Mar 8, 2010 @ 12:00 am

March 8 Avalanche Advisory

Good morning, this is Dudley Improta with the West Central Montana Avalanche Center’s avalanche advisory for March 8, 2010. This is the last regular Monday advisory for the remainder of the season. Friday advisories will be posted, along with updates if warranted, until the end of March.

Current Avalanche Danger
On slopes above 5000 feet and steeper than 35 degrees there is a MODERATE avalanche hazard. On all other terrain in the advisory area the avalanche hazard is LOW.

Weather and Snowpack Analysis
Since Friday’s advisory the temperatures have been warm to say the least. The persistent surface slab we have been talking about for the past two weeks has gained strength but continues to react moderately to stability tests and can still be found above 6500′ on shaded, cold aspects and on West aspects as well. The sun- drenched South and East slopes pose a problem during the heat of the day. I have posted a photo of a wet slide at lower elevations in the Lolo Pass area at the end of our 2010 folder. This avalanche ran over 300 feet and was large enough to bury someone. This was on a sun-exposed southerly aspect.
Lolo Pass area wet slide 3/6/10
We received an e-mail with this youtube link that shows a slab avalanche triggered by dropping a cornice on 3/6/10. This avalanche on the North side of Morrell Mountain in the Seeley Lake area was sent in from the guys at Yurtski. This demonstrates the previously mentioned persistent slab on the colder aspects.
We are, however, expected to get cold weather and some snow. This could reduce the risk of wet warm slides and further weaken cold aspects.

Weather Forecast and Avalanche Outlook
A cold front is predicted to show up Monday afternoon. The higher elevations could see significant snow over the next couple of days. The Rattlesnakes, Southern Missions and Seeley Lake may see the most precipitation within the advisory area. I would pay close attention to higher elevation slopes that already have weak surface snow (W, NW, N, and NE) for the next few days. We had very strong surface temperature gradients on these aspects during the warm weather. This created surface layers of faceted snow. If we do get 10 to 15 cm of new snow the surface may be unstable immediately.
We definitely want the snow; pay attention to steep slopes on these aspects at elevation if it happens.

Steve will post the next advisory on March 12.

If you get out and see avalanche activity or want to send us quick snow observations, send us a note at [email protected] or call us at 406-530-9766 (530-9SNO).


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.