Regional Conditions for Centennial Range

as of 5:00 am
Today3″ | 9-17 NW
Jan 21 11″ | 10-20 SW
Jan 20 5″ | 5-10 WSW
8775′     1/22 at 6:00
6 ℉
W - 7 mph
Gusts 17 mph
7750′   01/22 at 5:00
13℉
56″ Depth
Bottom Line: The snowpack is poorly supported by 1.5’ of weak, sugary facets on the ground. 10-14” of snow equal to 1-1.5” of SWE since Saturday with strong wind last night, and an unstable snowpack make it easy to trigger avalanches. These avalanche can be 2-3’ deep and propagate hundreds of feet wide. Avoid travel on and underneath steep slopes, including small terrain traps such as creek beds, gullies and road cuts.
Primary Problem: Persistent Weak Layer

Snow Observations- Centennial Range & Lionhead

Centennial Range
Centennials - Montana
Hellroaring Canyon

Yesterday, I skied into Hellroaring Canyon with a group of 6 backcountry skiers staying the night at Hellroaring Hut. While guiding the skiers to the hut, we saw large deposits of avalanche debris in the bottom of major slide paths on west and southwest facing aspects of Mt. Nemesis. It appeared that some of these avalanches were roughly size 1 - 2.5. Numerous creek bottoms and cut banks had also avalanched into Hellroaring Creek. Even some very low angle NW facing gully features had been ripped out. Looking across the valley into the Blair Lake area, I noted only one very small slide on a steep, rocky aspect. I did not have a chance to dig a snow pit, but I did observe numerous huge “whoompfs” while ski touring, and it was obvious that the faceted layer underneath last week’s 6 inches of new snow was failing regularly.

Full Snow Observation Report
Centennial Range
Centennials - Idaho
Centennial Mountains between Reas and Taylor peaks
Incident details include images

We rode this area all day. No one in the group had ever ridden this area, so it was an exploitation day. I dug a pit on a S facing 10* slope at 8564’.
HS 144 with 6 distinct layers, everything above 60cm was fairly consistent, the bottom 60 was JUNK, all large grain facets that were very soft, with little to no cohesion. I was surprised by the failure I got at 132cm, it failed very easily on the shovel shear, and with a CT11. I got an ECTN17 also at 132cm, nothing else. I did a PST just for the sake of killing time at had a 15/end at the 60cm interface. If there is a large enough trigger I have no doubt that the current slab is capable of propagating, and if it does the slide will likely be big. We did not see any avalanche activity while riding or driving in.

Full Snow Observation Report
Centennial Range
Centennials - Montana
Hell Roaring Creek
Incident details include images

Remote triggered several slides from bottom of slope on south facing slope.

Full Snow Observation Report
Centennial Range
Centennials - Montana
Hellroaring Drainage
Incident details include images

Shallow snowpack ~30", west facing terrain around 8200' is faceted except for the top 6 inches. We observed poor structure and fair to good strength due to a lack of distinct layering (its mostly facets top to bottom).

On an east facing slope at 8,300' we observed a slightly deeper snowpack, but still widespread faceting. Poor structure but good strength. During a pit test at this aspect we did not get propogation on any layers (on 1/5/19.) This was all before the most recent round of snowfall however, clearly the facets present a major persistent layer that will cause issues with increased loading.

Full Snow Observation Report
Centennial Range
Reas Peak
Snowmobile triggered avalanche near Reas Peak
Incident details include images

From e-mail:"a snowmobile triggered slide in a S aspect in the Blue Creek Drainage SE of Reas Peak in the Centennials.  No one was caught and no injuries "

Full Snow Observation Report
Centennial Range
Centennials - Montana
Hellroaring Drainage: Huge "Whumphs"
Incident details include images

I was in the Hellroaring Drainage Yesterday, snow depths below 7,000' hover around 18", around 8,000' snow depths increase significantly but are still shallow i.e. less than 30". Witnessed the largest "whoomphs" I have ever felt (that's saying something since last Decemeber/Jan was horrendous), interestingly much of this was felt returning on the same skin track, telling me this is a stubborn layer that may not give right away. The largest was a collapse in a meadow nearly 0.25 miles long.

Full Snow Observation Report
Centennial Range
Give us your observations!
Incident details include images

After last season's two snowmobiler avalanche fatalities on Reas Peak in the Centennial Range we created this web page so riders could get good, relevant information regarding snowpack and avalanches. Although the Centennial Range is not part of the Gallatin National Forest Avalanche Center's forecast area, we are the closest avalanche center and have valuable information to share.

  • The snowpack in the Lionhead area outside West Yellowstone is typically very similar to the Centennial Range. When we issue Avalanche Warnings in Lionhead, the Centennials are also dangerous. Pictures, photos, and observations from the Lionhead area are windows into the conditions in the Centennials.
  • We designed this web page to be a one-stop-shop for anyone riding or skiing in the Centennials.
  • We need your observations to keep everyone safe. Fill out a form and let us know what you found and attach pictures or videos.
  • If you are riding in other parts of southeastern Idaho, go to avalanche.org and find the nearest avalanche center to get updated information. The snowpack and avalanche concerns in regions adjacent to avalanche centers are typically similar:
  • Another great resource for avalanche information can be found at the Adam Anderson Avalanche Project on Facebook.
  • Avalanche Education is paramount to making good decisions. All avalanche education in Idaho is listed HERE.
  • If you would like to sponsor a 1-hour avalanche awareness class for your store, club, or organization, drop us a line. We may be able to accommodate that.

