Bollettino valanghe

Moab

Utah Avalanche Center
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Pericolo valanghe

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

There is a MODERATE danger for triggering an avalanche on a buried persistent weak layer on slopes that face W-N-SE. The danger is greatest on steep northerly aspects near treeline and above where accumulated and drifted snow has built slabs 2'-4' thick over this weak layer. While there is a lower likelihood of triggering an avalanche right now, the consequences of being caught in a slide remain dangerous. Strong winds and blowing and drifting snow have produced a MODERATE danger for triggering an avalanche in wind drifted snow on all aspects above treeline.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    A persistent weak layer of faceted snow that developed during the cold dry period in mid November exists on aspects that face W-N-SE. The greatest danger exists on slopes facing NW-N-E, where wind drifted snow has built thick slabs on top. These hard slabs are 1-4' thick and can produce very large, deep, and potentially deadly avalanches. Out of the wind zone an active weather pattern throughout December has stacked plenty of storm snow and built a cohesive and well connected slab on top of the weak, sugary, faceted snow. This weak layer has become less reactive in recent stability tests (for more details see my obs from Monday). Obvious signs of instability are becoming harder to find each day. What hasn't changed is the poor snowpack structure. Likely places to trigger an avalanche right now include:

    • Slope margins where the slab is more thin and the weight of a rider is more likely to trigger the weak layer
    • Shallow, rocky areas with a thin snowpack
    • Steep convex rollovers

    You can avoid this avalanche problem by keeping your slope angles below 30 degrees, ride slopes that are heavily anchored by dense trees, or ride South facing slopes that do not harbor this dangerous persistent weak layer.

    This video was shot Monday 12-19.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1

    On Tuesday afternoon winds out of the South picked up intensity and starting blowing and drifting snow. Overnight the winds have shifted and are blowing out of the WNW. Westerlies will be on the increase today with the strongest winds occurring tonight. Look for fresh wind drifts to be developing above tree line today. Fresh drifts will be shallow and sensitive. Newly formed wind slabs tend to be more reactive to skier triggering. Any triggered wind drift has the potential to step down and trigger a deeper and more dangerous avalanche, especially on previously loaded slopes that face NW-N-E.

Special Announcement

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

Road Conditions: The road is snowpacked and slick. AWD and good tires are required.

Grooming: Trails were groomed Saturday but they have seen a lot of traffic over the weekend.

Recent Activity

No new avalanches have been observed. The most recent avalanches ran on or around Dec 13. Here is a complete list of avalanches in the La Sals.

Snow and Weather

24 Hour Snow 0" 72 Hour Snow 0" Season Total Snow 79" Base Depth at Gold Basin 40"

Winds on Pre Laurel Peak NW 23 G 28 Temp 9F

Weather

It is currently 9 degrees under clear skies in Gold Basin this morning. An Arctic cold front will affect northern Utah and Colorado today. This will bring moderate to strong winds to the La Sals. Winds will be out of the West at 15-20 mph and gust to 30. Winds will increase throughout the day. Tonight there will be a chance of snow showers with little or no accumulation and winds will gust into the 40's. Tomorrow will be sunny, cold, and windy.

General Conditions

The powder party might be over as conditions took a bit of a hit yesterday. Tuesday's thin cloud cover had a slight green housing effect and Monday's cold dry powder turned dense and creamy. Increasing winds throughout the day will also do a number on the snow surface. You can still find nice, settled powder in sheltered locations. The avalanche danger is slowly dialing down, but a well defined persistent weak layer of faceted snow exists and the consequences of getting caught in a slide remain the same. Deep, dangerous, and potentially un-survivable human triggered avalanches remain possible, particularly on steep, northerly aspects near treeline and above. For more on this, check out Eric's excellent blog post about Moderate Danger With a Persistent Weak Layer.

If you're getting out in the backcountry please let us know what you are seeing by submitting an observation . Here are the most recent observations.

Snowpack and Weather Data

Gold Basin Storm Stake (10,000')

Gold Basin SNOTEL site (10,000')

SNOTEL site near Geyser Pass Winter Trailhead (9600')

Wind Station on Pre-Laurel Peak (11,400')

NWS forecast for the La Sal Mountains.

Additional Info

As we head into a dry period it's good to know that at least for now, we are at 128% of normal snowpack for this time of year. The blue line is where we are currently, the purple line is the average, and the green line is where we were last year at this time.

General Announcements

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. This forecast will be updated by 7:30 tomorrow morning.

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