Avalanche Forecast published on November 29, 2014 @ 7:16 am
Issued by Erich Peitzsch - Flathead National Forest

Whitefish Range
Swan Range
Flathead Range and Glacier National Park

How to read the forecast

Dangerous snowpack conditions exist. 7-12 inches of new snow with strong winds deposited onto a weak snowpack in a very short period of time has likely created unstable conditions.  If you choose to ride or ski today, then avoid steep slopes and pay close attention to the terrain around you. Be conservative in your decision making and terrain selection.

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Above 6500 ft.

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5000-6500 ft.

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3500-5000 ft.
Forecast discussion

The snowpack has a strong distaste for rapid change. Thursday and Friday were relatively mild and warm with many mountain locations at or above freezing. This likely created a crust upon which this new snow falls. Then, temperatures plummeted with new snow and wind in a very short time span. The crust is now another bed surface for avalanches to slide on. But, let's not forget about that pesky weak snow (facets) near the ground that developed during the early November cold snap. While the recent mild weather may have helped to strengthen this layer a bit, it still exists and should be treated as suspect especially with a heavy, rapid load like this. This weak early season snowpack is a tough pill to swallow as everyone is powder starved, but the snowpack is weak. The strong winds with this storm likely created wind slabs as well. East-northeast winds may have deposited snow on slopes we are not accustomed to seeing as typical wind loaded slopes. 

Conservation decision making and terrain selection is hugely important if you choose to venture out today. Avoid steep slopes, areas with deposited snow, and stay out of runout zones. Allow the snowpack time to adjust, and remember that it may take a few days or more for this to occur. Carry your avalanche gear (beacon, shovel, and probe) with you. Look for obvious signs of instability like recent avalanche activity, cracking of the snowpack, and whumpfing (collapsing). Also, with a shallow early season snowpack any avalanche (even a small one) could take you for a nasty ride over rocks and stumps. Ask yourself if early season turns or riding is worth it before committing to any steep slope. 

We are currently in the field getting a handle on the snowpack. We need more data before we begin issuing hazard ratings and regular advisories. We intend to issue our first advisory December 6, and, until then, will provide updates as conditions warrant. If you are out in the backcountry please send us your observations by submitting them on the Observations page, emailing us at fac.admin@flatheadavalanche.org, or by calling 406.387.3835. 

recent observations

Our data are limited due to very few observations, but the amount of new snow accompanied by strong winds have likely created unstable conditions. I observed a moist, dense snow surface and a shallow snowpack the past two days near Big Mountain in the southern Whitefish Range and a weak snowpack in the Swan Range last Tuesday (video).

Remember that at this time there is no avalanche control and the slopes at ski areas have uncontrolled backcountry conditions. The terrain at ski areas can feel safe and familiar, but currently the snowpack there is just the same as the backcountry. It is important to carry your beacon, shovel, and probe when traveling in the backcountry at all times.

 

Weather and CURRENT CONDITIONS
weather summary

What a change in just 12 hours! A cold air mass accompanied by new snow and strong winds pushed out the previous mild weather. Conditions are downright nasty right now.  I enountered very unpleasant blizzard conditions just driving into the office this morning (then the power went out)!  Remote mountain weather stations across and adjacent to the advisory area report 7-12 inches of new snow with strong winds out of the east-northeast. Temperatures range from -20º to 2º F this morning. Snowfall should taper throughout the day with temperatures remaining below 0ºF in the mountains.

Today’s weather observations near 6000 feet in the region
0600 temperature: -20 to 2 deg. F.
Max. temperature in the last 24 hours: 39 deg. F.
Average wind direction during the last 24 hours: ENE
Average wind speed during the last 24 hours: 12-17 mph
Maximum wind gust in the last 24 hours: 51 mph
New snowfall in the last 24 hours: 7-12 inches
Total snow depth: 19-51 inches
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.