2017-18 West Central Montana Avy Conditions: 4/21/18--SECOND final forecast.

[Scott]

Missoula Avalanche
Avalanche Advisory for December 31, 2017

high danger
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The Avalanche warning is terminated this morning. The avalanche danger is HIGH on wind loaded slopes in the West central Montana backcountry. All other slopes are rated CONSIDERABLE. Travel on or under wind loaded slopes is not recommended today. This means careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential to recreate today.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 31, 2017. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 13 F to 26 F in the region. In the Bitterroot winds are 3 mph with gusts of 4 out of the SW. In the northern part of the advisory area, at Point Six, winds are reading 21 mph with gusts of 26 mph out of the WNW. The forecast area received 3 to 4 inches of new snow in the last 24 hours.

We are coming out of a large natural avalanche cycle. Downing Mountain Lodge sent us observations of a natural wind slab avalanche that released on the Thanksgiving crust yesterday. This slide ran 1800 feet, it released around 7800 ft in elevation and ran to 6000 ft in elevation. Snowbowl ski patrol reported very sensitive wind slabs that were 1 to 2 feet in depth.

The primary avalanche problem today is wind slabs. Leeward terrain will have large wind slabs. Look for rounded pillows of snow near ridgelines and recognize signs of instability such as cracking in the surface snow. These slabs will be very sensitive to human triggers. Avoid traveling on or under wind loaded slopes.

The second avalanche problem is persistent slabs. The layer of facets above the Thanksgiving crust has been stressed. This layer has been shown to fail in the last two natural avalanche cycles. This means careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential to recreate today. Look for clues from the snowpack shooting cracks and localized collapsing. Dig a pit on low angle terrain in a safe spot out of runout zones to see how the layers are adjusting to the new load.

The final avalanche problem is storm slabs. These slabs are becoming less reactive as the snowpack adjusts to the weight of the new snow. Look for shooting cracks and try small test slopes with low consequence to see how the new snow is bonding.

Avalanche and Weather Outlook

Our next chance for snow will be in the middle of the week. With the forecast look for the avalanche danger to slowly decrease as the snowpack adjusts to the new snow.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. I will issue a weather update tomorrow January 01, 2018.

Ski and ride safe.



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[Scott]

Missoula Avalanche
Avalanche Advisory for January 1, 2018

considerable danger
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The current avalanche danger is CONSIDERABLE in the West central Montana backcountry. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential to recreate today. Natural avalanches are possible and human triggered avalanches are likely across the region.

Good morning and happy New Year, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 01, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 9 F to 21 F in the region. In the Bitterroot winds are 7 mph with gusts of 12 out of the SSW. In the northern part of the advisory area, at Point Six, winds are reading 24 mph with gusts of 28 mph out of the WNW. The forecast area received 0 to 1 inch of new snow in the last 24 hours.

We are getting reports of skier triggered slides from yesterday. These slides failed on the facets above the Thanksgiving day crust. Skier or rider triggered avalanches are likely.

The primary avalanche problem today is wind slabs. Leeward terrain will have large wind slabs. Look for rounded pillows of snow near ridgelines and recognize signs of instability such as cracking in the surface snow. These slabs will be sensitive to human triggers.

The second avalanche problem is persistent slabs. The layer of facets above the Thanksgiving crust has been stressed. This layer has been shown to fail in the last two natural avalanche cycles. This means careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential to recreate today. Look for clues from the snowpack shooting cracks and localized collapsing. Dig a pit on low angle terrain in a safe spot out of runout zones to see how the layers are adjusting to the new load.

The final avalanche problem is storm slabs. These slabs are becoming less reactive as the snowpack adjusts to the weight of the new snow. Look for shooting cracks and try small test slopes with low consequence to see how the new snow is bonding.

Avalanche and Weather Outlook

Our next chance for snow will be in the middle of the week. With the forecast look for the avalanche danger to slowly decrease as the snowpack adjusts to the new snow.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. I will issue a weather update tomorrow January 01, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 1, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 2, 2018

considerable danger
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The current avalanche danger is CONSIDERABLE on all slopes above 6000 feet in the West central Montana backcountry. Careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential to recreate today. Natural avalanches are possible and human triggered avalanches are likely across the region. All slopes below 6000 feet are MODERATE today.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 02, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 4 F to 20 F in the region. In the Bitterroot winds are 8 mph with gusts of 11 out of the S. In the northern part of the advisory area, at Point Six, winds are reading 21 mph with gusts of 24 mph out of the WNW. The forecast area received 0 to 1 inch of new snow in the last 24 hours.

Matt and I toured near Lolo Pass yesterday. We found the snowpack below 6000 feet to be relatively stable. We have public observations(PB01, PB02) of the storm slab gaining strength. We got reports of natural activity on North aspects above 7000 feet in the southern Bitterroot on the Thanksgiving crust. We also found surface hoar growth; this will be a layer of concern when it gets buried with the next storm.

