Bollettino valanghe

Northwest Mountains

Crested Butte Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

8" to 10"+ of new snow has increased the danger today.  Today's avalanche problems will generally be confined to the fresh snow that has accumulated over our dust/crust layer.  Instabilities are most likely to be found on high-elevation, leeward slopes where winds are forming thicker slabs.  The new snow may also begin to shed as wet sluffs from sunbaked slopes as cloud cover diminishes and temperatures warm up today.   Use caution in consequential terrain where a shallow avalanche could cause harm.  

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    8" or more of new snow and moderate westerly winds have formed fresh wind slabs in high elevation, leeward terrain.  Northwest winds today will expand the distribution of the problem to more slopes today.  Look and feel for signs of recent drifting to identify features of concern:  slabs will look and feel thicker.  They'll be most common below high ridgelines or in cross-drifted gullies or rollovers.   You can avoid the problem in wind-protected terrain.  

    Example of a small wind slab that formed on the lee side of a ridgeline earlier this winter. 

  • Loose Wet

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

    As the new snow moistens and gets sticky on sunbaked slopes, it could produce natural or triggered sluffs running above the dust layer.  They'll be most dangerous in high-consequence terrain above cliffs, trees, or gullies.   If the snow surface starts to rollerball, pinwheels, or produce natural sluffs, use sluff management techniques or move to lower-angle terrain.  You can can avoid the problem on colder aspects where the snow stays dry.  

    If the snow surface gets wet and sticky, you'll be able to trigger shallow sluffs like this in steep terrain. 

Avalanche Discussion

We are so excited to see our mountains turn white again with a much-needed surface refresh over our dust layer!  Stations in the Northwest Mountains show 8" to 10" of new snow, and I expect a foot or more in the alpine.  CBMR picked up 7",  and as you move south and east through our Southeast Mountains, storm totals diminish.  The textured snow surface left behind by our dusty melt-down should be favorable for bonding except on high northerly aspects or where drifting snow smoothed out a fresh bed surface for wind slabs to form on.  Last night's winds were transportable out of the southwest and west, and should continue to drift snow as they shift to the northwest today.  Slabs have the potential to be larger in the snow-favored alpine of the Northwest Mountains on terrain features with large fetches.  Elsewhere, most wind slabs will be small in size.    

Today's surface refresh means there's now dry snow available to shed above the dust layer once it gets wet.  I expect today's colder temperatures and some cloud cover will help limit activity to the hottest, rockiest slopes.  Tomorrow, wet loose instabilities become more widespread with temperatures rising 10 degrees higher.  These wet avalanches will involve just the new snow and will be smaller and more manageable than the deep, gouging wet loose activity that we saw last week.  The exception would be if you find a slope where the storm interface has not frozen into a solid crust, and surface sluffs start plowing deeper through older saturated snow.  We anticipate that last night's cold temps put that issue to bed.  

We've removed cornice falls as a problem now that the major warmup has passed, but it is something that you should continue to manage for the remainder of spring.  Although cornice activity will diminish with a return to more seasonable temperatures, cornice falls will remain a low-likelihood threat on slopes with overhung cornices for the foreseeable future, exacerbated during warm-ups.    

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