Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

You can trigger avalanches on steep slopes where you find recent wind drifting or weak surface snow.  Expect another relatively calm day with very cold temperatures keeping the snow light and dry on most slopes. The next storm arrives on Thursday.

Problemi valanghivi

  • Wind Slabs

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

    Watch for triggering wind slab avalanches on leeward sides of high ridges and at unique locations from localized winds on the 27th. Use caution on wind-loaded slopes steeper than 35 degrees. Steer around areas of stiffer, drifted snow, deeper pillows, and wind features. To avoid these avalanches stick to windward or lower angled slopes or wind-sheltered terrain. There's uncertainty at the highest elevations where a remote chance remains for large or widely propagating avalanches on slopes that received significant wind-loading over the weekend.

    Winds on Monday and possibly Tuesday drifted snow primarily from the west and were channeled by terrain. Wind slab distribution may be uniquely isolated and less predictable than with typical wind events. Winds on Mondays were most pronounced at mid elevations near the Cascade Crest or at upper elevations further east of the crest.  The low-density snow could be easily transported by lighter-than-average wind. 

    (12/27/2021)

    Blowing snow was observed on Dec 27th in the Chiwakum Mountains on the border of the Stevens and East Central zones.

    Photo: Matt Primomo

Avalanche Discussion

You may be able to trigger small loose avalanches in the surface snow on slopes 40 degrees and steeper. Wednesday will be another relatively calm, cold day with some sun. This will be a great day to track the variety of surface conditions that have formed before they get buried by incoming snow on Thursday. Submit an observation and let us know what you see.

Since the Solstice, storms totaled over 3 feet at the top of Stevens Pass. This week, temperatures dropped to rarely seen frigid lows. Be proactive around frostbite and cold weather injuries. The snow is deep, and observers have reported the potential for snow immersion hazard. Stay away from tree wells and keep your partners within sight and voice contact.

The last round of avalanches occured through the weekend. On Monday, an observer on Big Chief Mountain triggered a small wind slab avalanche near treeline on a northwest aspect. Observers reported natural avalanches that likely ran between the 25-26th including a notable  (D3) avalanche that broke widely across alpine terrain on a NE aspect of Mt Mastiff (see photo below). On Saturday, observers on Arrowhead Mountain triggered a number of reactive, but small, storm slab avalanches. Most observations since the weekend indicate that storm interfaces are bonding well.

The most pertinent recent observations focus on surface conditions and locations of wind slab development. On Tuesday, observers reported very large surface hoar (2cm) with nearby wind-sculpted surfaces on the ridge of Big Chief Mtn (see photo below). Another observer on Lichtenberg Mtn found large surface facets over a thin crust on a south aspect at 5,000ft. A number of crusts may be found in the mid and lower snowpack from early to late December. The Solstice crust is thin and can be found about 2-3 feet below the surface. It's worth monitoring this crust with snowpack tests, especially if you are venturing to upper elevations or traveling on the eastern end of the zone.

 

Regioni coperte