Wind slabs are the primary avalanche problem. These slabs are gaining strength but still will be likely triggered by a human. Leeward terrain will have large wind slabs. Look for rounded pillows of snow near ridgelines and recognize signs of instability such as cracking in the surface snow.

The second avalanche problem is persistent slabs. The facets on the Thanksgiving crust are reactive on slopes above 6000 feet. We got observations of this layer releasing naturally yesterday in the southern Bitterroot on a North facing aspect. Natural activity is a bullseye clue to instability. The other way to find this layer is to dig a pit in a safe spot out of runout zones and on low angle terrain.

Our next chance for snow will be in the middle of the week. With the forecast look for the avalanche danger to slowly decrease as the snowpack strengthens.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory.Logan will issue a weather update tomorrow January 03, 2018.

Ski and ride safe.

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[Scott]

Current West Central Montana Avalanche Advisory
Posted: Jan 03, 2018 06:29 am
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Missoula Avalanche
Avalanche Special Update – Weather Update – January 3, 2018

norating danger
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Good morning, this is Logan King with the West Central Montana Avalanche Center’s weather and avalanche update for January 3rd, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Temperatures at mountain locations vary from 15 to 31 degrees this morning. Winds at Point 6 are 17mph gusting to 21mph from the W and at Deer Mountain are 8mph Gusting to 12mph. A trace to 4 inches of snow has fallen in the last 24 hours across the region.

Wind slabs remain the primary concern today. The secondary concern is persistent weak layers. Wind slabs have continued to produce avalanches that are stepping down to the facets on the Thanksgiving crust. The combination of a stiff windslab and the added stress of wind loading continues to be able to trigger this weak layer. These avalanches have been large high consequence events and should be treated with respect. Be cautious of wind loaded terrain near ridge lines and keep an eye out for cross-loaded pockets that can sneak up on you.

Light snow this morning will subside and mountain temperatures will be in the low 30’s. Snow looks to return to the area on Friday.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next advisory will be issued tomorrow January 4th, 2018.

Ski and ride safe.

The post Avalanche Special Update – Weather Update – January 3, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory
Posted: Jan 04, 2018 06:12 am
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Missoula Avalanche
Avalanche Advisory for January 4, 2018

considerable danger
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The current avalanche danger is CONSIDERABLE on wind loaded slopes above 6,500 feet in the West Central Montana backcountry. A MODERATE avalanche danger exists on all other terrain. Careful evaluation of terrain and snowpack is necessary to identify areas of concern.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 4th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Winds this morning at Deer Mountain are 9 mph gusting to 12 mph from the SSE. At point six the winds are 13 mph gusting to 15 mph from the SW. Mountain temperatures currently range from the high teens to mid twenties. An additional 1-2 inches of snow accumulated in the last 24 hours.

Travis and I rode to Twin Lakes in the central Bitterroot yesterday. We found stable snow at lower elevations with wind slab concerns continuing at higher elevations. The primary avalanche concern today is wind slabs.

The tail end of the last storm brought strong winds and developed some large wind slabs. Wind slabs are primarily located above 6,500 feet. Avoid terrain that is wind loaded. We observed a few small natural wind slab crowns yesterday and continue to receive reports of wind slabs failing with human triggers and stepping down to the Thanksgiving crust.

The secondary avalanche concern is the deep persistent weak layer on top of the Thanksgiving crust. After the last couple of storms this layer is now buried deep but is reactive when paired with wind slabs. Be very cautious of this layer, the consequences of a slide this deep would likely be catastrophic. Avoid any steep terrain where this layer is suspect including run out zones.

Loose snow avalanches are the final concern today. We observed loose surface snow sluffs yesterday that were small and non threatening. Be aware of terrain traps that increase the consequences of getting caught in a loose snow avalanche. We observed a small windslab that was triggered by a loose snow avalanche and ran through rocks breaking branches and small trees (video).

Light snow showers today and into tomorrow before the next system moves in this weekend. Snow total today will be insignificant but will provide more snow for transport. Avalanche conditions will remain the same through today.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. A weather update will be issued on Friday.

Ski and ride safe.

The post Avalanche Advisory for January 4, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory
Posted: Jan 05, 2018 06:06 am
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Missoula Avalanche
Avalanche Special Update – Weather Update – January 5, 2018

norating danger
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Good morning, this is Logan King with the West Central Montana Avalanche Center’s weather update for January 5th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures across West Central Montana are in the low 30’s this morning with many locations already above freezing. Precipitation has been minimal with a few snotels showing and addition of .1-.2 inches of SWE. Winds at Point 6 are 17 mph gusting to 24 mph from the W. Further south at Deer Mountain, winds are 7 mph gusting to 12 mph from the SSW. Weather conditions will be similar to yesterday until moisture returns to the region late today. The snow level is expected to be fairly high through Saturday morning.

