Avalanche Advisory March 28, 2014

There is MODERATE avalanche danger in the West Central Montana backcountry above 5000 feet, on slopes steeper than 35 degrees. Avalanches involving new snow or fresh wind slabs are possible on steep (>35 degrees) slopes. Rain on the snow may produce avalanches on melt-freeze crusts in the snowpack. Warmer temperatures can make cornice failure more likely.

In the last 24 hours the southern Missions, southern Swans and central Bitterroot picked up more snow than the general advisory area. Due to the increased load, the snow will be more sensitive in these locales.

Good Morning, this is Dudley Improta with the West Central Montana avalanche advisory for March 28, 2014. This danger rating does not apply to operating ski areas and expires at midnight tonight (March 28). This is our last regularly scheduled advisory for the season.

We will continue to post public observations that are sent in.

Weather and Snowpack

This morning westerly mountain winds are blowing around 13  mph and gusting into the 20’s . Mountain temperatures are in the low to upper 20 (F) degree range. The area picked up snow yesterday and it is snowing this morning. Generally there are 5 to 6 inches of new snow; but the North Fork Jocko Snotel is showing 8 inches and Twin Lakes Snotel is showing 11 inches. The snow in the southern Missions and Swans, as well as the central Bitterroots will be more sensitinve due to the increased load.

Travis and I were in the Rattlesnakes yesterday; Tim and Dave checked out the snow near Lolo Pass. We had the same avalanche concerns:

1. New, loose snow was sluffing easily on steep slopes. The new snow from Wednesday night and Friday did not bond well to the old surface layer. There is about a half a foot of snow that will slide. Get enough of it going on a big, steep slope and it could be an issue. The wind will have increased the amount of snow on leeward slopes; creating wind slabs above 7000 feet.
2. The multiple crusts I talked about Tuesday are still present in the snowpack (Rattlesnake profile) (Lolo Pass profile). They are not producing energetic failures in tests; but they could produce avalanches by allowing  horizontal movement of water in the snowpack if (when) it rains.
3. Cornices are large this year. Avoid them during warm weather.

David Fox and Geoff Fast were out near Lost Trail Pass. Their main concern was also the new snow, but near 8000 feet wind slab formation was number one on the list, with loose snow avalanches a secondary worry.  They also noted the chance of deeper layers failing (Lost Trail profile)  and cornice failure.

Weather Forecast and Avalanche Outlook

Tonight and Saturday a wet Pacific system is expected to move into the Bitterroot Mountains. The storm could produce up to an inch of water equivalent in the Bitterroots.  Other mountains in West Central Montana should expect at least a half an inch of water equivalent.

Heavy, wet snow will increase the avalanche danger.

I hate to leave with the previous sentence on our last regular advisory – so I won’t. Many of you will be in the mountains this spring, as you should; we have a ton of snow out there. Generally, the snow tends to stabilize as spring progresses. But, late-season avalanches are not that rare; so keep the radar up. Heavy snowfalls, rain, the heat of the day and cornices are some of the things that should get your attention when riding or skiing the steeps this spring.

missoulaavalanche.org (West Central MT Avalanche Foundation)

The relationship between the West Central Montana Avalanche Center and missoulaavalanche.org can sometimes be confusing. Missoulaavlanche.org is a 501(3)(c) that supports the Center through a cost-share agreement with Lolo National Forest.

Although the Forest Service is responsible for the avalanche advisories; missoulaavlanche.org provides all operating funds, including salaries for the forecasters (avalanche specialists) and educators. Funds are raised primarily through the efforts of the folks on the missoulaavalanche.org Board of Directors. They are Mark Waller (Chair), Steve Porcella, Spencer Bradford, Ross Peterson, Russ Read, Mike Birnbaum, Justin Metcalf, Zachary Millar, Mark Fricke and Katy-Robin Garton.

Without their hard work it would be difficult, if not impossible, for the Center or the advisories to exist. The community is fortunate to have these folks volunteering their time.

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

This is our last scheduled advisory for the 2013/2014 season.

Ski and ride safe; enjoy the spring snow.