GNFAC Avalanche Forecast for Mon Apr 6, 2015

Not the Current Forecast

Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, April 6, at 7:30 a.m. Cooke City Bear Claw/Super 8 and JA Gear sponsor today’s advisory. This advisory does not apply to operating ski areas.

Mountain Weather

Easter Sunday delivered a nice shot of snow to the mountains of southwest Montana. Over the past 24 hours the Bridger Range received 5-6 inches of new snow. The rest of the advisory area picked up 3-4 inches. At 4 a.m. it has stopped snowing and temperatures are in the upper teens to mid-20s F under cloudy skies. Winds are fairly light blowing 5-15 mph out of the W-SW with gusts around Big Sky blowing 20 mph. Today, temperatures will warm into the upper 20s to mid-30s F under cloudy skies and winds will continue to blow 10-20 mph out of the W-SW. A moist southwest flow will keep conditions unsettled and the mountains south of Bozeman could see 1-3 inches of new snow during the day. The Bridger Range could see a trace to one inch. Snow tapers off this evening and Tuesday looks like a nice day.

Snowpack and Avalanche Discussion

Bridger Range   Gallatin Range   Madison Range  

Lionhead area near West Yellowstone   Cooke City

After a warm and dry winter 4-6 inches of new snow seems like a lot. Although not epic powder, it is enough to improve overall skiing and riding conditions as well as elevate the avalanche danger. The new snow fell on a variety of snow surfaces ranging from soft snow on north facing slopes to frozen chunder on southerly aspects. I do anticipate the new snow to bond well to the old snow surface, but there are a few avalanche problems to watch out for.

The primary avalanche problem today will be wind slabs. Wind deposited snow will most likely be encountered on upper elevation slopes loaded by west-southwest winds. Fresh wind slabs won’t be exceptionally large, but they will be sitting over a firm bed surface making them susceptible to human triggers. The good thing about wind slabs is they are fairly easy to recognize and avoid.

A secondary avalanche problem will be loose snow avalanches or sluffs. In steep terrain, sluffs could generate a fair amount of speed and volume once initiated. It’s unlikely that sluffs will occur naturally, so pay attention the snow moving under your skis or sled and manage this problem accordingly. Loose snow avalanches are most problematic in steep, high consequence terrain where even a small ride can have a poor outcome.

Today, human triggered avalanches are possible on wind loaded slopes and slopes steeper than 35 degrees which have a MODERATE avalanche danger. All other slopes have a LOW avalanche danger.   

Doug will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.

RECALL OF ORTOVOX S1+ AVALANCHE TRANSCEIVERS

All necessary information about the recall can be found at: www.ortovox.com/recall-s1plus.

The last advisory of the season will be Sunday, April 12.

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