Bollettino valanghe

Bollettino valanghe

Payette Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New snow and moderate winds will build fresh wind slabs throughout the day today. Expect to find these fresh wind slabs in the middle and upper elevation on leeward terrain features. The new snow will likely not bond well to the previous crusts and firm snow surfaces. Pay attention to dry loose snow moving on these slick snow surfaces. Snowfall and wind are forecasted to increase today. Expect the avalanche hazard to increase as well throughout the day.

Problemi valanghivi

  • Wind Slabs

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

    The wind slab problem from our snowfall last week is becoming unlikely. However, wind slabs should be at the forefront of your mind today with several inches of new snow forecasted and moderate southwest winds. Compounding this hazard are the slick surfaces that are present on many different aspects. New snow, especially wind-driven snow will have a difficult time bonding well to the previous snow surface.

    Wind drifts indicate the presence of wind slab formation on leeward terrain features.

  • Loose Dry

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

    Small loose dry avalanches or sluffs could run with you in steep terrain. This morning you are most likely to encounter this problem in north-facing terrain. As snow accumulates throughout the day, expect to find dry loose avalanche problems on other aspects that formed a firm snow surface (like solar aspects with a melt-freeze crust). 

    (2/19/2022)

    Shaded, protected north-facing slopes

    Photo: PAC

Avalanche Discussion

Today's advisory is sponsored by Mile High Powersports in McCall. Thank you for supporting the Payette Avalanche Center.

We are in transition yet again in the West Central Mountains. Monday/Tuesday we received 2-4" of snow that fell on a variety of crusts and firm snow surfaces. Wednesday we got another round of 3-6", mostly in the northern portion of our advisory area. Thursday through Saturday was dry and warm. We saw failures of the new snow on the widespread crust that was buried on 02/14. We've also seen the warming of that new snow and point releases on solar aspects. Today a low-pressure system moves into our region and we're forecasted to see 2-4" in the mountains with higher amounts possible, especially in the northern portion of the zone.  Avalanche activity will increase with this storm as will the likelihood of human-triggered avalanches.  It is going to be important to pay close attention to the snowpack and adjust your terrain selection accordingly.

 What to watch for:

  • New snow problems: Several inches of new snow today into tomorrow with moderate southwest winds will create fresh wind slabs in middle and upper elevation terrain. This new snow may have the potential to create storm slabs in wind-protected locations below 7000'. Aspects that face southeast through southwest have formed a surface melt-freeze crust during the past two days. This new snow will likely not bond well to the older snow surface of certains aspects and may easily trigger small avalanches.
  • 02/14/22 Crust: Last Monday a storm buried a widespread crust throughout our advisory area. In some locations this was a stout melt-freeze, in others, it was a softer rain/humidity crust. Either way, we have a buried crust that is preserved and showing up in snowpits throughout our region. Expect this layer to be problematic as we add more weight to the upper portion of the current snowpack.

How to mitigate these concerns:

  • Pay attention to the new snow and how it's bonding to the previous snow surfaces on different aspects. Where were previous firm snow surfaces? Upper elevation wind-effected terrain, aspects that face the sun. Avoid slopes steeper than 30 degrees in these locations.
  • Listen to feel the new snow. Are you hearing whumping or collapsing of the snowpack? If you are, you are possibly triggering a persistent weak layer and/or the 02/14 crust. Stay away from steep slopes if you're getting this feedback from the snowpack.

 

*** Check out our Observations Page to see what others are seeing...We are always looking for more Information from snowmobilers and skiers on snow and weather conditions. These observations help our forecasts and they help other users in and outside of the community. It can be quick with or without a photo…Use the Observations link at the top of the page to submit your observations. 

***Motorized users, please be aware that there are some areas of the Payette National Forest that are closed to motorized use, some of these closures are to protect wildlife and some are to protect other recreators.  Check out the Winter Travel Map below for details

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fseprd891395.pdf