Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

Sun
Alpine
1 · Low
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Another spring-like day may lead to wet snow avalanches as the temperature warms. Choose lower-angle slopes or move to a shady location if you are sinking into mushy snow. A surface slide or cornice fall could trigger a larger avalanche on buried weak layers.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Today is the third consecutive day of warming temperatures and sustained sunshine, resulting in a Wet Loose problem. Fortunately, modest daytime highs and well below-freezing readings overnight have limited wet snow instabilities to the near-surface on aspects facing the sun. 

     A surface crust of varying thickness is found on sunny slopes up to 7000 feet or higher. As the crust deteriorates through the day, the danger will rise. Shady slopes harbor loose, dry snow, which has so far escaped warming. If today's warming exceeds forecasted readings, wet loose activity may develop on aspects not receiving direct sun.

    The threat of natural Wet Loose avalanches on sunny slopes below 7000 feet is diminishing but triggering a slide in mushy surface snow remains likely as the day heats up. A crust that cannot support you or your machine indicates instability. Rollerballs and pinwheels are precursors to a wet slide. If you can make a snowball in the surface snow, this signifies that the surface has become moist. These are signs directing you to move to a different aspect. Stay ahead of the sun today, or select lower-angle slopes to enjoy the corn-like conditions. Choose a route that does not expose you to steep overhead westerly aspects on your exit. Limit time above terrain traps where even a small slide can pile up deep. Northerly aspects should remain safer and hold higher-quality snow.

     

    (1/8/2023)

    Small rollerballs due to the warming of the surface snow.

Avalanche Discussion

The transition to a spring snowpack has been slow and steady. Warming last weekend and earlier this week developed the first Wet Loose avalanche problem since mid-January. Following a mid-week cooling, we're back with an extended run of wet snow instability. Fortunately, Colorado-like temperatures have been teleported to the Flathead, resulting in, so far, relatively minor wet avalanche problems. Daytime highs are above-freezing at upper elevations, but well-below-freezing temperatures overnight are limiting the hazard.

Temperatures last night were not quite as cool as previous nights. Especially near the Continental Divide, where this morning's temperatures at Marias Pass are 20+ degrees warmer than this time yesterday. Readings from the east side of Glacier are at or above freezing. There is a chance that the wet snow hazard will increase at upper elevations in locations experiencing this relatively warm air.

We are concerned about when the big warm-up occurs due to the generally soft snow found in the lower reaches of avalanche tracks. This season's colder-than-normal conditions resulted in lower-density snow and far fewer rain events than we are used to in soggy NW Montana.  When the inevitable above-freezing temperature around the clock occurs, large destructive wet slides are expected as debris from above gouges down into the soft snow, possibly removing the entire seasonal snowpack.

There were zero public observations submitted Friday, so our data is a bit limited this morning. I visited Elk Mountain to take a closer look at a Persistent Slab avalanche first reported by the BNSF avalanche safety team Thursday. This slide failed on a 40-degree slope at 6600 feet. The central portion of the crown was over 6 feet deep but tapered to around 1.5 feet deep into rocks on either end. We believe the slide initiated in the rocks where the weak snow from November was closer to the surface.

FOFAC Event: March 30th, 2023– Whether you're chasing tan lines, big lines, or both, you'll learn something valuable from FAC Lead Forecaster Mark Dundas about spring avalanche problems, how they differ from winter problems, and how to manage them. We will also discuss current conditions and concerns (or lack thereof!) with our spring snowpack. Enjoy a cold brew from Bias Brewing and a scoop from Sweet Peaks Ice Cream.

The event is free and open to everyone. Begins at 6 pm.

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