Conditions have not changed much over the last few days and the main avalanche concerns continue to be wind slabs and deep persistent slabs. Wind slab activity continues across the region above 6,500 feet. Deep persistent slabs are hard to trigger but will be high consequence events. Carefully evaluate terrain to identify areas of wind loading and potential trigger zones for deep persistent avalanches.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next advisory will be issued tomorrow January 6th, 2018.

Ski and ride safe.

The post Avalanche Special Update – Weather Update – January 5, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory
Posted: Jan 06, 2018 06:34 am
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Missoula Avalanche
Avalanche Advisory for January 6, 2018

considerable danger
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The current avalanche danger is CONSIDERABLE above 6,500 feet on wind loaded terrain across the West Central Montana backcountry. All other mountain locations have a MODERATE avalanche danger. Cautious route finding and careful snowpack evaluation are needed as very large avalanches are possible in isolated areas.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 6th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Moisture has pushed into the region and primarily fell as rain and is shifting to snow early this morning. Rain line is currently around 5,500 feet and continues to drop. Snotels are reporting between .1 and .4 inches of water overnight. Mountain temperatures are above freezing and in the mid 30’s. Winds are out of the W at Point 6 gusting to 21 mph and sustained at 16 mph.

Matt and I were at Wisherd Ridge yesterday and Travis was in the Southern Bitterroot. We found multiple avalanches with up to 4 foot crowns across the advisory area. These slides happened this week and ran full path, up to 2,000 feet. All of the big slides involved a combination of wind slabs and the Thanksgiving crust.

The main avalanche concern today is wind slabs. Wind slabs are located above 6,500 feet and are focused on the eastern half of the compass but vary depending on local winds. Evaluate terrain to see if slopes are wind loaded before committing to avalanche terrain. Wind slab avalanches also have the possibility to step down to deep persistent weak layers (Video).

Unfortunately the Thanksgiving crust was involved in the majority of the large avalanches observed this week so we can’t put this problem to bed yet. A public observation and all of our observers/specialists have been using the phrasing “low probability, high consequence”. The take away is that the Thanksgiving crust is hard to predict, its hard to trigger in stability tests or as a skier/rider but if fails and you are on/or in the path, the outcome will likely, not be a good one. Seriously consider the consequences of getting caught in a slide involving the deep persistent layers before recreating on or near avalanche terrain.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. A weather update will be issued on Sunday, January 7th.

Ski and ride safe.

The post Avalanche Advisory for January 6, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory
Posted: Jan 07, 2018 06:40 am
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Missoula Avalanche
Avalanche Special Update – Weather Update – January 7, 2018

norating danger
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Good morning, this is Logan King with the West Central Montana Avalanche Center’s weather update for January 7th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures are in the upper twenties this morning and winds are calm. Snow accumulation has been minimal and the advisory area received an additional 0-2 inches of snow since yesterday morning.

The primary avalanche concerns today are windslabs above 6,500 feet and deep persistent slabs. We received a public observation that had multiple pits in the rattlesnake with propagation on the Thanksgiving crust. The layer continues to become harder and harder to trigger but the consequences continue to increase. Avoid terrain where the snow is shallow or has a slab that can step down to this layer.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next update will be issued tomorrow January 8th, 2018.

Ski and ride safe.

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[Scott]

Missoula Avalanche
Avalanche Special Update – Weather Update – January 8, 2018

norating danger
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Good morning, this is Logan King with the West Central Montana Avalanche Center’s weather update for January 8th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Most of the region did not receive snow yesterday or last night, but a few snotels did pick up 1-2 inches. Mountain temperatures this morning are in the upper twenties to low thirties. Winds have increased in the Southern Bitterroot to 14 mph and are gusting to 21 mph from the SE. In the northern portion of the advisory area winds remain calm.

The snowpack continues to stabilize but the deep persistent slab can still be triggered and result in large avalanches. Wind slabs and deep persistent slabs continue to be the main concern. Take the time to identify if these layers are present and what the possibility is of triggering an avalanche. Carefully consider the consequences of an avalanche before traveling on or in avalanche terrain.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next advisory will be issued tomorrow January 9th, 2018.

Ski and ride safe.

The post Avalanche Special Update – Weather Update – January 8, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 9, 2018

moderate danger
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The current avalanche danger is MODERATE in the West Central Montana backcountry. Human triggered avalanches are possible and have the potential to be large in isolated areas. Carefully evaluate snowpack and terrain to identify areas of greatest concern.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 9th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures this morning are just above freezing in the low to mid thirties. Winds are calm at Point 6 and 19 mph gusting to 28 mph from the SE at Deer Mountain. Light showers delivered .1-.3 inches of snow water scattered across the region. More precipitation is expected later today with rain lines around 5,000 feet.

Travis and I were in the Rattlesnake yesterday and Tim and Greg were in the Southern Swans. We all found snow that is continuing to settle along with warm and mild conditions.

The most significant concern this morning are the deep persistent slabs. The Thanksgiving crust and facets continue to heal but have the potential to still cause very large avalanches. This layer continues to gain strength but with the consequences so high it demands respect. Avoid shallow or rocky areas where it may be easier to trigger this layer. Thoroughly consider the consequences of this layer failing before committing to avalanche terrain.

