Bollettino valanghe

West Slopes North

Northwest Avalanche Center
Vedi sulla mappa

Pericolo valanghe

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

In sintesi

Avalanche danger is generally Low in places that do not have freshly wind drifted snow. Avoid steep slopes where you observe active wind loading. Wind slabs could be easily triggered in locations where they form over slick crust or weak snow surfaces.

Problemi valanghivi

  • Wind Slabs

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

    A combination of 2-4” of soft snow on the ground and strengthening northerly winds open the door to fresh wind slab formation. Wind speeds and the amount of snow available for transport vary across the forecast zone. The more new snow on the ground and the stronger the wind, the more likely you are to find a small, unstable slab. Northerly winds should mostly build fresh slabs on the south half of the compass, if you find one at all. Older slabs may exist on other aspects.

    Blowing and drifting snow will show you which slopes are building fresh slab. Pay attention to changes in snow depth and texture. Pockets of winds slab should have a smooth appearance while the surrounding snow might look roughed up or jagged. Hand shears and test slopes can help you gauge if wind slabs are reactive. 

    (1/9/2022)

    Northerly winds can strip out snow from normally wind loaded slopes as seen in this example from a previous winter.

    Photo: Andy Harrington

Avalanche Discussion

Several recent observations highlighted that more new snow fell on January 16th and in more areas than initially thought. The 4” or so of new snow sits on crust in shaded terrain also untouched by northerly winds. A stouter crust is found on sun-exposed slopes. Some low and mid-elevation areas saw enough sun for the crust to soften midday. Windward, upper-elevation slopes and ridges hold nearly every kind of wind affected snow you can think of.

Active transport and wind affected snow were noted at upper elevations on Mt. Baker on Saturday. No fresh wind slab or signs of instability were observed at mid-elevations around the Baker BC or Glacier Creek. One team on Ruth Mountain did report triggering a few very small wind slabs low on the north side of the mountain. Snowpack observations continue to yield clean but stubborn shears over the crust buried on January 10th. This crust is found anywhere from 6” to 24” down depending on elevation and exposure to wind and sun. 

While the current snowpack setup is fairly benign beyond some wind slab formation, the rapid weakening of snow from the surface down to the Jan 10th crust is noteworthy. In addition to surface hoar, cold temperatures and clear skies have enabled faceting that is even starting to eat away at some of the near-surface crusts. In previous winters, the same weather and snowpack variables have created some very large avalanches once loaded up with new snow. As usual, there is no guarantee this will happen, but it's something to keep in mind whenever we get some more snow.

Regioni coperte