2020-21 West Central Montana Avalanche upates: 4/29/2021 END OF SEASON PARTING WORDS

[Scott]

The most recent update will always be the last post in this thread.

West Central Montana Avalanche Center
https://missoulaavalanche.org/

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Oct 23, 2020 02:30 pm Is this email not displaying correctly? View it in your browser.

​

​ Avalanche Special Update – Early Season Update – October 23, 2020 View Full Advisory » This is Travis Craft with an early season snowpack update on Friday, October 23, 2020. Winter is claiming the high country and creeping to the valley floor. The weather predicted for this weekend should put avalanche safety at the front of plans for recreating outside in the mountains. Strong winds and significant snow accumulations will increase the avalanche danger. In the past, there have been several early season close calls and fatalities in Montana involving hunters, climbers, and skiers. Hunters and Climbers: Please keep avalanche safety on your mind as you travel across steep, open terrain. Consider traveling with a partner and carrying rescue equipment. Skiers and Riders: If there is enough snow to ride, there is enough snow to slide! Avalanche preparedness starts now, and even though it is early in the season, you need to stay aware of the potential for avalanches. Early season snowfall creates hazards on avalanche terrain at upper elevations. This tends to be concentrated on wind loaded terrain where more snow will be found. Keep in mind that there are increased consequences this time of year due to exposed rocks, cliffs, and stumps that raise trauma potential. Keep an eye on the weather as early season snowfall may lead to avalanche problems that persist for the entire season. Now is the time to start watching the weather and observing how the terrain begins to fill in. If you see any of these clues signaling dangerous snow conditions, avoid being on or under open slopes steeper than 30 degrees:​ Recent avalanche activity​ Cracking or collapsing snowpack​ Heavy snowfall​ High winds​ Rapid increase in temperature​ Please remember to check the NOAA Backcountry Forecast and share your observations on our public observation page if you head into the backcountry. If you spend time in the mountains during the winter, chances are you will encounter avalanche terrain. Understanding terrain, weather, and snowpack will help you make good decisions and return home safely. To assist you, we offer a wide range of educational opportunities for all backcountry user groups. To view upcoming events and register for winter course offerings, please visit the education page. The West Central Montana Avalanche Center (WCMAC) will update the advisory as the weather dictates and plans to begin issuing regular avalanche advisories with a danger rating in December. Ski and ride safe. The post Avalanche Special Update – Early Season Update – October 23, 2020 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.​

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Nov 24, 2020 09:48 am Is this email not displaying correctly? View it in your browser.

​

​ Avalanche Special Update – Ramping up to the winter season – November 24, 2020 View Full Advisory » This is Jeff Carty with an early season snowpack update on Tuesday, November 24th, 2020. As everyone who has been out skiing and riding knows, there is an above-average snowpack above 7000’. In contrast to last year, the snow arrived early, built good depth, and has consolidated well. This is a good foundation to build on for the winter, and we will most likely avoid the faceting issues we saw last year. Windslab is the main issue currently, especially on higher elevation slopes over 35º. With moderate to strong winds forecasted throughout the week and some fresh snow in the forecast, expect these wind slabs to get touchier and more destructive. Keep in mind that this time of year, the areas that are best to ride are the most likely slide. As we look for slopes with enough snow to cover rocks and early season hazards, we often gravitate to wind loaded areas. Be aware of stiff, hollow sounding snow, fat pillows, and shooting cracks. Check your slope angles and stick to slopes under 35º if in doubt. Below 7000’, snow depths diminish rapidly, and early season hazards are abundant. Below 6000’, there is minimal to no snowpack. The main hazard here is trees, rocks, or whatever is lurking just below the surface. Take care! There has already been a death this year in Alberta due to shallow snow, rocks, and a head injury. This year could be an interesting one with COVID-19. Backcountry use spiked last spring, numbers seem to be up this early season, and backcountry gear sales are skyrocketing. We expect to see more people in the backcountry. While there is enough space in the backcountry for all of us, this could put extra pressure on roadheads where parking is often limited already. Please be respectful of others and private landowners. Increased numbers in the backcountry mean an increased likelihood of accidents, and COVID-19 means higher risk to rescuers and everyone involved. Now is a good time to dial back our risk tolerance and provide larger margins of error to keep everyone safe. If you are new to the backcountry, please get the training required to be safe and avoid avalanches. If you are a seasoned backcountry traveler, remember that techniques change with new research, and our skills can get rusty over time. It’s wise to update and practice yearly. Check out our education page for information on the courses we offer. We need your observations! Please submit them on our public observation page. Everything you send in helps us assess conditions throughout the forecast area. A picture speaks a thousand words. Lastly, look for regular advisories to begin on December 1st, 2020. Ski and ride safe. The post Avalanche Special Update – Ramping up to the winter season – November 24, 2020 appeared first on Missoula Avalanche.​

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 01, 2020 06:45 am Is this email not displaying correctly? View it in your browser.

