Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Open full map
Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

An incoming storm should deliver low-density snow and some gusty winds to much of the West South on Tuesday. You should steer around unstable pockets of wind-drifted snow near ridgelines or rocky features where triggering an avalanche is more likely. If you notice red flag signs of stability such as shooting cracks or fresh avalanches, seek out more wind-sheltered terrain.

Problemi valanghivi

  • Wind Slabs

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

    Wind-loaded terrain at mid to upper elevations will be the most likely location for you to trigger a slab on Tuesday. Actively blowing snow can help you identify where shallow Wind Slabs may be forming. Other visual clues such as fresh drifts behind natural objects or textured surfaces are indicators that the wind has affected the snow in that area. We expect any potential Wind Slab to be on the small side, but the bonding may vary from slope to slope based upon the prior snow surface. Take some time to check the base of the new snow to see how it has bonded by using quick hand pits or test slopes as you travel. You should steer around steep features over 35 degrees that you suspect are wind-loaded or if the new snow has not bonded well to the underlying surface.

    (3/5/2022)

    This shallow slab was found near Paradise over the weekend. If winds are able to transport snow on Tuesday, similar slabs could develop on leeward slopes.

    Photo: Public Observation

Avalanche Discussion

Tuesday will bring a return to snowy and windy conditions in the West South, with increasing snow intensities throughout the day. In a bit of a wrinkle, this storm favors the crest over the volcanoes and could deliver higher snow totals to areas such as Crystal and White Pass. While the water numbers aren’t impressive by Cascadian standards, we do expect higher than usual snow to water ratios, and a bit of wind should be enough to create some avalanche potential on steep features. 

This change to new snow problems comes after a week of dealing with primarily wet avalanches. Last week’s atmospheric river event dropped up to  7.5” of water within the zone, resulting in a significant avalanche cycle. A few inches of cold dry snow fell in the days that followed and was weakening (faceting) on shady slopes over the weekend. The effects from this time period are still visible throughout the zone with avalanche debris, open creeks, rain runnels, and a variety of snow surfaces. 

Why is this important? These various, and in places rough, snow surfaces will help dictate the ability for avalanches to fail in the coming days. In areas where the new snow is poorly bonded or overlaying weak snow, such as on shady slopes, slabs could be more touchy. On the flip side, if new snow is falling on a pile of hard avalanche debris, you’ll be hard-pressed to get a new slide going. On slopes where a firm smooth crust exists, such as on slopes that see direct sunshine, a poor bond could mean that dry loose avalanches composed of the new low-density snow are able to run far and fast. Even if we hit the high end of our water numbers, we’re not talking about a lot of accumulation. So taking a moment to look at the bond and previous snow surface on the slope you are traveling shouldn’t take too long and will help you make a better slope-specific forecast. 

Additionally, this storm shouldn’t be enough to bury all of the natural hazards that the atmospheric river exposed, so tread carefully and don’t get tripped up in consequential terrain.

Regioni coperte