Bollettino valanghe

Uintas

Utah Avalanche Center
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Pericolo valanghe

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco
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In sintesi

VERY DANGEROUS AVALANCHE CONDITIONS EXIST. The snowpack has been teetering near it's breaking point for some time, and yesterday's snowfall combined with strong westerly winds has pushed it over the edge.

It's very simple today, the danger is HIGH above treeline, and CONSIDERABLE near treeline. In both areas, human triggered avalanches are likely, especially on slopes loaded by recent winds.

Below treeline, human triggered avalanches are possible and the avalanche danger is MODERATE.

There is still plenty of riding you can do and be safe from avalanches- Simply stick with slopes less than 30 degrees in steepness where avalanches generally don't happen and make sure there's no steep terrain above or adjacent to where you're riding. The Uinta's have lots of this fun rolling terrain.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    3

    Most slopes have persistent weak layers of faceted snow in the bottom half of the snowpack. New snow that fell in January has formed a slab on top of these weak layers. Imagine a building with a weak foundation but we keep adding additional floors on top - eventually the whole structure will collapse. New snow and wind drifted snow has added more floors to this unstable structure.

    While most slopes have these weak layers, the slab on top is more variable. The most likely places to trigger a slide are recently wind loaded slopes where the slab is thicker and more cohesive. Recent strong winds have reached below treeline and affected many slopes.

    Recent avalanche activity shows us that avalanches have gotten larger and will break 2-4 feet deep and possibly hundreds of feet wide.

    THIS AVALANCHE PROBLEM IS TRICKY - Tracks on a slope do not mean it's safe. The way this avalanche problem works is that it may be the 2nd, 3rd, or even 10th person on a slope who triggers it.

    Craig describes this set up in the video below

    Photo below from an east facing slope shows that weak, rotten foundation in the snowpack near the ground. All the snow above it is what will avalanche.

  • Wind Slabs

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

    Winds have generally been westerly, blowing from the WSW and more recently from the WNW. These strong winds have easily transported the new snow and formed fresh slabs. These slabs may cause smaller avalanches on their own. In many places these wind slabs are resting on low density snow from earlier this week and Michael J found near Hoyt Peak.

    The main issue with slabs of wind drifted snow is that they increase the load and stress on buried persistent weak layers described above which increases the likelihood of triggering a slide. Avalanches may start in these wind slabs but then step down into deeper layers in the snowpack and break of large areas hundreds of feet across.

    What's tricky - winds have reached well below treeline and you may find fresh deposits on slopes you normally consider sheltered from the wind.

    Photo of winds drifting snow yesterday. Weston reported that drifts TRIPLED in size yesterday.

Special Announcement

HEADS UP - In the last seven days in the U.S., there have been 10 avalanche fatalities - 3 skiers in Colorado, 1 skier in Colorado, 3 hikers in Alaska, 1 skier in New Hampshire, 1 skier in California, and 1 in Utah on Square Top. On Thursday, Craig, Andy, and Joey setup the avalanche beacon training park at the Nobletts trailhead. There is also one at the Bear River Trailhead that Ted Scroggin set up. These beacon parks have pre-buried beacons that you can turn on/off with a control panel. It only takes a few minutes to refresh your beacon searching skills at one of these places.

Recent Activity

Yesterday there was a large, intentionally triggered avalanche in upper Weber Canyon on a heavily wind loaded slope. This slide is a good example of what we can expect today. There have been several other similar slides this past week, several feet deep and several hundred feet wide.

There are two great obs from yesterday near Hoyt Peak and upper Weber Canyon. Both reported strong winds transporting lots of snow.

There are five great obs from Thursday worth reading. Craig was in Mill Hollow, I was in Moffit Basin, JG was in upper Weber Canyon, Ted was near Gold Hill, and M. Davis was in Soapstone. Find them here.

Snow and Weather

Nowcast-

Snow fell most of yesterday and into last night. There are only a few inches at trailheads, but about 10 inches of new snow (0.5-0.7 inches of water) at upper elevations and maybe as much as foot in some places. Strong winds blew yesterday and continue this morning. They have come from the west-southwest and currently from the west-northwest. At 11,000 feet winds are blowing 40-50 mph. At lower ridgelines, winds are blowing 10-15 mph gusting 20-30 mph. Temperatures this morning are mostly in the low teens F.

Forecast-

Today will be cold and windy with a mix of sun and clouds. High temperatures will be in the upper teens and low 20s F. Winds should increase some this afternoon and the highest locations could see gusts of 60-70 mph. Other places should have winds averaging 10-20 mph with gusts of 30 mph generally from the west-northwest.

Futurecast-

Sunday should have more sunshine, slightly warmer temperatures, and more winds but they won't be as strong. The first half of next week should be mostly dry. The second half could have more snowfall but weather models don't agree at this point with what we'll get. Time will tell.

Looking for real-time temps, snow, or wind?

Click here and then on the "western Uinta" tab for western Uinta specific, weather station network.

Additional Info

Craig will update this forecast by 7:00 AM tomorrow, Sunday, February 7th.

Your observations are import, so please let me know what you're seeing... click HERE and contribute to this amazing community based program

General Announcements

If you see or trigger an avalanche or just wanna let me know what you're seeing you can reach me directly at 801-231-2170 or [email protected]

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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