​

​ Avalanche Advisory for December 1, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is MODERATE in wind loaded terrain and LOW in all other terrain. Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 1, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. Yesterday’s pulse of snow brought up to 8″ in the mountains with the Bitterroot receiving 2″-6″, Lolo Pass 7″, The Rattlesnake 1″, and Southern Missions 8″. Temps ranged from 19º to 33º. Winds were westerly 15mph to 40mph, transporting significant snow onto leeward slopes. Windslab is our main concern on higher elevation wind-loaded slopes. Elsewhere the snowpack is mostly stable. However, variations do exist within the region, approach all slopes with suspicion. Below 7000′ feet, the snowpack is minimal, early season hazards, trees, and rocks are everywhere. Above 7000′, snow depths grow. At upper elevations, they are at or above average and mostly stable conditions exist. However, this base is starting to change with the high pressure we’ve had and will continue to change with the fair weather forecast for next week. We are starting to see near-surface faceting in the upper 10″ and faceting grains below the rain crust, about 15″ from the ground. While these haven’t adversely affected the snowpack’s strength yet, they are something to keep an eye on. With an extended period of high pressure, we could see further faceting of the snowpack. This could undermine the foundation that the rest of our winter’s snow lands on. In addition to facets within the snowpack, there is surface hoar to be aware of as well. Yesterday, extensive surface hoar was present at Lolo Pass and the Southern Bitterroots. It is probably present in other areas as well. High pressure and the inversion forecast for next week will likely lead to widespread surface hoar growth throughout the region. This will be a concern when the next storm lands on this very weak layer. The bottom line: Above 7000′, we have a mostly stable snowpack. Fresh snow and wind have created wind slabs on steep leeward terrain. Avoid wind-loaded slopes greater than 33º. Continue to practice safe travel protocols in case you find an exception to a generally stable snowpack. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Below 7000′, the snow mostly lacks the depth for decent skiing or avalanches. High pressure has weakened the snowpack with faceting and created surface hoar. It will continue to do this through the rest of the week. These layers will be important to take note of as they will affect stability with subsequent snowfall. Please help us track these layers by submitting an observation if you get out in the backcountry. Ski and ride safe The post Avalanche Advisory for December 1, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 03, 2020 06:46 am​ Is this email not displaying correctly? View it in your browser.​

​ ​

​ Avalanche Advisory for December 3, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is LOW Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 3, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. There has been no new snow since Monday. Temps have ranged from 17º to 42º. Winds were westerly 8mph with gusts to 20mph. Remember that low danger does not mean no danger. Windslab may still be an isolated issue on high elevation wind-loaded slopes greater than 35º. The snowpack is mostly stable. However, variations do exist within the region, approach all slopes with suspicion. Isolated slopes in the Swans have a buried, but apparently well-bonded layer of surface hoar, down 10″. Other pockets of shallowly buried surface hoar likely exist throughout the forecast area. Solar warming was strong on southern aspects and rollerballs were forming above 8000′ yesterday. With strong inversion temperatures and sun, watch for wet loose avalanches late in the day. Move to shaded aspects as the snow heats up. Below 7000′ feet, the snowpack is minimal, early season hazards abound. The snowpack will be shrinking this week, expect more hazards to appear. Above 7000′, snow depths grow. At upper elevations, they are at or above average and mostly stable conditions exist. However, this base is starting to change with the high pressure we’ve had and will continue to change with the fair weather forecast until Monday or Tuesday. We are starting to see near-surface faceting in the upper 10″ and faceting grains below the rain crust, about 15″ from the ground. The lower layer is still showing high strength in stability tests but we are beginning to see planer fractures. This is something to keep an eye on. With an extended period of high pressure, we could see further faceting of the snowpack, although the warm temperatures in the forecast should slow it down. Areas with a shallower snowpack will be more susceptible to faceting. In addition to facets within the snowpack, there is surface hoar to be aware of. Cold, clear nights with mild winds, as we are currently experiencing, are perfect for surface hoar growth. Expect widespread surface hoar throughout the region, concentrated on northerly aspects. This will be a stability concern when the next storm lands on this very weak layer. The bottom line: Above 7000′, we have a mostly stable snowpack. Wind slabs may still be present on steep leeward terrain, avoid wind-loaded start zones greater than 35º. Isolated pockets of buried surface hoar exist. Warm temps and sun are affecting southern aspects, wet loose avalanches could be an issue. Continue to practice safe travel protocols in case you find an exception to a generally stable snowpack. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Below 7000′, the snow mostly lacks the depth for decent skiing or avalanches. High pressure has weakened the snowpack with faceting and created surface hoar. It will continue to do this through the rest of the week. These layers will be important to take note of as they will affect stability with subsequent snowfall. Please help us track these layers by submitting an observation if you get out in the backcountry. Ski and ride safe The post Avalanche Advisory for December 3, 2020 appeared first on Missoula Avalanche.​

