GNFAC Avalanche Advisory for Mon Mar 29, 2010

Not the Current Forecast

Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 29, at 7:30 a.m.  Pinhead Classic Telemark Festival, in cooperation with the Friends of the Avalanche Center, sponsors today's advisory.  This advisory does not apply to operating ski areas.

Mountain Weather

Since yesterday afternoon winds have increased and clouds have moved into our area ahead of a strong pacific storm system.  This morning, winds have been blowing consistently at 20-40 mph out of the W-SW, with gusts reaching 60 mph in the Bridger Range.  Temperatures are on the mild side with lows in the upper twenties to mid thirties F.  Today, winds will remain strong out of the W-SW and mountain temperatures will rise into the mid to upper forties F.  Precipitation will move into our area starting later tonight and we should see 3-5 inches of snow above 7,000 ft by tomorrow morning.

Snowpack and Avalanche Discussion

The Bridger Range, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:

Springtime in Montana is known for its unpredictable weather that to keeps us guessing.  This spring has been no exception.  March entered more like a lamb than a lion, but is roaring on its way out.  Snow producing systems keep lining up, and after a couple of fair weather days, yet another is heading down the barrel towards southwest Montana.

Luckily, the past two days have allowed the snowpack time to adjust to the load of the previous two storms, helping quiet avalanche activity throughout our forecast area. However, this does not mean that the avalanche hazard has vanished.  A thin layer of faceted crystals that formed during the first half of March now sits 1-2 feet below the surface and can be found throughout our advisory area, extending from Cooke City to the northern Bridgers (video). 

Although this layer varies in sensitivity, it has consistently demonstrated its ability to propagate a fracture and produce both natural and human triggered avalanches, especially on recently wind loaded slopes.  A skier found this out on Saturday when he triggered a small wind loaded slope north of Bridger Bowl (photo).  Yesterday, another skier triggered a small wind loaded slope outside of Cooke City (photo).  Although these slides were relatively small, they are a good indication that instabilities are still lingering in the snowpack.   With more snow and wind on the way, these buried weak layers will likely become an increasing problem.

Today, with buried weak layers present in the snowpack and strong winds overnight, human triggered avalanches are probable on all wind loaded slopes steeper than 35 degrees where the avalanche danger is rated CONSIDERABLE.   All other slopes have a MODERATE avalanche danger.

YouTube: Saddle Peak Avalanche Q&A

The Saddle Peak Avalanche Q&A held March 4th at the Bozeman Public Library is now online thanks to the Randy and Kristin Wimberg.  The entire 75 minute session can be viewed in two parts. Find it on our Videos Page or here: Part 1, Part 2.

Doug will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry let us know what you find.  You can reach us at 587-6984 or email us at mtavalanche@gmail.com.

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