GNFAC Avalanche Forecast for Mon Apr 5, 2021

Not the Current Forecast

Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Monday, April 5th at 7:20 a.m. Today’s forecast is sponsored by Montana State Parks and Cooke City Motorsports. This forecast does not apply to operating ski areas.

Bridger Bowl is closed and backcountry conditions exist. There is no avalanche mitigation or ski patrol rescue. Please stay clear of work areas, snowmobiles, chair lifts and other equipment.

Mountain Weather

This morning temperatures are dropping to near and below freezing and will be high 20s to mid-30s F today. Wind is southwest-southeast at 5-15 mph with gusts to 25 mph, and east-northeast in the Bridger Range. Snow is expected around noon today, with some rain possible at lower elevations. Possible snowfall amounts for this storm have a wide range. By morning 2-6” of new snow is likely near Big Sky, Bozeman and Cooke City with 8-12” possible in the higher Madison, Gallatin and Beartooths.

Snowpack and Avalanche Discussion

All Regions

The last four days had temperatures in the 40s and 50s F and the surface of the snowpack barely froze each of the last four nights. The snow will be slow to freeze this morning due to cloudy skies and just barely freezing temperatures. Wet snow avalanches are still a potential hazard, with the addition of avalanches involving new or wind-drifted snow this afternoon depending on how much snow falls.

Decreasing temperatures this morning will help the snowpack freeze and reduce wet snow activity, but some slopes may not freeze or will only have a thin crust before snow or rain falls later today. Avoid travelling on steep slopes where the snow surface is wet and not refrozen. Yesterday we got a report of a natural wet slab in the Main Boulder, outside and adjacent to our advisory area (photo). This shows recent warm temperatures have introduced meltwater deeper into the snowpack and made wet slabs possible (wet slab video). On slopes that do not freeze, the potential for wet slab avalanches will increase if there is rain or heavy snow. The higher you go in elevation, the more likely the snowpack is frozen. Slopes with a thick, supportable crust are generally stable and the main concern will be new snow sliding on these crusts this afternoon if more than a few inches of snow falls, or if it is blown into thick drifts.

See Dave’s video from Beehive yesterday for a discussion on assessing stability during the transition from wet snow to new snow. Today, avalanches are possible and avalanche danger is rated MODERATE.

If you get out, please send us your observations no matter how brief. You can submit them via our website, email (, phone (406-587-6984), or Instagram (#gnfacobs).

Upcoming Avalanche Education and Events

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out:

TONIGHT! April 5, 6:30 p.m., Forecaster Chat with Alex Marienthal, hosted by Uphill Pursuits, “Spring Snowpack and Forecasting Tools”. Link to Join.

The Last Word

We will end regular forecasts next weekend, but avalanches will still be possible through April or longer. Join me TONIGHT for an online talk about strategies and tools to stay safe this spring, at 6:30 p.m. Link to Join.

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