THIS AVALANCHE ADVISORY EXPIRED ON April 5, 2017 @ 12:00 am
Avalanche Advisory published on April 4, 2017 @ 7:00 am
Issued by Adam Clark - Flathead Avalanche Center

Whitefish Range
Swan Range
Flathead Range and southern Glacier National Park

How to read the advisory

2. Moderate

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Above 6000 ft.

2. Moderate

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5000-6000 ft.

2. Moderate

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3500-5000 ft.

Today we can expect clearing skies and above-freezing temperatures by this afternoon. The avalanche danger will begin at LOW but then rise to MODERATE at all elevations as the day progresses. Sunshine and warm temperatures will weaken the surface snow, making it possible to trigger a loose wet avalanche. Pay attention to changing conditions and move to more shaded terrain if slopes facing the sun start to become unstable.

 

  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
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    Certain
    Very Likely
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Yesterday we picked up 2-4 inches of new snow. Today we can expect above-freezing temperatures and partly to mostly sunny skies which will heat the surface snow and increase the avalanche danger throughout the day. Watch for loose wet avalanches initiating on steep slopes near rocks and trees. East facing slopes will be the first to warm up and potentially become unstable, followed by the southern aspects, then the west-facing slopes by the afternoon. Pay attention to how the surface snow is changing today. Snow sticking to your skis/skins and snowmobiles are signs that the snow surface is starting to become unstable. If you start seeing rollerballs and/or natural wet loose avalanche activity, move to more shaded terrain.

Avalanche Problem 2: Cornice
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Massive cornices exist along many of the ridgelines across the advisory area. Warming temperatures and full sunshine will weaken these features and it is best to give them a wide berth. Be aware that cornices can break farther back on the windward side of the ridge than you might expect. Also keep in mind that falling cornices can trigger avalanches on the slopes beneath them. Avoid travelling on slopes underneath cornices today.

advisory discussion

Winds over the past 24 hours have been light and variable. Plus, with warm daytime temperatures and heavier surface snow, the amount of blowing snow has been minimal. Still, I suspect there may be some reactive wind slabs lurking up in the alpine terrain, especially on the more shaded aspects. Look for signs of wind drifted snow such as rounded pillows on leeward slopes if you're travelling above 6000 feet elevation today. Carefully evaluate any terrain where you find a cohesive slab and avoid slopes where you see the tell-tale signs of instability such as shooting cracks or recent avalanche activity.

Glide cracks have been opening up in many locations. Glide avalanches are notoriously unpredictable and it is best to avoid travelling on or beneath slopes where glide cracks are present. 

The last daily avalanche advisory of the season will be Sunday, April 9.

recent observations

Monday: Skiers on Elk Mountain in southern Glacier Park found about 4 inches of new snow on top of a supportable crust at 7000 feet and noted that wind-loading was minimal. They conducted an extended colulmn test in a snowpit at 6700 feet on a WSW aspect and did not get full propagation on any layer.

Sunday: FAC staff visited Skiumah Creek, in the Flathead Range where they noted old, large and impressive wet avalanche debris piles. The snow surface at low and mid elevations was moist and unsupportable on skis throughout the day. New snow that fell during the tour was being transported at all elevations by strong wind gusts.  

See below for all observations this season.

CURRENT CONDITIONS Today’s weather observations near 6000 feet in the region
0600 temperature: 16 to 26 deg. F.
Max. temperature in the last 24 hours: 26 to 39 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 1-9 mph
Maximum wind gust in the last 24 hours: 3-19 mph
New snowfall in the last 24 hours: 2-4 inches
Total snow depth: 86-128 inches
weather

Yesterday we picked up 2-4 inches of new snow as a quick moving system passed over our area. As of 6:00 am this morning, mountain temperatures range from 16 to 26º F. Winds are 1-10 mph gusting to 11 mph out of the south to southwest. Today expect a nice spring day with clearing skies and dry, sunny weather. Temperatures may climb into the mid 40s °F below 5000 feet elevation and into the mid 30s °F above this. Winds should be light, blowing mostly from the southwest.

Two-Day Mountain Weather Forecast Produced in partnership with the Missoula NWS
For 3000 ft. to 5000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Mostly sunny, warming temperatures Partly cloudy Warming but with increasing clouds
Temperatures: 32 to 46 deg. F. 17 to 27 deg. F. 37 to 51 deg. F.
Wind direction: south-southwest southwest south-southwest
Wind speed: 4-5 mph 5-6 with gusts to 17 mph 7-10 with gusts to 21 mph
Expected snowfall: 0 in. 0 in. 0 in.
For 5000 ft. to 7000 ft.
  Tuesday Tuesday Night Wednesday
Weather: Mostly sunny, warming temperatures Partly cloudy Warming but with increasing clouds
Temperatures: 27 to 37 deg. F. 16 to 25 deg. F. 35 to 44 deg. F.
Wind direction: southwest southwest southwest
Wind speed: 5-7 mph 8-10 with gusts to 28 mph 10-15 with gusts to 28 mph
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

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