23-24

Date

Wed, 04/03/2024 - 11:10

Activity

Skiing

Snowmobiling

Today we rode from the Fairy Lake parking lot to the motorized boundary above Frazier Basin. We skied both north and south-facing slopes.

Small puddles in the parking lot had a thin layer of ice and the snowpack had a 2-3" surface crust above moist/wet snow. While riding in we saw several wet loose avalanches from yesterday on south and east-facing slopes. From the saddle, we skied dry snow on a north-facing slope to the lake below. At 10:00 AM we saw the first wet loose avalanche of the day. We saw a dozen more over the next hour. By 11:30 the upper 6" of the snowpack had become wet and no longer supportable on foot. We exited the basin up a northerly slope that had been shaded for most of the day. Riding out we saw several fresh wet loose avalanches between Pomp and Hardscrabble Peaks. The only other activity we saw was a small skier-triggered slough avalanche in steep northeast-facing terrain.

Clouds increased by the afternoon and remained there for most of our ride out. Temperatures increased noticeably with any break in the clouds from the strong spring sun.

Region

Bridger Range

Location (from list)

Frazier Basin

Observer Name

Zach Peterson

Wet Slab on the Fin

Date

Wed, 04/03/2024 - 10:10

Activity

Skiing

Toured out into Lower Hayden today to look around. Lots of wet loose avalanches on all aspects by noon. And by the time I came back down the hill, the Fin had slid. It likely happened sometime between 10:30 and 1:30 today. It doesn’t look super deep, but it’s hard to say for sure. I’d guess around 2 feet deep.

Region

Cooke City

Location (from list)

Republic Mountain

Observer Name

Noah Mattes

GNFAC Avalanche Forecast for Wed Apr 3, 2024

Snowpack and Avalanche Discussion

Yesterday was warm in the mountains and we had wet avalanches. Today will be even warmer. Temperatures are forecasted to hit the upper 50s F in the Bridger Range and upper 40s F around Island Park, West Yellowstone and Cooke City. All ranges will see wet avalanche activity today.

The mountains around Bozeman and Big Sky did not freeze last night. High elevations (10,000 feet or more), north facing slopes and cold drainages are the exception, which Dave talks about in his <a href="https://youtu.be/WJWxsKW0flc">…; from the Bridger Range yesterday. Without a freeze, today’s blazing April sun will wet and melt the surface snow very quickly. Wet avalanches will slide on a crust 1-2 feet under the surface. By late morning sunny slopes will be wet, gloppy, and ripe to slide. Stay out of avalanche terrain and be especially cognizant of those below you because wet avalanches can run far.

Cornices at the ridgelines will also be melting and sagging and breaking in the heat. These behemoths are great triggers (<a href="https://www.mtavalanche.com/images/24/large-cornices-along-lionhead-rid…;).

Wet avalanches sliding down the hill or cornices breaking may trigger deep and big slides. A thin layer of weak, faceted snow is buried near this upper ice crust and can avalanche. Dave found this in Island Park on Monday (<a href="https://youtube.com/shorts/LPB5N_bAPco"><span…;) and yesterday, Ian and I saw a small slide that broke on this layer in Lionhead (<a href="https://youtube.com/shorts/SIglDcDu-MU?feature=share"><span…;). Even deeper are facets near the ground. Although buried under multiple feet of snow, wet avalanches or water percolating through the snowpack or cornice falls, are all possible triggers.

Without an overnight freeze, plus clear skies, only light wind and temperatures forecasted to be exceptionally warm, the mountains around Bozeman and Big Sky will see the avalanche danger rise from MODERATE to a wet snow danger of HIGH.

In the mountains around Island Park, West Yellowstone and Cooke City, breezy conditions and freezing temperatures overnight will delay wet avalanche activity. The avalanche danger will start as MODERATE and rise to a wet snow danger of CONSIDERABLE.

Read more about GNFAC Avalanche Forecast for Wed Apr 3, 2024

Upcoming Avalanche Education and Events

Hyalite Road Closure: Hyalite road is closed to ALL MOTORIZED VEHICLES until the morning of May 16. This is a regular annual road closure to reduce road damage during the spring thaw. Bicycle and foot traffic are allowed. Contact the Bozeman FS Ranger District for more info.

Weather and Avalanche Log for Wed Apr 3, 2024

Read more about Weather and Avalanche Log for Wed Apr 3, 2024

At 4am: Bridger 36F, Shower 29F, Big Sky 31-36F; below freezing in south

Read more about Edge of Truman Profile - 2 April 2024

Bridger Range, 2024-04-02

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Read more about Large Slab Avalanche behind the Nose

A large slab avalanche behind the Nose. Photo: GNFAC

Avalanche Details: Large Slab Avalanche behind the Nose

Bridger Range, 2024-04-02

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Snowmo triggered small slide at Lionhead

Lionhead Ridge

Lionhead Range

4/1/2024

Code

SS-AM-R1-D1.5-O

Aspect

Latitude

44.71450

Longitude

-111.31800

Notes

On 4/2/24 we saw a small slab avalanche that occurred since this weekend's snow. It appears to have been triggered by a snowmobile yesterday (4/1/24). It broke 10" to 2 ft deep, 50 ft wide, and ran ~50 vertical feet. It broke on a thin layer of facets beneath the new snow.

Number of slides

Number caught

Number buried

Avalanche Type

Soft slab avalanche

Trigger

Snowmobile

R size

D size

1.5

Bed Surface

O - Old snow