Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, March 26 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.
Under sunny skies and light winds, mountain temperatures rose to 32F yesterday but never reached t-shirt warmth. That will change today. Under partly cloudy skies mountain temperatures will rise from the teens this morning into the low 40s by mid-afternoon and drop below freezing tonight. Ridgetop winds are 10-15 mph out of the west to southwest and will remain light. A ridge of high pressure brings warm and calm weather over the next few days.
Wet Snow Avalanche Danger
A bit of sunshine and temperatures rising well above freezing will create loose, wet snow avalanches today. Point release slides from cliffs, rock out-croppings or steep, sunny slopes, have the potential to knock a skier down and drag them into terrain traps. Pinwheels of snow, growing as they roll downhill, is a sign that surface snow is wet enough to slide. The wet snow avalanche danger will rise to MODERATE this afternoon.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone
In general, the snowpack stability is very good. The 8-12 inches that fell late last week is bonding well to the melt-freeze ice crust underneath. Over the weekend I found this in Beehive and Bear Basins (video) and Eric saw this in the Bridger Range. Observations, with the exception of a few slopes near Cooke City, indicate this stability is widespread.
The snowpack is entering a transitional phase this week as warm temperatures permeate into it, melt the upper layers, and slowly warm the entire pack. Above freezing temperatures can change the snow structure quickly. Snow does not like fast change so we’ll be keeping a close eye on the rate of change and duration of temperatures above freezing.
Cornices have grown all winter and are fat and ready for slaughter. Some of the larger ones will weaken quickly as temperatures warm towards freezing. A large cornice fall triggered a steep slope in Frazier Basin in the Bridger Range Saturday night (photo). I expect to see others crack off in the coming days.
For today, the dry snow avalanche danger is rated LOW on all avalanche terrain. A low danger does not mean there are no dangers. Cornices breaking and small avalanches in isolated areas can still happen.
Cooke City
A small natural avalanche was seen yesterday around Goose Lake outside Cooke City (photo). This slide is a red flag that the new snow might not be bonding to the underlying ice crust. Although slides like these are few and far between, it’s worth digging a quick hasty pit or hand pit to see how strongly the snow from last week is sticking to ice. Today, the avalanche danger is rated MODERATE on slopes steeper than 35 degrees and LOW elsewhere.
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.
Take Note:
Our 136th and last avalanche advisory will be on Sunday, April 7th.