Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, April 7, at 7:30 a.m. Soda Butte Lodge in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
Since yesterday morning snow squalls dropped 7 inches in the Bridger Range, 4-6 inches in the northern Madison and northern Gallatin Ranges and 1-2 inches further south to West Yellowstone and Cooke City. The storm has ended and at 5 a.m. temperatures are in the low teens under clearing skies. Gusts of 40 mph blew out of the W-SW early last night and have now calmed to 10 mph. Today will be mostly sunny but tonight clouds will build from a southwest flow and drop 1-2 inches around Cooke City.
Bridger Range Gallatin Range Madison Range Lionhead area near West Yellowstone Cooke City
The last 72 hours have been fruitful. About 13 inches (over 1 inch of SWE) has fallen in the Bridger Range and Big Sky area, with upwards of 10 inches reported outside Cooke City. Winds are currently calm, but have gusted up to 40 mph at different times over the last three days creating wind slabs. I was in Cooke City on Sunday and found that the new snow was bonding to the firm ice crust, but winds were easily building soft slabs that avalanched (photo). Yesterday a skier triggered one of these outside Cooke City which broke 4-10 inches deep, 40 feet wide and ran about 1,000 feet vertical (photo). Triggering it was a surprise and the party called it a “slap on the wrist” because it was an obvious oversight in serious, unforgiving terrain. After weeks of stable conditions it’s easy to get complacent. Close calls are welcome because they snap us to attention, even by reading about them.
Eric toured into Beehive and Bear Basins yesterday and also found the new snow bonding to the ice crust, but was wary about wind-loaded slopes (video, photo). Nearby the Big Sky Ski Patrol were able to get these wind-loads to release with ski cuts so his caution was justified. Avalanches won’t be deeper than the new snow or very wide, but they could run long distances given the hard underlying crust. For today, it will still be possible to trigger avalanches on wind-loaded slopes and these have a MODERATE danger. Slopes untouched by the wind will have creamy, generally stable snow and a LOW avalanche danger.
WET SNOW AVALANCHE DANGER
Slopes getting sun will warm quickly. Pinwheels rolling downhill are signs that the surface snow is wet and unstable. Loose, wet avalanches are possible today and the danger will rise to MODERATE as by late morning.
I 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.
The last advisory of the season will be this Sunday, so if history is any guide expect an epic dump on Monday. Just sayin’…