23-24

Phenomenal late snowmobiling in Little bear

Date

Mon, 04/01/2024 - 13:05

Activity

Snowmobiling

BZN Snow Rangers rode little bear to check boundary signs and see where closure encroachment issues had been occurring. Boy were we pleasantly surprised to see 10 new inches up high from the previous spring storm cycles which had set up nicely with minimal traffic. Snow was wind affected on high ridgetops but not on less exposed midslopes. Temperatures were below freezing in the morning but by 1400 higher temps and direct sunlight started to cause some roller balls and pinwheeling. We observed no new avalanche activity. There was one pair on a two-seater skandic, and another group of at least two mountain sledders who seemed far above our ability and eluded us despite our best efforts to find them.

Region

Northern Gallatin

Location (from list)

NORTHERN GALLATIN RANGE

Observer Name

Sandy Jett

Recent instability in the new and wind drifted snow

Date

Mon, 04/01/2024 - 11:05

Activity

Snowmobiling

Rode up to maintenance shack then across to East Hotel creek and dug on the south slopes.
From there we rode to upper Hellroaring creek and to below Reas peak and dug another pit. Then we traveled up and around into Jefferson bowl before heading out.

Avalanche activity seen: 5 total

2 appeared to be rider triggered near Reas peak on North aspects that broke within or just below the new storm snow. (D1/D2)

We saw a natural avalanche that broke near Yale creek on a southern aspect, again broke below new snow. (D1)

2 large natural avalanches that broke within the wind drifted snow in Jefferson Bowl.(D2/D2)

Snow depth ranged between 225-275cm in our test pits.

No signs of instability seen on our ride but temperatures were increasing and wet snow activity will likely follow. In our pit above East Hotel we observed the new snow to be bonding well with the old. (ECTN’s 15/17)

In Hellroaring below Reas we observed facets above and below the upper most crust under the new snow and got propagation.(ECTP15)

Travel Advice:

Human triggered avalanches are still possible but it is not unreasonable to explore into avalanche terrain.
However, we suggest digging down about 3’ below the new snow and asses how it is bonding before riding into steeper terrain. As always carry rescue equipment and reduce risks by only exposing one person at a time while others keep watch from non-avalanche terrain.

Region

Island Park

Location (from list)

CENTENNIAL RANGE

Observer Name

Dave Zinn

Conditions Check - Maid of Mist Basin

Date

Sat, 03/30/2024 - 12:20

Activity

Skiing

200 cm snow depth. Soft on top moving to firm, cohesive layers through the pack. Some weak snow near ground.

Region

Northern Gallatin

Location (from list)

Maid of the Mist

GNFAC Avalanche Forecast for Mon Apr 1, 2024

Snowpack and Avalanche Discussion

Sunshine and temperatures above freezing will make wet snow avalanches the main concern. Additionally, a person can still trigger slabs of recent new snow or very large avalanches that break many feet deep on weak layers near the bottom of the snowpack.

On slopes that receive direct sunshine, the recent snow will quickly become wet and easily slide. Loose wet avalanches are likely, and have potential to become large with up to a foot of soft recent snow to entrain. Stay off and out from below steep slopes that receive direct sunshine, especially later in the day. A snow surface that is moist or wet indicates wet snow stability is deteriorating, and it is time to find shadier or low angle slopes.

A person can also trigger dry slab avalanches involving last week’s snow, especially where it was drifted into thicker slabs (<a href="https://www.mtavalanche.com/images/24/windslabs-hyalite-0329"><sp…;, <a href="https://www.mtavalanche.com/images/24/small-skier-triggered-wind-slab">…;). On Saturday in the Lionhead area near West Yellowstone a pow surfer (snowboarder without bindings) triggered and was partially buried in an avalanche that appeared to break below last week’s snow (<a href="https://www.mtavalanche.com/node/31694"><span…;). The recent snow buried a new weak layer, as we saw in Taylor Fork last week (<a href="https://youtu.be/Hmhje2N8Zc4?feature=shared">…;), which might make recently formed drifts or slabs of new snow unstable longer than usual. Before riding steep slopes you should dig down a couple feet to look for weak layers and test for instability.