Do not hesitate to reach out if you have any questions or suggestions. This webpage is a work in progress. Email us at mtavalanche@gmail.com

We hope everyone has a safe season!

GNFAC Forecasters:

Doug Chabot
Alex Marienthal
Eric Knoff
Ian Hoyer

Full Snow Observation Report

Avalanche Activity- Centennial Range & Lionhead

Centennial Range
Centennials - Montana
Avalanche activity in the Centennials
Centennials - Montana
SS-N-D2.5-O
Coordinates: 44.5672, -111.5440
Caught: 0 ; Buried: 0; Killed: 0

" Yesterday, I skied into Hellroaring Canyon with a group of 6 backcountry skiers staying the night at Hellroaring Hut. While guiding the skiers to the hut, we saw large deposits of avalanche debris in the bottom of major slide paths on west and southwest facing aspects of Mt. Nemesis. It appeared that some of these avalanches were roughly size 1 - 2.5. Numerous creek bottoms and cut banks had also avalanched into Hellroaring Creek. Even some very low angle NW facing gully features had been ripped out. Looking across the valley into the Blair Lake area, I noted only one very small slide on a steep, rocky aspect. I did not have a chance to dig a snow pit, but I did observe numerous huge “whoompfs” while ski touring, and it was obvious that the faceted layer underneath last week’s 6 inches of new snow was failing regularly. "


More Avalanche Details
Lionhead Range
LIONHEAD AREA
Snowmobiler triggered slide in Lionhead
Incident details include images
LIONHEAD AREA
SS-AMr-R2-D2
Elevation: 9,000
Aspect: SE
Coordinates: 44.7333, -111.3250
Caught: 0 ; Buried: 0

A snowmobiler triggered this small, but deep avalanche as he rode under the slope.

From his email, "We were riding as a group of 5. All with beacons ,shovels, probes and 4 with inflate packs. The hill broke as I was side hilling. I was just ahead of it and not knocked off the sled."


More Avalanche Details
Centennial Range
Hellroaring Creek
Remotely triggered slides in Hellroaring Creek
Incident details include images
Hellroaring Creek
SS-AMr-R3-D2
Coordinates: 44.5494, -111.5080
Caught: 0 ; Buried: 0

A sledder remote triggered several slides from the bottom of a south facing slope in the Centennial Range, Hell Roaring Creek.


More Avalanche Details

Photos- Centennial Range & Lionhead

Displaying 1 - 20 of 20
  • This graph shows snow water equivalent (SWE) by date at the primary SNOTEL sites that we use in the GNFAC region. From October 1st, 2018 to January 12th, 2019. Steeper lines indicate bigger storms and flatter lines indicate periods of little to no snow. A large storm at the beginning of Novermber laid down a 1-3 foot base. Relatively dry and cold weather through November caused much of that snow to become weak. This weak snow was buried by a series of storms. Avalanches were seen during and following many of these storms. During dry weather between storms, more weak layers formed on the surface of the snowpack and were subsequently buried. (Graph created by GNFAC from NRCS provisional data).

  • A snowmobile triggered avalanche that broke during the last week's avalanche cycle at Lionhead. Multiple (5+) Natural and snowmobile triggered slides were reported between 1/7 and 1/9. On 1/6-1/7 the area got a foot of heavy snow followed by strong winds. This loaded an unstable snowpack that is poorly supported by 1.5' of sugary snow on the ground. Avalanches broke 2-3 feet deep on this weak snow, and propagated relatively wide. Photo: GNFAC

  • A snowmobile triggered avalanche that broke during the last week's avalanche cycle at Lionhead. Multiple (5+) Natural and snowmobile triggered slides were reported between 1/7 and 1/9. On 1/6-1/7 the area got a foot of heavy snow followed by strong winds. This loaded an unstable snowpack that is poorly supported by 1.5' of sugary snow on the ground. Avalanches broke 2-3 feet deep on this weak snow, and propagated relatively wide. Photo: GNFAC

  • A snowmobiler triggered a slide in Lionhead on Tuesday, January 8. Photo: D. Mintus

  • A sledder remote triggered several slides from the bottom of a south facing slope in the Centennial Range, Hell Roaring Creek. Photo: B. Marsh

  • A sledder remote triggered several slides from the bottom of a south facing slope in the Centennial Range, Hell Roaring Creek. Photo: B. Marsh

  • Avalanche triggered remotely by a snowmobiler near Lionhead Ridge on January 7, 2019. From email "24 inch crown and about 200 feet wide... on an easterly wind loaded slope"

  • A snowpit on Lionhead revealed two weak layers. One was under wind blown snow; the other was 1.5 feet above the ground on a thick layer of sugary facets. Photo: GNFAC

  • From e-mail: "This was a snowmobile triggered slide in a S aspect in the Blue Creek Drainage SE of Reas Peak in the Centennials.  No one was caught and no injuries as far as I can tell".

