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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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A buried persistent weak layer remains surprisingly reactive and human triggered avalanches breaking several feet deep are LIKELY, especially on slopes facing the north half of the compass near and above treeline. In terrain with these characteristics you'll find CONSIDERABLE avalanche danger. MODERATE avalanche danger is found below treeline and human triggered avalanches breaking to this weak layer are POSSIBLE.

South and west facing terrain has been cooked by strong sunshine, but will heat up fast this morning. As the snow becomes damp, the danger rises to MODERATE for wet loose slides and sluffs. These should be relatively small and occur predictably as the day progresses.

Scroll to the bottom for a note on slope angle and how to have a blast without entering avalanche terrain.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    4

    We can expect more of this today. The avalanche on this upper elevation northeast facing slope was initiated by a small piece of snow releasing on a steep, rocky face near the ridge, which then triggered a much larger slide as it crashed onto the slope below.

    A persistent weak layer (PWL) of weak, faceted snow is buried 1-3 feet deep. It's hard to believe that this layer is still alive and well, lurking in the snowpack, despite such warm weather. When you see it and feel it, it's almost shocking how dry and loose it is (like a layer of shugga... baby :). The snowpack continues to show us that this layer will fracture and produce avalanches.

    Where does it exists? It is widespread on NW-N-NE-E facing slopes near and slightly below treeline. Above treeline in alpine terrain, it's distribution is more pockety.

    What will the warm weather do? For now, "all bets are off" and conditions remain dangerous. In the long run, the warmth will help this layer slowly heal. The wild card is that if there's enough heat to melt snow and cause liquid water to percolate down to this layer, then avalanches would start happening on their own.

  • Loose Wet

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

    Strong sunshine, very warm air temperatures and a marginal overnight refreeze, conspire to quickly soften the snow on sunny slopes. And while this terrain has experienced several melt-freeze cycles and you may find some decent, supportable corn snow, it'll be short-lived. As the snow becomes damp, small wet loose avalanches may occur this afternoon, but I don't expect them to be a widespread issue in the Uinta's that tend to stay a little cooler than the Wasatch Mountains.

    Look for snowballs rolling downhill with increasing frequency as a sign of unstable snow. Typically they happen near exposed rocks or cliffs that absorb extra heat from the sun and reradiate that heat into the surrounding snow.

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Recent Activity

Yesterday, avy pro Dave Kikkert captured the image above of a natural avalanche in Upper Weber Canyon and comments... "Natural that occurred between 10 and 11 am due to heating. It confirms what we have been finding: where the persistent slab problem exists (more sheltered northeast-north facing slopes), it is still quite reactive. Would expect similar in the next couple days with continued heating."

Your input is vital and we're interested in what you're seeing. Please contribute to this great community resource and go here to fill out an observation.

Snow and Weather

NOWCAST-

Partly cloudy skies allowed some cooling overnight, but let's face it... early morning lows with temperatures in the mid to upper 30's is downright tropical for the Uinta's in late March. Along the high ridges. southwest winds blow in the 20's and 30's. Overall, the snow took a hard hit yesterday with low elevation terrain getting smoked and rapidly evaporating. However, with a little hunting you can still find hot pow on upper elevation north facing slopes and I think a short-lived window of supportability exists on the sunny terrain, but it's gonna go fast today.

FORECAST-

Look for sunny skies with high temperatures soaring into the 50's. Southwest winds blowing in the 30's and 40's near the high peaks are gonna be a nuisance this morning, but decrease as the day wares on. Expect partly cloudy skies overnight with temperatures dipping into the mid 30's.

FUTURECAST-

Record-setting temperatures continue through Sunday, but the leading edge of an upcoming storm delivers increasing clouds late in the day. Monday is a down day with storminess developing Tuesday. Unfortunately the storm looks underwhelming, though we might be able to squeak 3"-6" out by Wednesday morning. There's potential for another system on Thursday.

Mark rode with the crew from Utah Division of Recreation, touring around the Mirror Lake Highway. It was a little tough keep the sleds cool in the morning on refrozen snow; otherwise, it was a great day to be out looking at avalanche conditions. Photo above is from the east side of Bald Mountain.

Trip reports and snowpack observations are found HERE.

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

AVALANCHE TERRAIN:

Slope angle determines where avalanches can happen and where they can't. Generally, any slope steeper than 30 degrees is where avalanches occur. This means all you need to do is ride slopes less than 30 degrees in steepness and you'll never have to deal with avalanches.

There's a catch! You can't be underneath slopes steeper than 30 degrees either, even if you're on a flat slope, because avalanches can crash down on you. It turns out that skiing or riding slopes about 25 degrees in steepness is really fun and even more fun because there's no worry of avalanches. Unfortunately, it takes a lot of practice to estimate slope angles with your eyes alone. The way to get practice and the only way to know for sure is to measure slope angles with slope measuring tool shown in the photo below, and Toby describes it in this video. There are also many apps so that you can use your phone in a similar manner.

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

General Announcements

The information in this forecast expires 24 hours after the day and time posted, but will be updated by 07:00 Sunday, March 27th.

Before it gets too crazy, now is the time to book an avalanche awareness presentation for your group, club, or posse. 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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