The avalanche danger is MODERATE. Strong winds and a bit of snow created thin, fresh wind slabs at upper elevations. Carefully evaluate wind loaded terrain before committing to a slope. Warm temperatures are expected again today. Watch for prolonged periods of sunshine to break down the surface crust and increase loose, wet avalanche danger. Additionally, there is some uncertainty in the distribution of a layer of buried surface hoar so it is important to perform site specific snowpack evaluation.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Strong winds drifted the new snow and created another round of thin, windslabs. With the recent warm temperatures and high snow levels these slabs will be thin until you climb into the upper elevations. Remember that even small avalanches can do a lot of damage in consequential terrain. Look for smooth, rounded features on the snow surface along leeward ridgelines. Carefully evaluate wind-loaded terrain before committing to a slope.
Temperatures cooled last night and refroze the surface snow. Today, pay attention to warming temperatures and the potential for periods of sun exposure that will break down that crust and weaken the snow surface. Early signs of instability are pin wheels/roller balls forming on steep slopes indicating that it is time to move to more shaded terrain.
There is some uncertainty in the distribution of a layer of buried surface hoar that exists 1.5-2 feet deep in the snowpack. In all of our recent observations in the Whitefish Range we have found this layer and it has proven reactive in stability tests (video). We went on the hunt for it in the Swan Range yesterday and did not find it. We have not received any other recent observations from this area so I am not ready to write it off. We have also found this layer in the Flathead Range, but it was less reactive in stability tests. The Bottom line is that this layer exists across the advisory area and it is important to dig into the snow and look for it before skiing or riding a slope. In areas where you find this weak snow it would be wise to choose conservative terrain.
Additional Concerns: Also, as we approach spring and daily maximum temperatures rise above freezing on a more regular basis, cornices will likely become more sensitive and glide cracks could begin to fail. Cornices can trigger slab avalanches on the slopes below making the consequences more severe. Give cornices a wide berth while traveling along ridges and limit your exposure time when traveling below them.
Avalanche Danger Scale: The National Avalanche Center developed a great video for helping backcountry users visually understand the avalanche danger scale (video).
We are saddened to hear about a fellow avalanche professional being killed in an avalanche on March 8 in the Wallowa Mountains in Oregon. Our thoughts are with the family and friends of Kip Rand and those at the Wallowa Avalanche Center (info).
Saturday: Mark and I rode up to Hash Mountain in the Swan Range. On the ride through the Lost Johnny drainage we observed 2 small, recent slab avalanches (observation). The rain transitioned to wet, heavy snow at about 6000 feet. We found 3-5 cm of new snow on top of the most recent crust and noted lots of roller ball activity in the new snow (observation). Guy was on Paola Ridge in the Flathead Range yesterday. He found small, decomposing surface hoar buried 14 inches from the surface. This layer fractured with easy force in compression tests (observation).
Thursday: Erich and I traveled along a safe ridge outside the ski area boundary yesterday and remotely triggered a small storm slab avalanche from the ridge (observation 1) and observed widespread shooting cracks and a collapse (observation 2). We also found buried surface hoar 1.5 to 2 feet from the surface to fracture and propagate in our stability test with moderate force (video). Whitefish Mountain Resort Ski Patrol also reported very reactive storm and wind slabs during their avalanche mitigation work Thursday morning (observation).
Wednesday: Erich traveled to Red Meadow Peak in the northern Whitefish Range where we found up to 5 inches of low density snow sitting atop a firm rain crust all the way to 7500 feet. We also found buried surface hoar up to 2 feet from the surface that fractured and propagated in stability tests (observation, video). We noted wet, loose avalanche debris from the weekend, but no new avalanche activity.
Monday: Mark visited Rescue Creek in the Flathead Range and found evidence of a wet loose avalanche cycle from the weekends warm rainy weather. We also noted 2 glide cracks that had formed and a surface rain crust at all elevations (observation).
Visit our Observations page and our You Tube channel for more observations from the entire season.
Thanks to everyone for submitting observations. They are extremely useful and could help save lives.
HOW TO SUBMIT OBSERVATIONS:
Email: [email protected]
Call and leave a message: 406.387.3821
You can also submit quick observations via text: 406.241.4571 (FAC mobile)
OR
Submit Snowpack Observations: http://www.flatheadavalanche.org/node/add/snowobs
Submit Avalanche Observations: http://www.flatheadavalanche.org/node/add/avyobs
Overnight, the rain showers turned to snow with a passing cold front. We picked up 1-3 inches of new snow in the past 24 hours. Winds were out of the west-southwest at 10-20 mph with maximum gusts ranging from 28-57 mph. Currently, mountain temperatures range from 20º-27º F, and winds are out of the west-southwest at 7-24 mph* with gusts from 13-48 mph. Today we could see a few lingering showers before another wave of precipitation moves into the area tonight. Temperatures should rise to the mid-upper 30s, and winds will move out of the southwest at 10-20 mph.
*Note - several of our wind sensors stopped reporting late last night.
| 0600 temperature: | 20-27 deg. F. |
| Max. temperature in the last 24 hours: | 33-39 deg. F. |
| Average wind direction during the last 24 hours: | WSW |
| Average wind speed during the last 24 hours: | 10-20 mph |
| Maximum wind gust in the last 24 hours: | 28-57 mph |
| New snowfall in the last 24 hours: | 1-4 inches |
| Total snow depth: | 75-105 inches |
| Sunday | Sunday Night | Monday | |
|---|---|---|---|
| Cloud Cover: | Lingering showers. | Snow showers. | Snow showers. |
| Temperatures: | 32-46 deg. F. | 20-29 deg. F. | 28-40 deg. F. |
| Wind Direction: | SW | S-SW | SW |
| Wind Speed: | 10-15 gusts 24-32 | 18-20 gusts 37-41 | 21-24 gusts 33-41 |
| Snowfall: | 0-1 in. | 4-11 in. | 4-11 in. |
| Snow Line: |
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.
