Bollettino valanghe

Gunnison

Crested Butte Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Up to a foot of snowfall and efficient winds formed sensitive drifts on leeward terrain features at upper elevations.  Carefully observe loading patterns to identify and steer around drifts.  Easterly aspects below ridgetops and cornices are the most likely locations to encounter a sensitive drift.  Loose snow avalanches could be possible on steep slopes particularly at low elevations due to warm temperatures and possibly sunny slopes at higher elevations if the sun comes out.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–1.5

    Moderate winds with strong gusts from the west and northwest have drifted the recent storm snow to leeward terrain features.  Easterly aspects are the most likely place to encounter a fresh drift.  Most old surfaces are comprised of slick crusts which may not bond well with the storm snow.  Fresh drifts can be found below ridgetops, underneath cornices, and cross-loaded into gullies.  Shooting cracks are a clear sign of sensitive conditions.  Carefully read the terrain to identify drifted features and steer around them to reduce your chance of triggering a Wind Slab.

    A wind slab from a few weeks ago.  Avalanches might grow larger than the one pictured here but expect to find them in similar types of terrain.

    Photo: Evan Ross

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Up to 12 inches of storm snow may easily shed off steep slopes as temperatures warm throughout the day particularly at lower elevations.  Periodic sunshine may also heat the recent storm snow on sunny slopes.  Pay attention to the feel of the new storm snow.  If you notice it becoming thick, sticky, or moist then expect that you can trigger a loose avalanche.  If the sun comes out for an extended period, steep sunny features may naturally shed.  You can use sluff management techniques to handle loose avalanches or move to lower-angled terrain.

    An example of moist and sticky storm snow becoming a loose snow problem.  Roller balls and pinwheels are clear evidence of the problem.

    Photo: Zach Guy

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    High-consequence persistent slab avalanches have become isolated and difficult to trigger.  The most recent Persistent slab avalanche was observed on 4/14 near Avery Peak before that was 4/3 on Mount Whetstone.  The most problematic terrain is on high elevation, northerly aspects in areas with relatively shallow snowpacks (<175 cm).  Old facet layers are weaker and easier to impact in steep rocky slopes with variable snow depths.   This video highlights this type of terrain. 

    (4/14/2024) A recent Persistent Slab on a northwest aspect near Avery Peak.  

    Photo: Crested Butte Avalanche Center

Avalanche Discussion

Storm totals vary across the forecast zone.  Areas near the town of Crested Butte at valley bottom have just a few inches, but areas to the west and north of town recorded nearly a foot of snowfall.  An additional few inches may accumulate during the first half of Tuesday.  Locations with the most are Irwin and Purple Ridge with lesser amounts elsewhere.  Expect to find greater avalanche hazards where the most snow falls.  You can also expect a marked increase in storm totals as you climb higher in the terrain.

There are two primary problems to manage today with the storm snow.  First, expect to encounter sensitive soft slabs on leeward terrain features where gusty winds drifted the new snow.  The new snow fell on slick crusts so expect poor bonding at the old snow interface.  Avalanche size will commonly be small, but some long slopes or features with a big fetch could produce a large avalanche.  A reasonable gauge for increased hazard would be finding 10 or more inches of new/drifted storm snow.

The second issue with the storm snow comes from warming temperatures and possibly sunshine.  Low-density storm snow often produces 'shed' cycles if warmed rapidly after a storm.  This problem is most likely at low elevations where temperatures will climb above freezing however it might extend to higher elevation slopes on the south half of the compass if the sun comes out for an extended period.  Most loose avalanches will only involve the recent storm snow and slide on the crusts below.  There is a chance that some very low-elevation slopes have a very poor freeze beneath the storm snow and a loose avalanche could possibly entertain older, wet snow.

 

 

Regioni coperte