Consequences continue to be the theme today as the secondary concern is loose wet avalanches. Although very small in nature a wet loose slide can pack a punch. Avoid terrain traps where you have the possibility of getting carried into rocks, tress, or gullies where deep burials are possible. Lots of roller balls and wet point releases were observed yesterday and with todays warm temperatures and moisture coming it will be a growing concern.

Wind slabs are the third concern today. Tim reported the presence of large wind slabs in the Southern Swan but wind slabs have slowly been gaining strength over the last few days. Wind slab activity has decreased and with clam winds in the north and minimal snow for transport in the south, growth has diminished. Identify terrain that is wind loaded and carefully evaluate the possibility of triggering a wind slab, especially if there is potential to step down to the deep persistent layers.

A warm wet system is moving into the region later today and into tomorrow morning. Rain lines will be high and a significant load of wet heavy snow is possible. Conditions can deteriorate rapidly with a new heavy load of snow, stay aware of avalanche conditions as they change through the day today.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. A weather update will be issued on Wednesday, January 10th.

Ski and ride safe.

The post Avalanche Advisory for January 9, 2018 appeared first on Missoula Avalanche.



This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but you can use the information we provide to help you make more informed decisions regarding travel in avalanche terrain for the next few days.

Our advisory area includes the Bitterroot Mountains from Lost Trail Pass North to Hoodoo Pass, the Rattlesnake Mountains and the Southern Swan and Mission Mountains near Seeley Lake. Avalanche information for the Lookout Pass/St. Regis Basin is available from the Idaho Panhandle Avalanche Center.

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[Scott]

Missoula Avalanche
Avalanche Advisory for January 11, 2018

high danger
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The current avalanche danger is HIGH in the southern Missions and Swan ranges. Travel is avalanche terrain is not recommended today. A CONSIDERABLE avalanche danger exists across the rest of the West Central Montana Backcountry. Conservative decision making are essential today as conditions look to deteriorate. Widespread avalanche activity is possible and will increase through the day today.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 11th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

The Southern Missions and Southern Swan ranges have taken the brunt of the storm thus far. Snotels yesterday were reporting 11 inches of snow and 1.2 inches of SWE. The addition of another few inches overnight plus more to come today will further stress the snowpack. Temperatures are in the low twenties for the region.

The Rattlesnake and Bitterroot Mountains did not get hammered as hard. Yesterday 4-8 inches accumulated with .4-.9inches of SWE. Overnight an additional 1-4 inches fell in the southern region. Mountain temperatures are in the teens to upper twenties this morning and winds are calm at Point 6 and Deer Mountain with gusts up to 10 mph from the south.

The primary avalanche concern today will be storm slabs, especially in the northern part of the advisory area. A wet and heavy load of snow has accumulated and will be stressing the snowpack. For the southern Missions and Swans, travel in avalanche terrain will not be recommended as widespread avalanche activity is likely today. Snow stability will continue to be poor as a significant load of new snow is expected today and into tomorrow further stressing the snowpack.

Tim and Greg were in the Rattlesnake yesterday and Travis and I went up to Lolo Pass. We found 2-5 inches of heavy wet snow sitting on a newly formed rain crust at lower elevations and sun crusts or surface hoar at upper elevations.

The primary avalanche concern for the Bitterroot and Rattlesnake will be persistent weak layers. A layer of surface hoar formed on cold shaded aspects and a sun crust formed on warm solar affected aspects. The buried surface hoar will be sensitive to triggers today. As the load continues to increase, human triggered avalanches will become likely by the afternoon. The deep Thanksgiving crust continues to heal but will remain suspect for some time, be on the lookout for the possibility of step down avalanches specifically in shallow snow or rocky terrain.

Storm slabs will develop today in the Bitterroot and Rattlesnake as precipitation continues. A rain crust at lower elevations and sun crust on solar aspects at upper elevations will provided a poor bonding surface for the new snow and will be a solid bed surface for snow to move on. Carefully evaluate the bonding of the new snow before entering avalanche terrain. Human triggered avalanches will become likely by mid-day.

With 4-10 inches of mountain snow expected during the day and the potential for up to a foot overnight avalanche danger is increasing across the advisory area. If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next advisory will be issued Saturday the 13th.

Ski and ride safe.

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This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but you can use the information we provide to help you make more informed decisions regarding travel in avalanche terrain for the next few days.

Our advisory area includes the Bitterroot Mountains from Lost Trail Pass North to Hoodoo Pass, the Rattlesnake Mountains and the Southern Swan and Mission Mountains near Seeley Lake. Avalanche information for the Lookout Pass/St. Regis Basin is available from the Idaho Panhandle Avalanche Center.

 

[Scott]

Missoula Avalanche
Avalanche Warning for January 12, 2018

high danger
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An avalanche warning is in effect for the West central Montana backcountry. The current avalanche danger is HIGH. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. Large human triggered avalanches are very likely.

