Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, February 21st at 7:00 a.m. Today’s advisory is sponsored by the Community Food Co-op and Cooke City Super 8/Bearclaw Bob’s. This advisory does not apply to operating ski areas.
In the last 24 hours the northern mountains received a trace to 1” of snow while the south got 10-18”. Winds have been blowing strong from the southwest with gusts of 50-78 mph yesterday afternoon and gusts of 40-60 mph this morning. Mountain temperatures are in the mid-20s under mostly cloudy skies. The storm will end this morning and skies will begin to clear this afternoon. Winds will remain strong out of the southwest and the southern mountains will pick up another 2-4” this morning.
A moist southwest flow has hammered the southern mountains. In the last 24 hours 1.3” of snow water equivalent (SWE) fell near West Yellowstone, Cooke City and Carrot Basin. This brings a 3-day storm total of 2.5” SWE (estimated to be 2’ of dense snow) to most areas. Besides snowfall, strong and gusty winds from the southwest will continue to load many slopes. New snow and wind are the one-two punch needed to make avalanches, and today there will be avalanches. Some slopes around West Yellowstone, and the southern Madison and Gallatin Ranges have a weak layer of facets and/or surface hoar buried 2-4’ deep which will easily avalanche from the weight of the storm snow (photo). Slopes without this layer will fare only slightly better as 2.5” of SWE with wind-loading will avalanche naturally. Slopes that avalanched earlier can break a second time which ice climbers discovered on Sunday, east of Cooke City (photo). For today, the avalanche danger is rated HIGH on all wind-loaded slopes and CONSIDERABLE on all others. Stay clear of avalanche terrain today since most avalanches occur during and immediately after a storm.
Bridger Range Northern Madison Range
In the last 24 hours the northern mountains have gotten blasted by the winds. The 5-6” that fell on Sunday in the Bridger Range blew into drifts that have become harder to trigger. Around Big Sky a layer of weak snow (facets) 1.5-2’ deep is breaking clean in stability tests. Although we have not seen avalanche activity on this layer, we do not trust it. There’s nothing like seeing a column snap off with a few hand taps to snap me to attention. Since avalanches are still possible to trigger the danger is rated MODERATE on all slopes.
Northern Gallatin RangeIn the northern Gallatin Range stability is good and triggering avalanches is unlikely. Winds are strong, but there’s a lack of snow to blow around. The hazards today are related to knee-twisting breakable crusts and cornices peeling away underfoot. For today, the avalanche danger is rated LOW on all slopes.
I will issue the next advisory tomorrow morning by 7:30 a.m.
Less People, More Fatalities, a new article by Doug Chabot on avalanche fatality trends in Montana.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.
Beacon Training Park at Beall: Open and free to the public for avalanche beacon practice seven days a week from 9 a.m. to 8 p.m., southeast corner of Beall Park in Bozeman.
COOKE CITY
Weekly rescue training and snowpack update, 6:30-7:30 p.m., Cooke City Super 8 on Friday, Lulu Pass Road for field location Saturday (Look for the yellow sign).
Bozeman
March 1, 1-hr Avalanche Awareness, 6-7p.m., REI Bozeman.
March 4, Pinhead Classic, Proceeds to benefit Friends of GNFAC. More info here.