Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Thursday is going to be a scorcher in the West South zone. If you are sinking into moist snow past your ankle, be leery of slopes over 35 degrees. Wet avalanches will be a focal point until temperatures cool and the snow surface freezes.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    The snow surface is expected to at least partially refreeze overnight into Thursday, possibly leading to short-lived stability in the morning hours. However, as increased sunshine and abnormally warm temperatures impact the zone, that crust may break down on slopes that receive direct sunshine.

    Continue to use the snow surface as a guide to identify areas where wet loose slides are possible. Look for moist snow deeper than your ankle and a slope angle steeper than roughly 35 degrees.

    With inversion conditions expected, slopes could be baking in the sun high above you, even if you're traveling in a cloud down in the valley. So use good travel techniques and don't turn off your avalanche brain. If you see new rollerballs, fresh fan-shaped avalanche debris, or snow shedding from rocky ledges, head for lower-angled slopes.

Avalanche Discussion

We're in a heat wave in the West South zone. Temperatures soared to over 50 degrees at almost all NWAC weather stations on Wednesday. Paradise even went above 60! Expect multiple other stations to follow suit on Thursday as we endure the warmest day of the week so far. The high clouds that have helped keep the sun's influence in check should dissipate, leaving us with mostly sunny skies. That doesn't mean some clouds won't be hanging around. Inversion conditions are expected to develop, meaning areas like White Pass or deeper valleys may be socked in, at least to start the day.

The real question becomes the overnight refreeze and the wind. We expect at least partial freezing of the surface on Wednesday night. On Thursday, easterly winds should ramp up, affecting areas closer to the crest, possibly keeping the snow surface cooler. Further west, such as on Mount Rainier or Mount St. Helens, all bets are off. There's a lot of uncertainty about how the snowpack will respond when temperatures get this hot in February. 

Loose slides remain the most likely scenario. In areas where the January Drought Interface (JDI) is stout, we expect avalanche activity to be limited to the snow about this burly crust. In areas where the JDI is not very pronounced, avalanches may gouge deeper into our thin mid-winter snowpack. Although there's not much snow left in the trees or clinging to the rocks, whatever's out there will have a good chance of coming down in the heat.

The curveballs could come from icefall high on volcanoes or other rogue events that can often occur when temps are above freezing for multiple days straight. We don't currently have the snowpack structure to make these a major concern. But keep them in the back of your mind as you make your travel plans. Unusual weather, unusual season... maybe that leads to unusual avalanches.

As has been the case all year, travel hazards are prevailing. Holes, creeks, bushes, rocks, ice, and bare ground are commonplace throughout the mountains.

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