Bollettino valanghe

West Slopes South

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Stay vigilant near convex features or rocky terrain such as chutes and cliffs where you could trigger wind-drifted pockets of unstable snow on Wednesday. As we march toward springtime, sunshine will become more of a player and could help induce small slides on steep slopes.

Problemi valanghivi

  • Wind Slabs

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

    An uptick in winds on Wednesday afternoon could be enough to create a fresh round of Wind Slabs for you to manage as you ascend in elevation. They could intermingle with existing slabs formed due to windy weather in recent days. Since the wind direction has been flip-flopping this week, you could find them on a variety of aspects. You should be able to use visual clues such as blowing snow and fresh drifts to help identify newly forming slabs. You may need to feel for differences in the density of the snow as you travel to help pinpoint older ones. Regardless of their age, you’re more likely to encounter wind-drifted pockets near rocky features such as confined gullies or the base of cliffs, on convex rollovers, or the leeward side of ridgelines. If you suspect a slope to be wind-loaded, steer around it.

    (2/28/2023)

    A shallow skier-triggered slab avalanche in a steep confined gully. This slab was intentionally triggered by Crystal Mountain Patrol on 2/28.

    Photo: Crystal Mountain Pro Patrol

  • Loose Wet

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

    With cold dry snow in place and the sun expected to come out for a few hours tomorrow, we can’t rule out some solar-induced loose avalanches. For this one to pan out, March sunshine will need to overcome cold temperatures combined with increasing winds and clouds throughout the day. If it can, you could see snow start to shed from rocks and trees, triggering avalanches on the slopes below. The moisture content of the snow may be somewhere between Wet and Dry, but the behavior should remain the same. These avalanches should start at a point and fan out as they move downhill. While many travelers regard loose avalanches as easy to manage, be sure not to get surprised by one near a terrain trap. Choose travel routes where you can stay aware of steep slopes receiving direct sunshine above you.

    (2/11/2023)

    Example: small loose avalanches originating near rocks and trees. These occurred on sun-exposed slopes the day after a storm a few weeks ago.

    Photo: Andy Harrington

Avalanche Discussion

Wednesday should be a quick reprieve from the recent stormy weather that has dropped over a foot of snow around the West South zone since 2/25. Expect morning sunshine worthy of the first day of meteorological spring. As the day progresses, winds and clouds should increase ahead of our next snowy period. 

The recent storm focused on the southern half of the zone and volcanoes, but even areas that were not favored such as Crystal Mountain still picked up around a foot of snow. The new/old (2/25) interface is variable across the zone, but in most locations, you’ll encounter some sort of crust to help mark the transition point. On Monday, NWAC forecasters found that the bond at this interface was poor near Crystal Mountain. On Tuesday, Crystal Mountain Pro Patrollers reported easy to trigger soft slabs (3-8" deep) with ski cuts during their mitigation efforts. Avalanche professionals near White Pass relayed their findings of a moderate bond at the 2/25 interface (1.5 feet deep) and plenty of signs of wind-effected snow on a variety of aspects. We do not have much information at this time from the volcanoes where more snow has fallen (1.5-2 feet).  If you're planning on heading to one of our southern volcanoes, you may want to check out the Hood forecast for more information about how this storm has stacked up. 

We don’t envision much change on Wednesday, except you could see the snow start to “slab up” a bit more if the sun stays out for a prolonged period of time. Any triggered avalanche has the potential to run far and fast at the 2/25 interface, but we do not anticipate any deeper slides at this time.

Regioni coperte