Northern Gallatin

We toured up to Flanders Mtn. to take down the weather station for the season (before the road closes on Monday, Apr 1). The main observation is a big, deep 2-6' deep avalanche that broke 300-500' wide in weak snow at the bottom of the snowpack. Photos and video attached. It broke across two separate start zones and included a lower angle ridge (still around 30 degrees) in between that slid. E-NE aspect at 9,800'. HS-N-R3-D3-O. 

Next to the avalanche debris there was 1-2" of new snow on a thin melt-freeze crust, and the debris seemed to have around 3" of new snow on it. Minimal evidence of recent wind.There was a trace of new snow in the parking lot, 3-6" on most of the trail, I think from the last couple days, and places up high had 10-12" of recent snow where the sun hadn't affected snow from earlier in the week. Today wind was calm with sunny skies becoming partially obscured with light snow showers. We also saw one small dry loose slide in the new snow on a steep north facing slope, and a variety of older crowns including wind slabs near the ridge and one 2-3' deep crown below some cliffs.

Skied Hyalite and Divide peak today. Snow conditions were extremely variable, ranging from undisturbed powder, to wind slabs and sun crusts. No bullseye signs of instability outside of the new snow (i.e. on the deep slab layer).

In the recent snow there was some localized cracking in dispersed windslabs, rollerballs coming off steep solar aspects, and two old windslab releases in the summer trail bowl off Hyalite. These slides probably released either before or during the most recent wind/storm event, as the start zones were both partially refilled. The larger of the two was noticeably older than the other, with the start zone and debris deeply covered. Both were R1/D1, naturally triggers, with crowns no deeper than half a meter directly under the cornice. No cornice fall seemed evident near either crown.

New snow that was sheltered from the wind and sun showed no signs of instability, and the weather consisted of light winds with periods of interspersed graupel and sun. Weather and obvious wind affects looked similar across the range.

From obs: "Spotted this big guy on the east face of Blackmore today. Seemingly natural and I believe it occurred in the last 36 hours or so. Debris had last nights snow on it. I’d estimate it at D2." Photo: E. Heiman

From obs: "Spotted this big guy on the east face of Blackmore today. Seemingly natural and I believe it occurred in the last 36 hours or so. Debris had last nights snow on it. I’d estimate it at D2. " Photo E. Heiman

Skiers on 03/29/2024 saw this avalanche on the N face of Hyalite Peak from Divide Cirque. This avalanche likely occurred in the last 24 hours. Photo: E. Webb 

On 03/29/2024 skiers saw this recent avalanche on a NE aspect in the Divide Cirque at 9800'. This likely happened in the last 24 hours. Photo: E. Webb