  • This avalanche in Airplane Bowl off Lionhead Ridge, is south facing at 9,000'. The avalanche was 1-2' deep, 100' vertical and 150' wide (estimated). It likely broke late Sunday or Monday (12/31), during or immediately after the Avalanche Warning. Weak, faceted snow could not support the weekends snowstorm and there were widespread slides. Photo: GNFAC

  • Collapsing and cracking in Watkins Creek in Lionhead. The snow is weak and collapses like this indicate instability. Photo: B. Rasmussen

  • Collapsing and cracking in Watkins Creek in Lionhead. The snow is weak and collapses like this indicate instability. Photo: B. Rasmussen

  • The snowpack at 9,000' above Hebgen Lake near West Yellowstone is 60-70cm (~2 feet) deep. It is mostly weak, sugary facets and will struggle to support the weight of future storms. Photo: GNFAC

  • From email: "7,500' West facing in the Hellroaring Drainage 12/22/18"

    Photo: S. Hansen

  • A skier reported a recent slab avalanche at Ernest Miller in the southern Madison. This is a good reminder that as you move further south in our advisory area, we are seeing a thinner and generally less stable snowpack. Photo: C. Grote

  • The Lionhead area near West Yellowstone has the shallowest and weakest snowpack in our forecast region. The bottom half of the pack consists of weak, sugary facets. This well developed weak layer produced unstable results in stability tests on any slope that had wind drifted snow. With more snow and wind in the forecast, this area will experience increasingly unstable conditions. Photo GNFAC  

  • Yesterday at Lionhead Ridge near West Yellowstone we found a shallow and weak snowpack. A foot of weak, sugary snow on the ground will create unstable conditions where it is buried by thick drifts of snow, and when the area gets more snow later this week. Photo: GNFAC

  • Snow water equivalent at SNOTEL stations in the GNFAC advisory areas for the 18-19 season to date. Weak layers formed on the surface of the snowpack during the dry weather (flat section of lines), then they were buried by the recent 10-14" of snow (steep increase at end of graph). Image: GNFAC

  • From an email:

    "By and large right side up snowpack. Some small facets below the 11/1 ice crust at the ground, but well bonded snowpack overall. Pit observations consistent with hand pits dug throughout the day touring north out of Bridger Bowl." Photo: M. Zia

Weather Forecast- Centennial Range

Extended Forecast for

10 Miles ESE Lakeview MT

Winter Weather Advisory January 22, 11:00pm until January 23, 11:00pm
Click here for hazard details and duration
Winter Weather Advisory
  • Today

    Today: A 20 percent chance of snow after 4pm.  Mostly sunny, with a high near 17. Wind chill values as low as -10. North northwest wind 9 to 17 mph becoming southwest in the afternoon. Winds could gust as high as 23 mph.

    Mostly Sunny
    then Slight
    Chance Snow

    High: 17 °F

  • Tonight

    Tonight: Snow, mainly after 8pm.  Patchy blowing snow after 10pm. Steady temperature around 14. Wind chill values as low as -5. South southwest wind 15 to 20 mph, with gusts as high as 25 mph.  Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.

    Snow and
    Patchy
    Blowing Snow

    Low: 14 °F

  • Wednesday

    Wednesday: Snow.  Patchy blowing snow. High near 21. Wind chill values as low as -3. South wind 18 to 21 mph, with gusts as high as 30 mph.  Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible.

    Snow and
    Patchy
    Blowing Snow

    High: 21 °F

  • Wednesday
    Night

    Wednesday Night: Snow.  Low around 13. West southwest wind 13 to 16 mph becoming north northwest after midnight. Winds could gust as high as 24 mph.  Chance of precipitation is 90%. New snow accumulation of 1 to 2 inches possible.

    Snow then
    Snow Likely

    Low: 13 °F

  • Thursday

    Thursday: A 40 percent chance of snow.  Partly sunny, with a high near 22. Southwest wind 11 to 18 mph, with gusts as high as 28 mph.  Little or no snow accumulation expected.

    Chance Snow

    High: 22 °F

  • Thursday
    Night

    Thursday Night: A 50 percent chance of snow.  Mostly cloudy, with a low around 16. New snow accumulation of less than a half inch possible.

    Chance Snow

    Low: 16 °F

  • Friday

    Friday: Snow likely.  Cloudy, with a high near 23. Chance of precipitation is 60%. New snow accumulation of around an inch possible.

    Snow Likely

    High: 23 °F

  • Friday
    Night

    Friday Night: A chance of snow before 11pm.  Mostly cloudy, with a low around 12.

    Chance Snow
    then Mostly
    Cloudy

    Low: 12 °F

  • Saturday

    Saturday: Partly sunny, with a high near 22.

    Partly Sunny

    High: 22 °F

The Last Word

The government shutdown and its effects on USFS avalanche centers is highlighted in this article in Powder Magazine.

 


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