Good morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Forecast on Monday, March 28th at 7:00 a.m. This information is sponsored by Yellowstone Club Community Foundation and Montana State Parks. This forecast does not apply to operating ski areas.
Yesterday temperatures reached mid-40s to high 50s F, and this morning temperatures are high 30s to low 40s F. Wind has been southwest at 5-20 mph with gusts of 25-50 mph. Today will be partly sunny with increasing clouds and southwest wind increasing to 15-25 mph this afternoon. Temperatures will reach high 40s to mid-50s F. Tonight, a cold front will bring cooler temperatures and a few inches of snow during the day tomorrow.
Very dangerous avalanche conditions exist today. Large, destructive wet snow avalanches are likely and will occur naturally or can easily be triggered by a person. Today will be the sixth in a row with temperatures well above freezing. The snowpack did not freeze or only froze slightly the last five nights in a row, with last night being the warmest yet. Melt-water is flowing downward through the previously dry snowpack. When water pools on weak layers or crusts it can make the snowpack unstable and create wet slab avalanches. Where the snowpack lacks layering to create slabs, wet loose avalanches as deep as the entire snowpack can fail and be equally destructive.
Yesterday, ski patrols at Bridger Bowl, Big Sky and Yellowstone Club observed widespread natural wet slabs and wet loose activity in closed terrain (photos). Dave drove up Bridger Canyon and saw wet slabs in Argentina Bowl (details and photos) and full depth wet loose slides north of Ross Peak (details and photo). On my drive into Cooke City I saw a couple natural large wet slabs (photo), and many wet loose avalanches (photo). Recent activity has been widespread on slopes that receive sunshine. Today on higher, shadier slopes melt-water will be hitting weak layers for the first time, and large wet avalanches are possible on slopes facing any direction.
Plan to avoid steep slopes today. Consider what terrain is above you and avoid areas below steep slopes where natural wet avalanches could deposit deep, heavy debris piles. Without a good refreeze last night the snowpack will be unstable as soon as the sun shines this morning, human triggered avalanches are likely and avalanche danger is CONSIDERABLE. As temperatures rise to 50-60 F today, large natural wet avalanches will be likely and danger will rise to HIGH.
If you get out, please send us your observations no matter how brief. You can submit them via our website, email (firstname.lastname@example.org), phone (406-587-6984), or Instagram (#gnfacobs).
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This article in the Billings Gazette highlighting Dave’s January accident, shoulder injury and rescue is worth your time. Plan ahead and prepare for dealing with an injury in the backcountry and think about how you’d call for outside help.