Good Morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Sunday, March 25 at 7:30 a.m. Montana Ale Works, in partnership with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
At 4 am mountain temperatures are in the mid to high 30s F with the exception of the Madison Plateau Snotel site which is recording 29 degrees F. Winds are blowing out of the SSW at 10-20 mph. Today, a southerly flow will pump warm air into southwest Montana. Daytime highs will range from the mid-40s to low 50s F. Skies will be partly cloudy in the north and mostly cloudy in the mountains around West Yellowstone and Cooke City. Winds will continue to blow 10-20 mph from the SSW.
WET SNOW AVALANCHE DANGER
The lack of freezing temperatures overnight combined with above average temperatures today will make wet snow avalanches a serious concern. Sun exposed slopes, specifically those with south and west aspects will be the most prone to wet snow instability. Today, the wet snow danger will start out LOW but could rise to HIGH by this afternoon.
The Bridger Range:
The snowpack in the Bridger Range is feeling the heat. Over the past few days warm temperatures have created conditions resembling a backcountry slip and slide. On Friday a large wet slab pulled out naturally just west of Bridger Bowl (photo). This avalanche occurred one day after a large human triggered slide north of Ross Peak (photo). These two events follow a large avalanche cycle that took place early last week.
Yesterday, Mark and I visited the site of the human triggered slide that took place on Thursday. We found a shallow snowpack with a terrible structure (video). The top 2-3 feet is comprised of a dense slab which is resting over weak facets near the ground. This problematic weak layer is now becoming saturated with free moving water and is rapidly losing strength. I expect more natural wet slabs to occur over the next few days.
Today, continued warm temperatures will keep the snowpack greased an unstable. The avalanche danger will start out CONSIDERABLE but could rise to HIGH by this afternoon.
The Gallatin Range Madison Range Lionhead area near West Yellowstone:
The lack of an overnight freeze combined with warm temperatures today will quickly soften the snow surface. Wet loose avalanches are today’s primary concern. Point releases and pin wheels will be obvious clues the surface snow is becoming unstable. Southerly aspects will be most prone to wet snow instability. However, all slopes at mid to low elevations will be susceptible. Today, avoiding confined terrain such as couliors or gullies is recommended.
A secondary concern will be avalanches breaking on faceted layers buried deep in the pack. It has only been six days since the end of largest avalanche cycle of the season (photo, video). This is not enough time to instill trust and confidence in these problematic layers. Although the probability of triggering an avalanche on deeper layers will decrease a little each day, the consequences remain severe.
Today, triggering a slide in steep terrain remains likely and the avalanche danger is rated CONSIDERABLE on slopes steeper than 35 degrees. Less steep slopes have a MODERATE avalanche danger.
The mountains around Cooke City:
The mountains around Cooke City have the deepest and most stable snowpack in our advisory area. The lack of widespread persistent weak layers combined with cooler temperatures has helped to keep avalanche activity to a minimum.
Today, wet loose avalanches are the primary concern. Sun exposed slopes, specifically those at mid to low elevations will be most susceptible to wet snow instabilities.
Today, the avalanche danger is rated MODERATE.
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.