Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, March 20 at 7:30 a.m. A Montana Fish Wildlife & Parks Recreation Trails Grant sponsors today’s advisory. This advisory does not apply to operating ski areas.
At 5:02 a.m. we officially waved goodbye to winter and gave a welcome handshake to spring. Winter was a good guest this year: not too ornery and pretty fun.
Another inch of snow fell in the southern mountains before the skies cleared yesterday morning. By afternoon temperatures rose into the mid-20s, westerly winds decreased and sunny skies prevailed. Mountain temperatures are still near 20F with winds averaging 15-25 mph out of the southwest. Today will start cloudy, get sunny later this morning, then cloud over again. Mountain temperatures are expected to climb above freezing. Tonight a moist disturbance from the southwest will drop freezing levels and bring snow, favoring the southern mountains. By morning there should be 3-6 inches.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
From Saturday night to yesterday morning the mountains have gotten 6-12 inches of snow with strong winds. This snow fell onto a supportable melt-freeze ice crust on most aspects. Ice is a funny thing because we associate it with being slippery, yet that is not how it usually behaves once it’s buried. The recent snows have bonded well to the crust and we could not get it to break in our stability tests in the Bridger Range on Monday (snowpit). Even on higher, cooler, shaded slopes without the crust, our results were the same. Winds formed soft slabs near the ridgelines, but these have strengthened and are unlikely to be triggered. Skiers south of Bridger Bowl could not get anything to move, nor could the ski patrols around Big Sky.
The stability of the snowpack is very good. The exception would be on a few steep, rocky slopes with a thin snow cover comprised of weaker, sugary snow. These isolated areas are found in every mountain range in the advisory area and will be easy to spot and avoid.
For today, the avalanche danger is rated LOW on all slopes.
Wet Snow Avalanches (photo)
Today, above freezing temperatures will soften the snow surface. Pinwheels rolling downhill or sinking in past your boot tops in wet snow are signs the surface is wet enough to slide. If the sun beats down for any length of time I expect the wet snow avalanche danger will rise quickly to MODERATE.
Mark 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.