This is Logan King with an avalanche warning for Friday, January 12th, 2017. This avalanche warning is valid for 24 hours. The avalanche warning will either be extended or terminated at 0600 Saturday January 13th.

This danger rating does not apply to operating ski areas and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

A storm continues to wallop the region. Over an inch of snow has been added to the snowpack in the last 24 hours across the region. More than a foot of snow has fallen through the entire advisory area adding 1.1-1.6 inches of water since yesterday morning alone. This bring 2 day storm totals for some locations to over 3 inches of water already.

An extremely heavy load of snow has been added to the snowpack. Avalanche activity will be widespread and has the potential to travel long distances and into flat terrain. Avoid traveling in or near avalanche terrain.

The primary avalanche concern is storm slabs. There is no denying that a hefty load of snow and water have been added to the snowpack but this load is resulting in widespread instability. Adding fuel to the fire are weak layers in the snowpack. Snow is falling on rain and sun crusts or buried surface hoar further enhancing the likelihood of avalanches. A storm that adds this much load this quickly will have the ability wake up the deep persistent layers. The Thanksgiving crust has the potential to become active again, resulting in extremely large avalanches.

The take home today is to avoid traveling in or around avalanche terrain. Conditions will be touchy for the next 24 hours at a minimum. A stressed snowpack, weak layers, bed surfaces, and a deep instability are more than enough evidence to steer clear of avalanche terrain for a few days.

Ski and ride safe.

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[Scott]

Missoula Avalanche
Avalanche Advisory for January 13, 2018

considerable danger
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The Avalanche warning has expired and the current avalanche danger is CONSIDERABLE. Natural avalanches are possible and human triggered avalanche remain likely. Cautious route finding and conservative decision making are essential for backcountry travel today.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for Saturday, January 13th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures are hovering around freezing this morning. Winds are from the WSW at 15 mph gusting to 20 mph. Light snow continued through the night and the area received an additional 2-4 inches of snow over the past 24 hours. The bulk of the snow yesterday was again focused towards the northern half of the advisory area.

Travis and I went to Seeley yesterday and found the storm slab was starting to settle and bond to the older snow surface. We received reports of avalanche activity yesterday that was failing about a foot deep with artificial triggers.

Storm slabs are the primary avalanche concern today. The majority of avalanche accidents happen within 24-48 of a storm, so be skeptical of the snow as the massive load hasn’t had the time needed to settle out yet. We are already seeing signs of bonding in the new snow but with the continued lighter snow it will require a little extra time before it’s no longer a concern. Before you commit to avalanche terrain, carefully evaluate the snow to determine if the new layer is still reactive.

Buried surface hoar will make persistent slabs the secondary concern today. With a very weak layer underneath the heavy load of new snow persistent slabs will be easily triggered if there is a persistent weak layer below the surface. The only way to determine if this layer is present is to take the time to dig a pit and identify if this layer is present. Be wary of slopes that have buried surface hoar and avoid traveling on or below them.

Winds started to develop towards the tail end of the storm creating small wind slabs in isolated pockets. We received a report of a small wind slab that was triggered yesterday. Small isolated wind slabs will continue to develop under light winds as there is plenty of snow for transport. Avoid terrain that has been wind loaded.

Avalanche and Weather Outlook

Active snow showers will continue through the morning but snow fall will be nowhere near what the last few days brought. Avalanche conditions will remain the same through the day today before stability starts to slowly improve through the weekend.

If you are out in the backcountry, please send us your observations, these are very helpful in producing the advisory. Travis will issue the next advisory on Tuesday January 16th.

Ski and ride safe.

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[Scott]

Missoula Avalanche
Avalanche Advisory for January 16, 2018

moderate danger
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The current avalanche danger is MODERATE in the west central Montana backcountry. Human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 15, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 20 F 31 F in the region. In the Bitterroot winds are 17 mph with gusts of 22 out of the SE. In the northern part of the advisory area, winds are reading 6 mph with gusts of 8 mph out of the ESE. The forecast area received 0 to 1 inch of new snow in the last 24 hours.

Logan and I toured in the Rattlesnake yesterday. We found small wind loaded slopes. We discovered a layer of buried surface hoar that propagated in pit tests. We saw several loose wet events from days past and yesterday. We have observations from the southern Bitterroot of small wind slabs and loose wet releases in the afternoon. The storm slabs have healed. The facets on top of the Thanksgiving crust are buried very deep in our snowpack and are unreactive in snow pit tests. Avoid likely trigger points(near cliffs and rock bands) where the snowpack is shallower to decrease the possibility of triggering this layer.

The primary avalanche problem is persistent slabs. There is a layer of buried surface hoar in all our ranges that is reactive in pit tests, not every slope or aspect will have it. The only way to find this layer is to dig a pit and see if this layer is present.