Very large avalanches that break on weak layers near the bottom of the snowpack have become less likely compared to earlier in the winter, but have the largest consequences and require thoughtful terrain selection to avoid. A couple recent 2-6’ deep avalanches in Hyalite, on Flanders Mtn. (<a href="https://www.mtavalanche.com/node/31691"><span…; <a href="https://youtu.be/BgZINtzwV6o?feature=shared">…;) and Mt. Blackmore (<a href="https://www.mtavalanche.com/node/31672"><span…;), show the lingering possibility to trigger one of these monsters. These could also be triggered from the weight of a smaller avalanche or cornice falls which are possible with today’s sun and warm temperatures. If you ride or cross steep slopes, choose slopes that are not heavily wind-loaded and without trees, rocks, cliffs or gullies that would increase the chances of being injured or killed if you were caught in a slide.

The avalanche danger is MODERATE this morning, and will rise to CONSIDERABLE this afternoon as wet snow avalanches become likely.

Read more about GNFAC Avalanche Forecast for Mon Apr 1, 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 Mon Apr 1, 2024

Read more about Weather and Avalanche Log for Mon Apr 1, 2024

GNFAC Avalanche Forecast for Sun Mar 31, 2024

Snowpack and Avalanche Discussion

Today you can trigger avalanches within or below the snow that fell over the last week, or avalanches that break many feet deeper on weak layers at the bottom of the snowpack.

Yesterday in the Lionhead area near West Yellowstone a pow surfer (snowboarder without bindings) triggered and was partially buried in an avalanche that appeared to break below last week’s snow (<a href="https://www.mtavalanche.com/node/31694"><span…;). Avalanches are possible where the recent snow was drifted into thicker slabs (<a href="https://www.mtavalanche.com/images/24/windslabs-hyalite-0329"><sp…;), or where it buried new weak layers. Unstable drifts are slightly more likely near Island Park where winds were strongest and the most snow fell. On Friday in the Taylor Fork I found a weak layer buried one foot deep which could cause the recent snow and wind-drifts to be unstable (<a href="https://youtu.be/Hmhje2N8Zc4?feature=shared">…;). Identify and avoid steep slopes with recently formed drifts. Before getting onto any steep slope, dig down a couple feet to look for potential weak layers and assess the stability of the recent snow.

Yesterday in Hyalite we saw a recent avalanche that broke 2-6' deep on weak snow at the bottom of the snowpack (<a href="https://www.mtavalanche.com/node/31691"><span…; <a href="https://youtu.be/BgZINtzwV6o?feature=shared">…;). Another 2-4' deep avalanche occurred on Mt. Blackmore during the same timeframe (<a href="https://www.mtavalanche.com/node/31672"><span…;). These show the lingering possibility for a person to trigger a similar very large avalanche. While these massive slides have become less likely compared to earlier in the winter, they have large consequences and require thoughtful terrain selection. If you ride or cross steep slopes, choose slopes that are not heavily wind-loaded and without trees, rocks, cliffs or gullies that would increase the chances of being injured or killed if you were caught in a slide.

Cloudy skies today should prevent the snow from getting wet, and wet snow avalanches are unlikely. If the sun does show, be on the lookout for loose wet avalanches on steep slopes that receive direct sun.

Today human-triggered avalanches are possible and avalanche danger is MODERATE throughout the forecast area.

Read more about GNFAC Avalanche Forecast for Sun Mar 31, 2024

Upcoming Avalanche Education and Events

Hyalite Road Closure: The gate at the bottom of the Hyalite canyon will be locked at 8:00 PM Tonight! Please be sure to exit the canyon before the gate is locked. The road closure applies to ALL MOTORIZED VEHICLES until the morning of May 16.