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GNFAC Avalanche Advisory for Mon Mar 8, 2010

Not Current Advisory

Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 8, at 7:30 a.m.  Gallatin County Search and Rescue, in cooperation with the Friends of the Avalanche Center, sponsors today's advisory.  This advisory does not apply to operating ski areas.

Mountain Weather: 

High pressure and spring like conditions continue to dominate the weather pattern in southwest Montana.  Temperatures have remained well above average with highs in the 40's F and lows in the 20's F and winds have remained light out of the west at 5-10 mph.   Currently, temperatures are in the upper twenties to low thirties and winds have picked up slightly out of the west at 10-15 mph.  As the day progresses we should start to see increasing clouds with continued warm temperatures reaching into the mid to upper 40's F.  Southwest Montana could see a slight change in weather starting tomorrow.

Snowpack and Avalanche Discussion: 

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

Where has winter gone?  At this point it seems like the lamb has been sheared and the lion has moved to the east coast.  With March typically being our snowiest, the lion needs to move back west in hurry.  As the warm weather slowly chips away at the snowpack, avalanche conditions have mellowed out.  This reduction of avalanche activity can be attributed to a few different factors. 

One: The weak layers in the snowpack have gained some strength.  Buried surface hoar 1-2 feet below the surface has slowly been compressed, reducing the sensitivity of this problematic layer.  Weak, near surface facets also found 1-2 feet below the surface have started to round and bond to the surrouding layers making them less likely to propagate a fracture.  And last but not least, the ever stubborn and persistent facets near the ground have actually started to bond and make friends with one another making full depth releases less likely.  Who would have ever thought? 

Second: The lack of snow and wind has not applied any additional stress to the existing snowpack.  This has allowed the pack time to adjust to any imbalances it may have been dealing with over the past few weeks creating an overall stronger snowpack.

Despite the fact weak layers within the snowpack are starting to show signs improvement, they have not gone away completely.  It is still possible to find weak snow 1-2 feet below the surface and also near the ground.  Each one of these weak layers is still capable of failing and producing an avalanche when exposed to the proper amount of stress.  Wet snow avalanches also need to be considered on all slopes that have high exposure to the sun.  With lingering instabilities and wet snow avalanches continuing to pose a threat, human triggered avalanches are possible and the avalanche danger is rated MODERATE.            

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. 

Avalanche Education & Events 

1. Bell Lake Yurt, Tobacco Root Mountains

Montana Backcountry Adventures - Level I Avalanche Course

Wednesday, March 10th to Friday, March 12th

For more info call 995-3880 or go to www.skimba.com

Audio: 
Audio for Mar 8, 2010