Bollettino valanghe

Mt Hood

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Large, stubborn wind slabs linger on steep and unsupported lee slopes, particularly at upper elevation. Overlapping wet avalanche problems may be more obvious as snow surfaces destabilize. Natural or human-triggered wet avalanches are possible within 6" of moist, sticky snow on a firm crust. 

Problemi valanghivi

  • Wind Slabs

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

    Dense wind-affected snow from Wednesday's storm is widespread at mid and especially upper elevations. Fresh wind slabs formed from about 4" of snow over the 2/21 crust. Mild temperatures on Thursday are helping heal these slabs, but we think they have enough legs on Friday for continued caution given the large, productive slabs triggered in mitigation work at Mt Hood Meadows. Moving forward, slabs will focus on colder, shaded aspects and upper elevation lee slopes where the reactivity persists longer. Steer around slopes 35 degrees and steeper, including convex rollovers where you anticipate 6" or deeper drifts over the crust. When in doubt, you can stick to wind-scoured areas or lower-angle terrain to avoid the problem. 

     

    (2/22/2024)

    Large wind slab avalanche triggered at middle elevation in mitigation at Mt Hood Meadows.

    Photo: Joe Dellaporta

  • Loose Wet

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

    As freezing levels rise above 7000 ft on Friday, they'll destabilize any previously dry snow in less wind-affected areas. At middle elevations, you might find crusts breaking down on the southern half of the compass with previously dry snow warming onto shaded aspects as the day progresses. At upper elevations, steep, rocky features will warm up more rapidly and may destabilize shallow snowpack areas. Signs of the developing problem include rollerballs, fresh wet loose avalanches, notice crusts breaking down, or encountering wet, sticky snow. Reduce your exposure to steep slopes, including those above you. These slides may start slowly but could become large and powerful where 6" of snow sits above the 2/21 crust. Consider terrain traps such steep canyons, exposed waterfalls, and creek beds where even a small avalanche could bury you.

    (2/22/2024) Photo: Joe Dellaporta

    Rollerballs serve as your reminder to seek cooler, shaded aspects or lower angle slopes.

Avalanche Discussion

Snowfall accompanied by moderate winds brought around 4" of snow to Mt Hood Wednesday and Wednesday night. Thursday featured mostly sunny skies. Professionals in the Timberline area found touchy, small wind slabs and shooting cracks at middle elevations with more stubborn slabs at higher elevations. Wind-affected snow was widespread. Mitigation at Mt Hood Meadows produced 4-5 avalanches in the D1.5-2 range (large). 

On Wednesday, professionals in the Timberline area were able to trigger shallow wind slabs averaging about 6" but up to 1' deep above a new crust on Wednesday afternoon.  As they traveled into the upper elevation band, they observed shooting cracks in freshly drifted snow and wind-scouring along windward ridges.  

NWAC forecasters and Mt Hood climbing rangers were in the Vista Ridge area on the N side of Mt Hood Tuesday.  They observed significant wind transport and blowing snow above 6500' that increased on the upper mountain as well as touchy shallow wind slabs.  The snow was heavy and moist below 6000' with evidence of older rollerballs and wet loose avalanches.  They found 2-3ft of well-settled and bonded snow at mid-elevations above the early February crust (EFC) on this side of the mountain.  In isolated areas, a layer of weak snow grains was found above the EFC.  We don't expect any avalanches down to the EFC, but it's worth tracking with more impactful weather likely next week.   Over the last week, a steady stream of small storms and varied wind directions gradually piled up about 2ft of snow since 2/14 and built wind slabs on a variety of aspects.  

Don't forget about open creeks and waterfalls if you travel at lower elevations where we generally don't expect enough snow above the 2/11 crust for consequential avalanches.

Regioni coperte