The second avalanche problem is wind slabs. Leeward slopes have small wind slabs. Look for rounded pillows of snow near ridgelines and cross-loaded slopes. Recognize signs of instability such as cracking in the surface snow. These slabs will be sensitive to human triggers.

The final avalanche concern is loose wet activity on southern exposures in the afternoon. When you see roller balls, it is time to move to shadier aspects. These avalanches can entrain a large amount of snow and can have consequences if they knock you down and take you into terrain traps(trees, rocks, and cliffs).

Avalanche and Weather Outlook

Our next chance for snow will be in the middle of the week. Here is the link to weather discussion. With this forecast look for the avalanche danger to stay the same.

If you are out in the backcountry, please send us your observations, these are very helpful in producing the advisory. I will issue the next advisory on January 18, 2018.

Ski and ride safe.



The post Avalanche Advisory for January 16, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 18, 2018

moderate danger
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The current avalanche danger is MODERATE in the west central Montana backcountry. Human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 18, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 24 F 40 F in the region. In the Bitterroot winds are 21 mph with gusts of 31 out of the SSE. In the northern part of the advisory area, winds are reading 11 mph with gusts of 21 mph out of the SSE. The forecast area received 0 to 1 inch of new snow in the last 24 hours.

Tim and I toured in the Rattlesnake yesterday. We found buried surface hoar in our pits. This layer is not on all aspects but can be found throughout the advisory area. I found the Thanksgiving crust to be less reactive in tests. Avoid steep, rocky terrain and slopes with shallow snowpacks. We saw surface hoar growth yesterday, as this system moves into the region this will be the next layer of concern.

The primary avalanche problem is persistent slabs. The buried surface hoar was reactive in some pit tests yesterday. This layer is not on every slope or aspect. To find the buried surface hoar, you need to dig a pit 3 feet down and see if this layer is present and how reactive it is.

The second problem is loose wet. With warm temperatures look for loose wet releases to increase with rain and warm temperatures. If slopes start to have roller balls, it means that it is time to move away from these slopes because the surface snow is becoming unstable.

Avalanche and Weather Outlook

Starting today, we will see warm temperatures and rain to 6000 feet. Temperatures will drop overnight, and snow will return to the mountains. Here is the link to the discussion. With this forecast expect our avalanche danger to increase. We will bury the new layer of surface hoar with this next storm. Expect the buried surface hoar to become more reactive with the additional weight of snow and rain. Look for loose wet activity to increase throughout the day on steep slopes below 6000 feet.

If you are out in the backcountry, please send us your observations, these are very helpful in producing the advisory. I will issue the next advisory on January 20, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 18, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 20, 2018

moderate danger
View Full Advisory »
The current avalanche danger is MODERATE in the west central Montana backcountry. Human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 20, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 14 F to 26 F in the region. In the Bitterroot winds are 3 mph with gusts of 6 out of the SE. In the northern part of the advisory area, winds are reading 9 mph with gusts of 16 mph out of the SSW. The forecast area received 0 to 4 inches of new snow in the last 24 hours.

Logan and I took the sleds to Lolo pass yesterday. Geoff was near Lost Trail pass and, Steve was in the Rattlesnake. Logan and I found a relatively stable snowpack. We saw a very large, rider triggered avalanche that ran on buried surface hoar and stepped down to the Thanksgiving crust near a rock band. Geoff was able to find buried surface hoar, but it did not propagate in tests. Steve was able to get the buried surface hoar to propagate. We got a public observation from the Lolo pass area showing signs of a strengthening snowpack.

The primary avalanche problem is persistent slabs. This layer is not on every slope or aspect. To find the buried surface hoar, you need to dig a pit 3 feet down and see if this layer is present and how reactive it is. There is a rain crust up to 6000 feet with new snow on it. This layer was not reactive in tests but should be investigated by digging a pit.

The second avalanche problem is wind slabs. Leeward slopes have small wind slabs. Look for rounded pillows of snow near ridgelines and cross-loaded slopes. Recognize signs of instability such as cracking in the surface snow. These slabs will be sensitive to human triggers.

This snowpack is a stout Moderate. Many slopes do not have buried surface hoar, but those that do are reactive to triggers. The Thanksgiving crust is still in our snowpack. Though this layer is very hard to trigger, when it goes it is very large. The main take away when dealing with persistent weak layers and deep persistent weak layers in a snowpack are to make conservative choices on terrain. To mitigate the Thanksgiving crust, avoid likely trigger points on slopes where the snowpack is shallower. To combat the buried surface hoar dig a pit. Logan and I saw a very large, rider triggered avalanche that happened in the last week. This picture gives the consequences of triggering the Thanksgiving crust if you trigger another weak layer. Overall the snowpack is getting better, but I still do not trust it.

Avalanche and Weather Outlook

Light snow over the next couple of days. Here is the link to weather discussion. With this forecast look for the avalanche danger to stay the same.

Logan will issue the next advisory on January 23, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 20, 2018 appeared first on Missoula Avalanche.



