Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

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

The avalanche hazard will increase with afternoon sunshine. Don't be caught off guard by pockets of wind-drifted snow. Plan your tour to avoid steep slopes that face south and west. Rollerballs and moist surface snow will be your cue to move to shady aspects.

Avalanche problems

  • Loose Wet

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

    Recent snowfall has left several inches of fresh snow at mid and upper elevations. Today's warming and afternoon sunshine may moisten the surface snow and initiate wet avalanches. Natural and human-triggered avalanches are most likely on steep slopes that face the sun. These slides commonly initiate near darkly colored rocks, fanning out and collecting snow as they go. Wet loose debris can travel quickly on the underlying crust beneath the new snow. Large slopes can produce avalanches big enough to knock you off your feet and carry you to places you don't want to go. 

    Rollerballs and pinwheels are precursors to a wet slide. Pay attention to how sticky the new snow is becoming. 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. Plan a route that does not expose you to westerly aspects on your exit. Limit time above terrain traps where even a small slide can deeply pile debris. Northerly aspects should remain your best bet for higher-quality snow.

    (3/13/2023) March 13th, 2023: Debris from the Jakes avalanche. Photo: Adam Clark

  • Wind Slabs

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

    Recent light snowfall and southwest winds formed thin slabs which may be reactive to the weight of a rider. Rob and Cam were outside Swan Lake and found touchy pockets of wind-drifted snow and blowing snow yesterday at upper elevations. Wind speeds at the Aeneas Ridge weather station included 15 hours of winds strong enough to drift snow throughout the day yesterday. 

    Expect wind slabs to be thickest, widest, and most common at upper elevations. To identify places within the terrain that may hold wind-loaded drifts, look for pillows or dune-shaped features near ridgelines, cross-loaded gullies, or around the sides of chutes. While choosing terrain, think of the consequences of being knocked off your feet, dragged into a tree, or pushed over rocks. You can avoid the problem by choosing terrain where the snow is sheltered or being scoured by the wind.

Avalanche Discussion

Today's high-pressure system has the potential to add a strong dose of solar radiation along with gradually warming air temperatures. Sunny aspects will likely increase surface instabilities, and we will swap most of our wind slab problems for loose wet problems. Yesterday (Wednesday) FAC Director and BNSF Safety Team toured in southern Glacier National Park and found snowpack conditions below 5000 feet ripe for wet snow instabilities. Today's gradual warming is expected to limit such conditions. However, Friday's forecast of continued high pressure may be a different story.

In the Swan Range, FAC Forecasters triggered small, soft wind slab avalanches and shooting cracks in drifted snow above 7000 feet. We anticipate that a continued wind slab problem will remain in the Swan, with 6 to 8 inches of new snow available for winds to transport at upper elevations.  

Given the sunny weather and diminishing clouds, it is worth considering your exit plan today, as temperatures will peak in the afternoon, just in time for your descent to lower elevation slopes. Although temperatures will be moderated by a mix of morning clouds, be mindful of the potential for solar radiation to overperform the forecast and thus increasing the chance of more loose wet activity on southern and western slopes. Build a margin of safety into your tour plans by avoiding travel under steep sunny slopes this afternoon. 

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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