Trip Planning for Northern Gallatin

Cold temps and sunny days starting to create some surface hoar forming seen on the primary ridge of big Ellis. Surface hoar was less widely distributed on the primary ski zone but was present all along the top of the ridge. Photo: K Gordon 

I went skate skiing up Sourdough Canyon today. The trail intersects many south and southwest-facing avalanche terrains that generally do not have much snow coverage due to their exposure to the sun. 

However, the snowpack is much deeper than normal in the Gallatin Valley and in the low-elevation mountains around the Valley, and these slopes make me nervous, especially because they would impact a trail that sees heavy use by people who do not intend to expose themselves to avalanches and who are not prepared for avalanche rescue. 

Currently, 2.5 to 4 feet of snow is in the terrain near the trail. 

Photo: GNFAC

I went skate skiing up Sourdough Canyon today. The trail intersects many south and southwest-facing avalanche terrains that generally do not have much snow coverage due to their exposure to the sun. 

However, the snowpack is much deeper than normal in the Gallatin Valley and in the low-elevation mountains around the Valley, and these slopes make me nervous, especially because they would impact a trail that sees heavy use by people who do not intend to expose themselves to avalanches and who are not prepared for avalanche rescue. 

Photo: GNFAC

At the base of G2 I triggered a 3 inch x 100 foot soft slab. Photo: D Chabot

Most notable test result was ECTP16 down 35 cm on a layer of surface hoar. Photo: E Heiman

Most notable test result was ECTP16 down 35 cm on a layer of surface hoar. Photo: E Heiman

Three to four inches of new snow from yesterday sat on top of the dust layer that got deposited across most of the forecast area on Monday and Tuesday. Photo: GNFAC

There was evidence of several R1-2/ D1-2 wind slab avalanches that likely ran this weekend on the east face of Blackmore. Photo: GNFAC

Elephant Mountain and the summer trail area were scoured down to the tundra. Photo: GNFAC

I went for a walk up the main fork of hyalite today and observed a very dirty snow surface from the strong SW winds. Photo: Anonymous

 The cornices are growing rather large from the recent wind. Photo: Anonymous

Lots of wind transport filling in the skin track between laps and creating light reactive slabs ~5” deep in places (see photo) primarily out of the west but generally inconsistent in direction. Photo: E Kiesz

From obs: "Wind was rocking in alpine today, fresh windslabs forming and naturally releasing. I could make out 3 on E face, but rough vis with blowing snow. Exposed terrain in alpine had about .5” ice crust from yesterday’s sunshine.

This slab (in pic) released around 11-noon-ish." Photo taken 1/31/25

Large surface hoar across a variety of elevations and aspects at Lick Creek. It was 2-5mm large and present on almost all flats and non-solar aspects. Photo: W Hubbard 

Crown of a wind slab avalanche from the saddle of Blackmore. Photo: Anonymous

I skied forward maybe 5 feet and broke off a wind slab around 20 feet wide and five feet below me. Shifting my weight right after that the snow below me also broke and slid away. Photo: Anonymous

I broke off a wind slab around 20 feet wide and five feet below me. Shifting my weight right after that the snow below me also broke and slid away. Photo: Anonymous

A wind slab avalanche on east facing slope in hyalite. Photo: D Moeser

Very touchy storm slabs formed throughout the day. 6-8” deep by 3pm. low density snow/slab but very fast moving.Photo: R Griffiths

Very touchy storm slabs formed throughout the day. 6-8” deep by 3pm. low density snow/slab but very fast moving. Photo: R Griffiths

Today, we traveled into the Maid of the Mist basin and up and along the Palace Butte ridgeline.  Although temperatures have warmed up significantly since the weekend, strong winds kept conditions frigid. Winds blew plumes of snow off the high peaks and at ridgelines, gusting 50-60 mph. Photo: GNFAC

Winds blew plumes of snow off the high peaks and at ridgelines, gusting 50-60 mph. Photo: GNFAC

Winds blew plumes of snow off the high peaks and at ridgelines, gusting 50-60 mph. Photo: GNFAC

From Obs. "Wind was swirling in Maid of the Mist yesterday, mostly upslope winds that were transporting snow, but inconsistently and were difficult to predict where they were loading. We did not find widespread wind loading, but did get a very small windslab to release just below the top of the ridge (max 3-4" thickness, see image)." Photo: C. Avis

We skied to the top of Mt. Ellis via the ridge from the north. There was light wind on the ridge, otherwise calm. Snowing steadily this morning and tapered off by noon-1pm with skies clearing after noon. There were 2-4" of low density new snow. We dug a pit off the ridgeline on a northeast facing slope at 7,800' and one pit at the top of the burned slope, east facing at 8,100'. Profiles attached.

The first pit had an ECTX and the second had propagation with extra force. There were 2mm facets 30cm off the ground in both pits which were slightly softer in the higher pit. Snow depth was 3-4 feet up high and around 2 feet lower in the thicker trees and along the trails.

Observed a fresh slide on the north side of Mt Blackmore, crown was already filling in, but looked to be a foot or two deep in steep rocky terrain to the skiers left of the north couloir. Photo: S Jonas

Lots of snow moving around in Hyalite this morning! Strong winds were moving snow at/above treeline, Lee aspects getting loaded. Photo S Jonas

Saw cracking of cornices on the ridgeline NE of Mount Blackmore. Just a little nudge released a significant portion. Photo: T Miller 

Snowpit from the top of Tyler's slope in Beehive Basin, W facing, 9200 ft. This is representative of an area with thin snow that is weaker

Probably already reported...but touchy storm slabs on Mt Blackmore. Attached is a photo of a natural from the approach, at the switchbacks to the upper basin.

Photo: Anonymous

Wind slab Blackmore south bowl - 10 Jan 2025

Wind slab along Blackmore trail. Good clue before we got above treeline where more wind was blowing and moving snow

We triggered this wind slab by triggering a smaller one above it while descending the NE ridge of Blackmore. 
~10-12" deep and 25' wide

Big wind slab on N face of Mt Blackmore. We watched it cut loose at 14:25 from cornice fall.

Good news is that it didn't trigger a deeper slide.

Snow on a post along the Blackmore trail shows how much snow has been falling. I suspect the slow and steady nature of snowfall is what allowed it to do this.

Storm slab avalanche that broke about 400 ft wide at 9200 ft in a ENE facing sub-cirque of Blackmore

Two storm slab avalanches on the east face of Blackmore 8-10 inches deep. One of them ran down the normal skin track.

image of snowpit from Mt Blackmore, NE facing, 9185', HS almost 5 ft

Skiers in the Main Fork of Hyalite Creek drainage spotted this crown below the upper cliffs on the Maid of the Mist. Photo: Anonymous