Good morning. This is Mark Staples with the Gallatin National Forest Avalanche Advisory issued on Thursday, March 19, at 7:30 a.m. Cooke City Motorsports and Yamaha in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
Yesterday morning a little more precipitation fell in most areas as rain at elevations below 7000 ft and ½ to 1 inches of snow at elevations above 9000 ft (.1-.3 inches of SWE). In between I’m not sure if it rained or snowed. More importantly temperatures dropped and skies cleared overnight with temperatures this morning in the high teens to low 20s F. Winds this morning were blowing westerly at 10-20 mph. Today will have strong sunshine and rapidly rising temperatures which should reach the 40s F but feel much warmer. Winds should blow 5-15 mph from the WSW.
Bridger Range Madison Range Gallatin Range
Lionhead Area near West Yellowstone Cooke City
Good news: The snowpack experienced a good freeze last night with cold, clear skies and cool temperatures this morning.
Bad news: The snowpack only refroze near the surface and probably remains wet underneath. Strong sunshine today will restart the melting process and more wet avalanches should occur.
Yesterday a rider at Lionhead near West Yellowstone spotted a large wet slide triggered early this week (photo). The Bridger Bowl Ski Patrol triggered a large wet slide that put a sizable debris pile in South Bowl. This avalanche took most of the snowpack in the starting zone then entrained the new snow on top of a soft crust as it ran further downhill. At elevations above 9000 feet, the Big Sky Ski Patrol easily triggered dry snow wind slabs about 1 foot thick on all aspects. They were surprised with the sensitivity of these wind slabs and how far they propagated. Nearby in Beehive Basin, a skier saw a few wet slides on south facing slopes and described the snowpack as “total wet garbage.”
I don’t expect avalanches early this morning because the snowpack got pretty wet yesterday and froze overnight. There should be a short window of decent riding conditions as temperatures rise and the snowpack warms. Then, riding conditions and stability should deteriorate quickly. On all aspects below 9000 feet except due north, the snowpack will warm quickly and the avalanche danger will be CONSIDERABLE. At higher elevations or shaded north aspects, the avalanche danger will be MODERATE where the snowpack won’t heat up as fast but some fresh wind slabs may be found.
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.