Archived Advisory for Tue Jan 8 2008

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TUESDAY, JANUARY 8

Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, January 8th, at 7:30 a.m. Jeff King at Edward Jones Investments, in cooperation with the Friends of the Avalanche Center, sponsor today’s advisory. This advisory does not apply to operating ski areas.

MOUNTAIN WEATHER

Overnight 1-2 inches of new snow fell with winds blowing west to southwest at 10-20 mph. Temperatures at 5 a.m. are in the single digits and are expected to rise into the teens under mostly cloudy skies. Winds will pick up from the southwest and another storm approaches tonight. By tomorrow morning we should have 1-2 inches of new snow in the north and 2-4 inches down south with showers continuing through Wednesday.

SNOWPACK AND AVALANCHE DISCUSSION

The Bridger Range:

The snowpack in the Bridger Range has become relatively stable in the last week. Snowpits in the area, including reports from the Bridger Ski Patrol, all indicate well bonded layers. Wind-loaded slopes near the ridgetops, as well as those cross-loaded from southerly winds this weekend, are our only avalanche concern. Thus, for today, the avalanche danger on wind-loaded slopes steeper than 35 degrees is MODERATE while all other slopes have a LOW danger.

The northern Gallatin Range and northern Madison Range:

The northern Gallatin and northern Madison Ranges continue to have unstable snow on many slopes. Over the weekend folks triggered slides in Beehive Basin and I found unstable conditions on Yellow Mountain which had recently avalanched. Snow and strong winds in the last 48 hours are preventing the danger level from dropping. If you tour around you’ll find an entire menu of conditions: thin snow cover that collapses and cracks; mid-pack faceted grains that are fracturing clean; wind slabs prone to avalanche; and areas where the snow is especially deep, stable and holding great powder. Since the conditions are highly variable you’ll need to be diligent in assessing the snow in order to travel safely. Today the avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees. Slopes that are less steep have a MODERATE danger.

A snowmobiler triggered slide on Saturday on a small hill in the Bangtail Mountains, located immediately east of the Bridger Range, broke 3 feet deep and a few hundred feet wide. The snowpack here looks similar to other slopes in our northern mountains: a thick layer of faceted snow capped with a hard wind slab. The pictures say it all. Check them out at: http://www.mtavalanche.com/photos/photos.php

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

The southern mountains, including the Lionhead area and Cooke City region, have gotten close to 2 feet of snow since Friday night. Scott and I rode around Lionhead on Sunday digging snowpits, looking for avalanches and choking on powder. The winds hammered portions of the range, but even high elevation, leeward slopes were not naturally avalanching. Human triggered slides, however, would be another story, especially on wind-loaded slopes. At Lionhead we were finding weak snow, now buried 18-24 inches deep, fracturing clean in our stability tests. In the Cooke City area, since 2 riders were caught and buried in slides 6 days ago, 1 ˝ feet of additional snow fell with strong winds. In the southern mountains your safety will depend on your ability to differentiate between slopes that have a wind-load and those that do not. For today, the avalanche danger is CONSIDERABLE on wind-loaded terrain and MODERATE on all other slopes. Remember, a Considerable danger means that you will probably trigger a slide.

AVALANCHE EDUCATION

Tomorrow night at 7 p.m. in Livingston, Jay Pape will present a free 1-hour Avalanche Awareness Class at the Lincoln School. This annual event is sponsored by Timber Trails.

I will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry give us a call or email with your observations. You can reach us at 587-6984 or email us at mtavalanche@gmail.com .