The avalanche danger above 5000 feet is MODERATE. In most locations the snow surface is saturated and it will be possible to trigger a wet snow avalanche on steep terrain. Also be aware that recent strong wind gusts have formed fresh wind slabs in the upper elevations. In isolated areas a cohesive slab exists over a layer of buried surface hoar. Evaluate snow and terrain carefully before comitting to a slope. Below 5000 feet the avalanche danger is LOW.
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Above 6500 ft.
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5000-6500 ft.
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3500-5000 ft.
Recent warm wet weather has saturated our snowpack surface. All elevations dipped below freezing last night, and this morning, which has "locked up" and temporarily alleviated this problem. However, low to mid elevations received a weak refreeze and the thin surface crust at these elevations should disappear quickly this morning. Upper elevations received their first solid refreeze in several days and will require sustained sun to create a loose wet problem. If you venture into the backcountry today you may be able to trigger loose, wet avalanches on steep slopes. Even though wet, loose avalanches are a manageable problem they can entrain a lot of snow and have severe consequences. They pile up quickly in narrow gullies and can run you through the trees.
A layer of buried surface hoar exists 6-14 inches below the surface in some areas. In recent observations, this layer fractured in most stability tests, but only propagated in isolated areas. This could change with the combination of recent warm temperatures, wind drifting, and the stress added by the additional load today. Buried surface hoar is tricky to manage due to the variability in distribution. It is important to dig into the snow, see where the layer is, and test the reactivity of this layer with stability tests before committing to a slope.
Recent warm weather kept snow levels this weekend high except for a brief period yesterday afternoon. Therefore, fresh windslabs will be confined to the upper elevations. Despite the wet heavy snow, upper elevation locations received winds strong enough to move this snow around in favored locations. In some areas slabs may have formed on a preserved layer of surface hoar making them more sensitive. Carefully assess all wind loaded terrain before commiting to an upper elevation wind loaded slope today.
Additional Concern: Recent strong winds, rain and heavy wet snow have added size and weight to existing cornices. Continued warm temperatures and winds adding additional weight could cause cornices to become unstable. As we approach spring and daily maximum temperatures rise above freezing, cornices will likely become more sensitive. Cornice failure can also be triggered by the weight of a skier or rider, and last week we found cornices that failed easily from the weight of a skier (observation). Cornices can also trigger slab avalanches on the slopes below making the consequences more severe. Give these large masses of overhanging snow a wide berth while traveling along ridges and limit your exposure time when traveling below them.
Saturday: Snow bikers were in the Red Meadow area in the northern Whitefish Range and observed natural loose, wet avalanche activity in the afternoon (photo). They also noted southwest winds cross-loading slopes and increasing the size of cornices in the area. We were on Skookoleel Ridge in the southern Whitefish Range. On slopes that were exposed to the sun on the previous day we found a supportable surface crust. On previously shaded aspects the unconsolidated snow was getting moist and roller balls formed in steeper terrain in the afternoon (observation). In isolated areas we found buried surface hoar about 14 inches from the surface (photo). Stability test results were variable due to variability in slab formation above. In one location where a soft windslab had formed, the surface hoar fractured and propagated across the column with hard force.
Friday: Skiers on Essex and Snowshed Mountains in the Flathead Range reported two weak interfaces in the upper-snowpack. They observed evidence of recent wind loading, and noted a thin crust forming on north facing slopes in the afternoon (observation). Skiers in the Apgar Range in Glacier National Park found a thin (9 inches), firm slab that fractured and propagated with hard force in extended column tests (observation).
Thursday: Skiers in the Marion Lake area of the Flathead Range reported a couple of recent and somewhat reactive graupel layers within the top foot of the snowpack (observation).
Wednesday: In Cascade Creek in the Flathead Range, we found stubborn wind slabs on wind loaded slopes, but still did not trust wind loaded terrain. We also found buried surface hoar 6-14 inches from the surface in more shaded areas sheltered from the wind (observation) that fractured but did not propagate in extended column tests. Lower elevation snowpack is dwindling rather quickly and has become more spring-like.
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
A warm wet system moved through our area yesterday morning producing snow levels in the neighborhood of 7000 feet! A cold front arrived in the afternoon but unfortunately the moisture tap was about played out by the time of its arrival. Valley floor and upper elevation stations reported .10 - .90 inches of water and 0-4 inches of snow. Maximum temperatures above 6000 feet ranged from 36 - 42° F with even the Snowslip (7020 feet) station in southern Glacier Park topping out at 39° F. Winds were light to moderate out of the southwest with occasional strong gusts. The Hornet weather station in the northern Whitefish Range reported 3 continuous hours of maximum gusts of 50 mph or greater. Currently, mountain temperatures range from 22°-31° F, winds are light with moderate gusts and we have partly clear skies. Today another system will move into our area later this afternoon/early evening. Maximum temperatures will reach the mid to upper 30's F with light winds and moderate gusts in the Flathead Range.
| 0600 temperature: | 22-31 deg. F. |
| Max. temperature in the last 24 hours: | 36-40 deg. F. |
| Average wind direction during the last 24 hours: | SW |
| Average wind speed during the last 24 hours: | 5-15 mph |
| Maximum wind gust in the last 24 hours: | 24-51 mph |
| New snowfall in the last 24 hours: | 0-4 inches |
| Total snow depth: | 74-100 inches |
| Monday | Monday Night | Tuesday | |
|---|---|---|---|
| Cloud Cover: | Partly sunny with light snow showers developing this afternoon. | Light snow showers. | Snow showers tapering. |
| Temperatures: | 35-47 deg. F. | 22-29 deg. F. | 32-44 deg. F. |
| Wind Direction: | S-SW | W-SW | SW |
| Wind Speed: | 5-6 | 8 gusts 20-23 | 10-14 gusts 25 |
| Snowfall: | 0 in. | 0-1 in. | 0-2 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.
