Mar 4, 2014 @ 6:34 am

Avalanche Advisory March 4, 2014

The avalanche danger is CONSIDERABLE in the West Central Montana backcountry on slopes 30 degrees and steeper. New, heavy, wet, snow has loaded steep slopes in the area. We aren’t on an area-wide avalanche warning, but make no mistake; there is some very touchy snow out there. Any rain on the snow and all bets are off; the rain’s immediate effect will make the snow less stable.

Missoula Foothills Special Statement – In the foothills surrounding Missoula there is HIGH avalanche danger in basins and gullies steeper than 30 degrees. The heightened avalanche danger in the Missoula foothills is due to rain on unstable snow in the basins and gullies. An investigaton of the crown of the Mt. Jumbo avalanche on Sunday revealed unstable results with snow tests (Mt. Jumbo Crown profile) and collapsing of wind-loaded areas.

Please refer to the City of Missoula website for updates from the Mayor’s Office as well as the City Police and Fire Departments.

Good Morning, this is Dudley Improta with the West Central Montana avalanche advisory for March 4, 2014. This danger rating does not apply to operating ski areas and expires at midnight tonight (March 4).

We are saddened to hear of the passing of one of the people caught in the avalanche on Mt. Jumbo in Missoula on February 28. Our thoughts and condolences go out to the family and friends.

Weather and Snowpack Analysis

Westerly winds are blowing in the 20mph range at higher elevations this morning. Mountain temperatures are warm, ranging in the high twenties to low thirties. The area picked up several inches of snow last night; 5 inches in the southern Bitterroot, 4 inches in the Rattlesnake, 7 inches at Hoodoo Pass. This new snow is likely heavy and wet.  We are currently under a winter weather advisory.

Travis and I traveled in the Rattlesnakes yesterday and found a wildly variable snowpack. The northerly aspects appeared fairly stable (Rattlesnakes pit profile) while the south sides are loaded and reactive (Rattlesnakes video). Northerly winds loaded the south slopes in the Rattlesnakes and the new, relatively heavier, snow is sitting on a crust and colder snow. On March 2nd the Snowbowl Patrol, using explosives, triggered slabs, up to 20 inches in depth in southwest couloirs.

Tim and Dave also found  heavy, wet snow sitting on colder snow near Lolo Pass yesterday. (Lolo Pass pit profile). All the steep road cuts near Lolo Pass were naturally sliding.

I got a call from the Yurtski guides (Southern Swans) March 2. Although their pits were showing fairly stable results; they were remaining cautious of wind-loaded areas. The winds there, as we found in the Rattlesnake, have loaded slopes that are not the usual suspects.

Parts of I-90 near St. Regis were closed yesterday afternoon due to rain-induced wet slides.

Weather Forecast and Avalanche Outlook

A warming pattern should remain through the week. Perhaps some significant snow will develop today over the mountains with off and on showers into Friday. The snow predicted will be heavy and wet; with possible rain up to 6000 feet. The warmer, heavier snow may settle quickly; but the immediate effect of a heavy load, or rain, will destabilize the snowpack.

If you would like to send us snow observations; you can use our public observations form on the internet or send us a quick e-mail at  [email protected] .

Ski and ride safe.

I will issue the next advisory on Friday, March 7.


This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but the information can help you make a more informed decision regarding travel in avalanche terrain for the next few days.

Our advisory area includes National Forest System lands in the Bitterroot Mountains from Lost Trail Pass north to Granite Pass, the Rattlesnake Mountains north of Missoula and the Southern Swan and Mission Mountains near Seeley Lake, MT. Avalanche information for the Lookout Pass/St. Regis Basin area is available from the Idaho Panhandle Avalanche Center.