperatures at 8500' over 40° F again, with sunny skies and winds blowing from the south-southwest. Tomorrow, we can expect increasing clouds, cooling temperatures, 15 to 20 mph wind from the south-southeast, and light snowfall in the afternoon. The National Weather Service has issued a Winter Weather Advisory beginning tomorrow afternoon and continuing through Saturday. Snow is expected tomorrow night, with 2 to 4 inches of accumulation possible, winds blowing out of the east, and temperatures dropping to around 24° F. Snowfall will increase on Friday, with 4 to 8 inches in the forecast for upper-elevation slopes, winds veering from the west, and 8500' high temperatures around 32° F. Expect snow to continue Friday night and Saturday with a few additional inches of accumulation likely.

General Announcements

-Read my recent blog about wind, drifting, and avalanches HERE

-Come practice companion rescue with your backcountry partners at the Franklin Basin TH beacon training park. video HERE.

-For all questions on forecasts, education, Know Before You Go, events, online purchases, or fundraising, call 801-365-5522.

-To report an avalanche or submit an observation from the backcountry, go HERE.

-We will update this forecast by 7:30 AM tomorrow. 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.

Régions couvertes