Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Wind-affected snow exists in widespread areas near and above treeline. Before entering larger terrain features, use simple slope tests and hand shears on similar aspects to check reactivity. Steer around steep slopes where you find actively drifting snow.

Problemi valanghivi

  • Wind Slabs

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

    Wind-affected terrain exists in wide swaths of the zone, but a lack of recent avalanche activity suggests that most slabs may be stubborn to trigger. A fresh round of wind transport late Wednesday night and early Thursday will maintain or build the danger slightly. Watch for signs of active snow transport to identify wind-loaded areas where you are most likely to trigger an avalanche. Cracking surfaces or hollow-feeling snow layers should put you on alert. If you encounter wind-affected snow, try assessing it with simple hand shears. If the new snow slides easily off the underlying surfaces, or you can get shooting cracks on small test slopes, it is probably time to move to lower angle terrain. 

    Easterly winds Monday and Tuesday have transported snow onto westerly aspects. We're uncertain how much these winds affected the majority of the East Central zone. You'll have to do some detective work to identify clues. Cornices form with the prevailing wind direction, and wind slabs from Easterly winds may form on the opposite side of the ridge with sharper cornice lips. Elevated danger may linger in the Wenatchee Mountains where strong to extreme NE winds blew low-density snow onto atypical aspects through Tuesday night. In these areas, the strong winds might have dragged wind slabs down into the NTL or even possibly exposed BTL locations. Shallow snowpacks in these areas increase your risk for trauma.

     

    (2/23/2022)

    Cracking in skin track SE at 6800ft. Fortune Creek Drainage.

    Photo: Matt Primomo

Avalanche Discussion

NWAC forecasters traveled in Fortune Creek on Thursday. They found a lot of wind-textured snow on all aspects near and particuarly above treeline. Slabs were generally small (4-12" thick) and stubborn, but in isolated locations, slabs were up to 1.5 ft thick. They observed cracking snow surfaces up to 6 ft in length from the skin track indicating that these slabs may still be reactive. They found 16" of snow atop the Valentine's day crust that was well bonded on S aspects, but with the crust breaking down into weaker facets on N and E aspects and exhibiting a high degree of variability. This may not be a problem with the current low-density snow on top, but it is something to watch going into future loading events.

Snow accumulations tapered quickly from west to east in the zone. Expect a range from 20" near the Cascade Crest to under 10 inches further east. Mission Ridge only receiving around 5-6" of low-density snow. While most reports suggest the snow has bonded well to the 2/19 crust, a recent report from the western portion of the Icicle Drainage found some tendency for propagation on this interface. However, given a lack of reported avalanche activity, we think the chances of triggering an avalanche down to the 2/19 interface is very low. Given the wide variability throughout the zone, approach new terrain with caution and make observations as you travel.

Unusually cold temperatures may make slabs behave in ways you might not expect. It has also slowed the impact of the sun on southerly aspects. An isolated size one loose avalanches were observed in Fortune Creek on Thursday, running 500-600 feet on a very steep S aspect. Most loose avalanches were initiated by melt off small rocks and cliffs and entrained dry snow, but were very small. We are moving towards the end of February, and the sun is increasing in intensity, so anticipate isolated loose avalanches on very steep slopes in direct sunlight. If rocks, trees, or cliffs start shedding snow or ice, you may want to make your way to shadier or lower angle terrain. On shady slopes, cold clear nights may begin to weaken the surface snow and you may also be able to trigger small but fast-moving dry loose avalanches. 

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