Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 26 at 7:30 a.m. Hans Saari Memorial Fund, in partnership with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
This morning mountain temperatures are in the mid 30s to low 40s with the exception of Cooke City which is recording a cool 31 degrees F. Skies are clear and winds are blowing 15-25 mph out of the SSW with gusts in Hyalite and Big Sky reaching over 40 mph. Today, temperatures will only warm a few degrees and skies will become mostly cloudy by early afternoon as a cold front approaches from the west. Winds will continue to blow 15-30 mph from the WSW with gusts reaching close to 50 as the front approaches. Precipitation in the form of valley rain and mountain snow will move over the area by this evening. 2-4 inches of snow will likely fall above 7000 feet by tomorrow morning.
WET SNOW AVALANCHE DANGER
The lack of freezing temperatures overnight will make wet snow avalanches a concern. Sun exposed slopes will be the most prone to wet snow instability. Roller balls, point releases and soft/wet snow deeper than a boot top are obvious signs the snow surface is becoming unstable. Today, the wet snow danger will start out LOW but could rise to CONSIDERABLE by this afternoon.
The Bridger Range:
Yesterday, no new avalanche activity was reported in the Bridger Range. This is surprising considering temperatures were in the 50s for much of the afternoon. Despite the absence of avalanches, the snowpack resembled a slurpee melting in the sun, providing additional free water to an already soggy pack. The avalanches that occurred this past Thursday and Friday are prime examples of what a wet and weak snowpack are capable of (photo, photo, video)
Today, the most likely place to start an avalanche will be steep, rocky terrain where underlying facets have the strength of a wet paper bag. Although the snowpack will likely revert back to its old crusty self as cloudy conditions prevail and cooler temperatures move into the region, this crust can be deceiving. The surface snow may be firm while the underlying layers of the pack remain warm, wet and weak.
Without a freeze last night, all slopes remain suspect. For this reason the avalanche danger is rated CONSIDERABLE.
The Gallatin Range, Madison Range, the Lionhead area near West Yellowstone and the mountains around Cooke City:
Yesterday, my partner and I toured into Beehive Basin and found a thick, supportable crust on most slopes. Warm temperatures and strong solar input broke this crust down by early afternoon, producing widespread wet loose avalanche activity. The Big Sky Ski Patrol noted a significant wet loose avalanche that occurred on a south facing slope around 1:30 pm (photo). They also mentioned wet slab avalanches were visible in the surrounding terrain. Slab avalanches occurring without a recent load are a clear indicator the snowpack is not adjusting well. The probability of wet slabs pulling out today is fairly low, but it’s something to consider.
Today, a strong surface crust formed by nighttime cooling and ample long wave radiation loss will likely remain intact through the morning hours. If the forecast holds; increasing clouds, strong winds and cooler temperatures will arrive before this crust has a chance to break down. This will help mitigate wet snow instabilities. However, if the storm arrives late, sun exposed slopes could experience wet loose avalanches by early afternoon. Wet snow can change from stable to unstable in a short period of time, so it’s important to pay attention to changing conditions.
Today, the avalanche danger is rated MODERATE.
Doug 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.