This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but you can use the information we provide to help you make more informed decisions regarding travel in avalanche terrain for the next few days.

Our advisory area includes the Bitterroot Mountains from Lost Trail Pass North to Hoodoo Pass, the Rattlesnake Mountains and the Southern Swan and Mission Mountains near Seeley Lake. Avalanche information for the Lookout Pass/St. Regis Basin is available from the Idaho Panhandle Avalanche Center.

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[Scott]

Missoula Avalanche
Avalanche Advisory for January 23, 2018

moderate danger
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The current avalanche danger is MODERATE above 6,000 feet in the West Central Montana backcountry. The avalanche danger below 6,000 feet is LOW. Human triggered avalanches remain possible in isolated areas. Heightened avalanche conditions exist on specific terrain features and require careful evaluation to determine if instabilities are present.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 23, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Temperatures this morning are in the teens to low twenties. The area received sporadic snow yesterday and last night. A trace to 2 inches of snow has accumulated over the past 24 hours. Winds are currently light out of the SSW with peak gusts into the low teens.

Tim and Greg were up at Lolo pass yesterday and Travis and I toured in the Rattlesnake. We found a variable snowpack that is continuing to gain strength but still poses concerns. Most of the avalanche problems are isolated and vary greatly across the region and require careful evaluation to identify areas of concern.

The primary avalanche concern continues to be persistent weak layers. The greatest concern in the region are pockets of buried surface hoar. The pockets of buried surface hoar are isolated and not found on all slopes but if present they are reactive and propagate readily in stability tests. The only way to know if this layer is under the surface is to dig and look for it. Avoid traveling in areas that have been identified to be harboring buried surface hoar as avalanches will be easily triggered by this very weak layer.

Wind slabs are the secondary concern today on steep wind loaded terrain above 6,500 feet. Strong winds were reported yesterday at upper elevations and will only increase through the day today. Soft and small wind slabs will be found on leeward terrain and will become increasingly susceptible to failures as they stiffen up and grow today. Avoid terrain that has pillows of wind deposition and obvious lee terrain such as slopes below cornices.

The WCMAC extend our deepest condolences to the friends and family of those affected by the loss of a member of our community. On Saturday afternoon a rider was killed in an avalanche south of Reas Peak on the Caribou-Targhee National Forest near Island Park, Idaho. We will post more information as it becomes available.

Avalanche and Weather Outlook

Intermittent light snow will continue off on and on today until a wet and windy system pushes into the region late today. More information regarding the forecast can be found here. The avalanche danger will remain the same today before if starts increasing tonight as more snow and wind begin to have an impact across the forecast area.

The next avalanche advisory will be issued on Thursday, January 25th, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 23, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 25, 2018

moderate danger
View Full Advisory »
Above 6,000 feet and on wind loaded terrain the current avalanche danger is MODERATE for the West Central Montana backcountry. Avalanches are possible in specific areas and terrain. Careful evaluation of conditions and terrain are essential for backcountry travel today. Conditions will be very dynamic today and will require continual assessment, as avalanche activity will be on the rise.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 25th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Winds are currently in the mid-20’s, gusting to mid-30’s from the South in the Central Bitterroot, Rattlesnake, Southern Missions, and Southern Swan ranges. These areas also picked up 3-6 inches of snow overnight. For the southern Bitterroot only about and inch of snow has fallen and winds at Deer Mountain are 12 mph gusting to 19 mph from the South. Temperatures across the region are right around freezing this morning.

Travis and I rode to Elk Meadows yesterday and Tim toured in the Rattlesnake. We found about 6 inches of new snow near Lolo Pass and observed strong ridge top winds that were actively transporting snow. Small pockets of buried surface hoar are still reactive in stability tests around the advisory area. Today will be marked by change as more snow is added to the snowpack and winds will continue to affect snow stability.

The continued reactivity of the buried surface hoar keeps it at the tops of the list of avalanche concerns for now. The persistent slab is just as reactive as it has been and is developing a good size slab on top, increasing the consequences of this layer failing. The surface hoar is isolated in small pockets mostly on cooler aspects but the only way to identify if this layer is present is to dig. Take the time to dig for and identify this layer when determining where to recreate today.

Wind slabs are the second major concern today and will be a growing concern for the next 24-48 hours. Consistent and strong winds have been observed at upper elevations and near mountain passes and ridges for the past few days, increasing the concern of wind slab avalanches. Wind slabs are growing and with more wind and snow for transport expected, this problem will not be going away anytime soon. Look for signs of wind loading like rounded pillows of snow below ridges and avoid leeward and cross loaded terrain. Carefully evaluate terrain features for signs of wind loading before traveling in or around steep mountain terrain.

Loose wet avalanches are the third concern today but will be somewhat dependent on the progression of the storm today. With mild temperatures and the possibility of sun affecting the snow surface later in the day today, look for signs of increasing instability as the day progresses. Roller balls and heavy surface snow will develop before you start to see small loose wet avalanches. If you start to see signs of loose snow activity change aspects to cooler ones to decrease your exposure.

