This is Ian Hoyer with the avalanche forecast for Tuesday, March 18th, at 7:00 a.m. sponsored by Spark R&D and Highline Partners. This forecast does not apply to operating ski areas.
AVALANCHE WARNING
Issued Tuesday, March 18, 2025 at 0500
The Gallatin National Forest Avalanche Center has issued an AVALANCHE WARNING for:
- The Centennial Range near Island Park.
- The Lionhead area near West Yellowstone.
- The Mountains around Cooke City.
Continued heavy snowfall combined with strong winds makes for HIGH avalanche danger. Large, deadly avalanches will be happening and can run far distances. Avoid any slope steeper than 30 degrees, and avoid being in avalanche runout zones.
This warning will expire or be updated by 6:00 a.m. on Wednesday, March 19, 2025.
24-Hour Snowfall Totals at 6 am:
Lionhead and Island Park areas: 8-10” with 0.8-1” of snow water equivalent (SWE)
Cooke City: 5” (0.5” SWE).
Madison Range: 3-4” (0.4-0.6” SWE).
Bridger and Gallatin Ranges: 1-2” (0.1-0.2” SWE)
This morning, temperatures are in the teens and 20s F. Winds are 10-15 mph out of the north and west with gusts of 20-30 mph.
Snowfall will continue today in Cooke City and the northern Madison and northern Gallatin Ranges. Another 4-8” are expected in Cooke City by nightfall, with 3-5” near Big Sky and in Hyalite. At most an inch or two will fall elsewhere. Winds are forecast to increase this morning, especially in the southern ranges, where they will be 30-40 mph out of the northwest. High temperatures will be in the teens and 20s F.
Avalanche Warning
Natural and human triggered avalanches are likely today. Heavy snowfall continued yesterday near Island Park and West Yellowstone. Snow totals were a little less in Cooke City yesterday, but heavy snowfall will continue there today. 3-4 ft of new snow have fallen since last Thursday. Large, natural avalanches have been breaking and will continue to break today. Yesterday, Dave saw many large natural avalanches along Lionhead ridge (video).
Very strong winds have drifted snow at all elevations. Strong winds will pick back up again this morning, drifting the snow that fell since the last round of intense winds on Sunday night.
Storm Slab, Wind Slab and Persistent Slab avalanches could all break today, but the specific weak layers and types of avalanches don’t matter - any of them will be large enough to kill or seriously injure a rider or skier. Even non-windloaded slopes without persistent weak layers have the potential for deadly slides.
Avoidance is the only safe option. This means avoiding travel on slopes steeper than 30 degrees and also on lower-angle terrain in the runout zones beneath avalanche paths.
The avalanche danger is HIGH.
Human triggered avalanches are likely today in the Bridger, Southern Madison and Southern Gallatin Ranges. Wind Slab and Storm Slab avalanches are the primary concerns today. Persistent Slab avalanches are also possible near West Yellowstone.
Avalanches are most likely to break on slopes where the new snow has been drifted into even deeper and stiffer slabs, but Storm Slab avalanches could also break on slopes without wind effect. A number of natural avalanches were reported yesterday in the northern Bridger Range (observation).
Persistent Slab avalanches breaking 3-5 ft deep on the weak layers buried in late January provide an additional reason to avoid steep slopes in the West Yellowstone area. There has only been one avalanche on these weak lakers in the last couple weeks (video, photo and obs), but the load from recent new snow and wind will make it easier to trigger these slides, so it wouldn’t be surprising to see more of them today.
Avalanche conditions are dangerous and cautious route finding is required today. The avalanche danger is CONSIDERABLE.
Wind slab avalanches breaking 1-2 feet deep are the primary concern today. Look out for visual clues of wind drifting and avoid wind drifts. Cracks shooting out from your skis or sled mean you’ve found an unstable drift and should retreat to lower angled or non-wind effected terrain.
Loose snow avalanches are also possible on slopes that haven’t been wind effected and can run long distances on crusts below the recent snow.
Seek out slopes sheltered from the wind that will have better snow and safer avalanche conditions. The avalanche danger is MODERATE.