THIS AVALANCHE FORECAST EXPIRED ON March 13, 2019 @ 11:24 pm
Avalanche Forecast published on March 13, 2019 @ 6:24 am
Issued by Clancy Nelson - Flathead Avalanche Center

Whitefish Range
Swan Range

How to read the forecast

New slabs, up to a foot or more thick, may bond poorly to the underlying snow. Use caution on slopes steeper than about 30 degrees. Track new snow totals and look for recently drifted snow. Slabs thicker than about 8” can be dangerous. Use extra caution below ridgelines and near crossloaded features. Choose simple, sheltered terrain to stay out of harm’s way.

3. Considerable

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Above 6500 ft.
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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5000-6500 ft.
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

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3500-5000 ft.
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
  • 1. Low
  • 2. Moderate
  • 3. Considerable
  • 4. High
  • 5. Extreme
Avalanche Problem 1: Storm Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Keep it simple today. Up to a foot of new snow has fallen and drifted onto a variety of weak surfaces. Crusts, facets, and surface hoar that developed over the weekend can inhibit the bonding process. Slabs can break over a foot deep where the most snow has accumulated. On steep slopes near and above treeline, watch for shooting cracks as red flags. Use extra caution on easterly slopes where recent drifting has deposited the thickest slabs. Opt for lower-angled, sheltered terrain. Avoid riding above terrain traps where even smaller avalanches will have increased consequences.

Forecast discussion

Up to 12” of new snow fell overnight, with an additional few inches expected today. Shifting winds have trended down overnight, but were strong enough to drift snow into cohesive slabs through yesterday afternoon. We were able to trigger a small wind slab at middle elevations in the Jewel Basin yesterday.

New slabs have developed on top of a variety of weak snow surfaces. Observers Monday found facets, crusts, and surface hoar across the area. New snow may bond poorly to these layers and be sensitive to the weight of a rider or snow machine. Expect slabs to be larger and more dangerous where they are thickest. The Swan and Whitefish Ranges have received the most new loading. Noisy Basin is reporting 1.4” of SWE and Big Mountain reporting 0.9” as of 5am. Stations near the Divide are showing up to 6" of new snow. Southwest winds transported some of that load onto easterly slopes into the early evening. With few instruments in the northwest Flathead Range, there is some uncertainty about just how much snow accumulated west of Essex.

Be especially cautious below ridgelines and near crossloaded features at middle and upper elevations. Terrain features that stress the snowpack – convexities, unsupported slopes, and slopes steeper than about 30 degrees – are the most concerning. Opt for lower-angled, sheltered slopes for the safest and best conditions.

Weather and CURRENT CONDITIONS
weather summary

Several inches of new snow will continue to fall this morning before tappering off to snow showers this afternoon. High pressure builds into the region overnight with a warming trend through next week.

Two-Day Mountain Weather Forecast Produced in partnership with the Missoula NWS
For 5000 ft. to 7000 ft.
Wednesday Wednesday Night Thursday
Cloud Cover: Mostly Cloudy Partly Cloudy Mostly Cloudy
Temperatures: 25 to 31 deg. F. 13 to 18 deg. F. 24 to 31 deg. F.
Wind Direction: Northeast West Southwest
Wind Speed: 12mph gusting to24 around 9 mph 10mph gusting to 22
Snowfall: 1" to 3" in. 0" in. 0" in.
Snow Line: 2000' 1500' 1000'
Disclaimer

This forecast applies only to backcountry areas outside established ski area boundaries. The forecast describes general avalanche conditions and local variations always occur. This forecast expires at midnight on the posted day unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.