GNFAC Avalanche Forecast for Thu Apr 4, 2019

Not the Current Forecast

Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Forecast issued on Thursday, April 4th at 6:45 a.m. Today's forecast is sponsored by Grizzly Outfitters in partnership with Friends of the Avalanche Center. This forecast does not apply to operating ski areas.

Mountain Weather

Overnight the mountains near Big Sky received 2-4” of snow while the rest of the forecast area picked up a trace to one inch. This morning, snow has stopped and temperatures are in the 20s to low 30s F. Winds are blowing 15-30 mph out of the west-southwest. Today, temps warm into the upper 30s to low 40s F under partly to mostly cloudy skies. Winds continue to blow 15-30 mph out of the west-southwest. The mountains could see a trace to one inch of snow by tomorrow morning.

Snowpack and Avalanche Discussion

All Regions

In many areas, temperatures barely dropped below freezing overnight, which will allow the snow surface to soften quickly as the day warms. This will increase the potential for small wet loose avalanches in steep terrain (video). Wet roller balls and pinwheels are signs the surface snow is becoming weak and unstable. Soft-slushy snow deeper than a boot top also indicates the surface snow is losing strength. Managing this problem isn’t difficult. Move to shadier aspects or away from steep terrain if the surface snow is becoming soft and damp. Fortunately, increasing clouds and breezy conditions will help limit wet loose avalanche activity today.

A secondary concern is new snow instabilities, specifically in the northern Madison Range. This area picked up 2-4” of snow overnight, which increases the potential for small wind slabs and loose snow avalanches (video). The new snow came in warm and should be well bonded to the old snow surface. However, the new snow will move easily under the influence of warmer temps and direct sun (video). Both dry and wet loose avalanches will be possible in steep terrain, but these will be relatively small and easy to manage. Isolated wind slabs are an additional concern on upper elevation slopes loaded by west-southwest winds (photo). If you’re gunning for high alpine objectives today, watch for this problem before committing to high consequence terrain.

Today, Generally safe avalanche conditions exist and the avalanche danger is rated LOW. Remember – LOW danger does not mean NO danger. Small avalanches remain possible in isolated areas or extreme terrain.      

If you get out and have any avalanche or snowpack observations to share, contact us via our website, email (, phone (406-587-6984), or Instagram (#gnfacobs).

Island Park

Watch for small wet loose avalanches in steep terrain. Wet roller balls and pinwheels are signs the surface snow is becoming weak and unstable. Move to shadier aspects or away from steep slopes if signs of instability are present. Watch for isolated wind slabs on upper elevation slopes facing north through east.
The Last Word

The Hyalite road is closed to motorized travel until May 16th. Bike and foot traffic is allowed.

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