Avalanche and Weather Outlook

Strong upper elevation winds today will be accompanied by morning snow. More information regarding the forecast can be found here. The avalanche danger will be increasing today especially for the central Bitterroot, Rattlesnake, Southern Missions and Southern Swan ranges.

The next avalanche advisory will be issued on Saturday, January 27th, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 25, 2018 appeared first on Missoula Avalanche.

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 27, 2018

considerable danger
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The avalanche danger for the West Central Montana backcountry is CONSIDERABLE on wind loaded terrain. On non-wind loaded terrain the avalanche danger is MODERATE. Large avalanches are likely in areas that have been wind loaded. Cautious route finding, and conservative decision-making are required to navigate dangerous avalanche conditions.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for January 27th, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

The Rattlesnake down through the central Bitterroot pick up 3-4 inches of snow last night with temperatures in teens to twenties. The southern Bitterroot received about and inch of snow last night with similar temperatures. The North Fork Jocko snotel picked up 1.2 inches of water for the past 24 hours and around a foot of snow. Winds this morning are from the SSE at Deer Mountain and are gusting to 16 mph. Winds at Mt. Sentinel are 12 mph gusting to 20 mph from the S.

The latest round of snow has been exceptionally variable across the region. The northern portion of the advisory area got the bulk of the snow while the southern tip hardly received any. Conditions vary significantly from North to South, strong upper elevation winds are about the only thing that was uniform across the advisory area. I checked on the wind slab development at upper elevations in the rattlesnake yesterday. Above 7,000 feet we found continued strong winds from the west were producing large wind slabs and some high energy soft wind slabs.

The primary avalanche concern today will be wind slabs. Strong winds and new snow for transport have been building wind slabs over the last few days. Yesterday, wind slabs were small with high energy and will be stiffer today and easily triggered above 7,000 feet on leeward terrain. Avoid terrain that has been wind loaded while traveling in the backcountry today and look for signs like wind pillows, cornices, and shooting cracks.

The buried surface hoar is now about 2 feet deep in the snowpack but is still reactive in stability tests. We found this layer to propagate readily with high energy on a shaded aspect with a soft wind slab on top. This layer may be slightly less reactive now but the consequences of a slide continue to increase. The only way to identify this layer is to dig and perform stability tests. Don’t just think about the likelihood of avalanches but consider the consequences of this layer failing before committing to avalanche terrain.

Storm slabs will also be a concern today for areas that received more snow, like the southern Missions and southern Swan ranges. With a foot of lighter snow and over an inch of water, soft storm slabs are possible today. Carefully assess the new snow to determine if it is bonding or if it has formed a suspect slab before traveling on or around avalanche terrain.

Avalanche and Weather Outlook

Light snow and strong winds are expected to continue across the region. The forecast suggests an accumulation of a couple inches each day through the weekend before the next significant system arrives early next week. The avalanche danger will be increasing today as more snow and active winds will further wind slab problems.

The next avalanche advisory will be issued on Monday, January 29th, 2018.

Ski and ride safe.

The post Avalanche Advisory for January 27, 2018 appeared first on Missoula Avalanche

 

[Scott]

Missoula Avalanche
Avalanche Advisory for January 30, 2018

moderate danger
View Full Advisory »
The current avalanche danger is MODERATE in the west central Montana backcountry. Human triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully and identify features of concern.

Good morning, this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for January 30, 2018. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

Mountain temperatures range from 30 F to 38 F in the region. In the Bitterroot winds are 16 mph with gusts of 39 mph out of the WSW. In the northern part of the advisory area, winds are reading 34 mph with gusts of 46 mph out of the West. The forecast area received 0 to 2 inches of new snow in the last 24 hours.

Logan, Steve and I went to the Rattlesnake yesterday to repair the anemometer on the Point Six RAWS station. We saw many loose wet releases in the Rattlesnake. The snowpack is strengthening. There are large wind slabs at higher elevations on leeward aspects. Overnight we had strong winds gusting to 60 mph. The snowpack did not refreeze till 600 am below 6000 feet.

The primary avalanche problem is wind slabs. Over the last 3 days, wind slabs have developed on leeward aspects. Look for rounded pillows of snow near ridgelines and on cross-loaded slopes. Recognize signs of instability such as cracking in the surface snow. Avoid slopes that are wind loaded.

The second avalanche problem is persistent slabs. There is buried surface hoar on shaded aspects and a melt-freeze crust on southern aspects. Dig a pit three feet down and see if you find these layers. Perform a stability test to assess these layers.

Avalanche and Weather Outlook

A cold front is pushing into the area now. We are expected to pick up more snow and have strong winds. See the forecast here. Expect the avalanche danger to increase with these conditions. I will issue the next advisory on Thursday, February 01, 2018.

Ski and ride safe.



The post Avalanche Advisory for January 30, 2018 appeared first on Missoula Avalanche.