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 05, 2020 06:50 am​ Is this email not displaying correctly? View it in your browser.​

​ ​

​ Avalanche Advisory for December 5, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is MODERATE in upper elevation terrain and LOW elsewhere. Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 5, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. The high pressure is still with us, and it looks like it will be holding on till Wednesday. The inversion has intensified and higher peaks did not freeze last night with temps ranging from 31 º to 38º above 7000′ while the valley bottom was 15º. Winds have been calm with brief gusts. Temperatures up to 50º are forecast for the highest peaks today. The extended above freezing temperatures and strong solar warming be loosening bonds within the snowpack today. Loose wet avalanches are likely and wet slab avalanches are possible. Yesterday, the extent of the surface hoar was not nearly as extensive as we expected. With above freezing temperatures, it did not grow at high elevations last night. As the night time temps dip back below freezing expect surface hoar development but mostly isolated to northern aspects and lower elevations. While it is not a stability issue currently, surface hoar is a persistent weak layer that can cause stability issues for a long time once it is buried. We found near-surface facets in the upper 4″ yesterday in the Rattlesnake, but the lower snowpack was well bonded without failures in stability tests at 7500′ on a northeast aspect. The areas of shallow snowpack such as windswept slopes and below 7000′ are of more concern. These areas are developing facets more extensively and may be a stability issue with further snow load. In the Rattlesnake yesterday wind slab from Monday was well bonded. However, there may still be pockets of reactive wind slabs in steep wind-loaded start zones. The bottom line: Elevated overnight temperatures and solar radiation will be creating wet snow problems. Wet loose avalanches are likely and wet slab is possible. Southern aspects will be most affected. Wind slabs may still be present, practice caution in wind-loaded start zones greater than 35º. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. The avalanche center forecasts for a 1420 square mile area stretching from Lost Trail to Seeley Lake, we can’t see it all weekly. Your snowpack and conditions observations help fill in the gaps and produce a more accurate forecast, please submit them here. Ski and ride safe The post Avalanche Advisory for December 5, 2020 appeared first on Missoula Avalanche.​

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 08, 2020 06:35 am​ Is this email not displaying correctly? View it in your browser.​

​

Avalanche Advisory for December 8, 2020 View Full Advisory » The avalanche danger is LOW in the west central Montana backcountry. The snowpack is generally stable. There may be unstable snow in isolated terrain features. This is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 08, 2020. This advisory 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 Throughout the advisory area, we have been dealing with inversions. Valleys have been cold, and higher elevations have been warmer. This has produced faceted rotten snow at mid-elevation slopes from 6000 ft to 6500 ft. The layers near the ground are currently gaining strength from 6500 ft to 9000 ft. The snowpack is generally stable. Throughout the advisory area, stability tests and red flags support this trend of decreasing avalanche danger. The bottom layers in our snowpack are not reactive in our tests. The primary concern with the next loading events will be pockets of surface hoar in sheltered shady aspects. Once surface hoar is buried, it becomes a persistent weak layer in the snowpack. The other concern will be faceted weak old snow surfaces. Bottom Line West and southwest winds gusting to the high twenties today will help keep the temperatures from producing loose wet avalanche problems. Wednesday, look for the inversions to break and precipitation to enter the forecast area. Changing weather creates changing avalanche conditions. The new snow or rain, depending on the elevations, will be falling on weak old snow surfaces. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Upcoming Education Events: Visit our education page for an up to date list of regional educational events and course offerings. Below are a few select events and opportunities to check out this week.​ Wednesday, December 9, 6–7:30 pm MST, FREE Online 1.5-hr Avalanche Awareness Session. Register Here​ Special Announcements: Due to COVID-19, the West Central Montana Avalanche Foundation could not host our biggest annual fundraiser in person this year. While we look forward to having an in-person event again in the future, the Pray for Snow online auction has arrived. The auction is open now and ends on Tuesday, December 15th at 10 pm MST. All proceeds benefit the West Central Montana Avalanche Center and provide free educational opportunities for all backcountry user groups. Please help us spread the word and show your support by participating HERE The avalanche center forecasts a 1420 square mile area stretching from Lost Trail to Seeley Lake; we can’t see it all weekly. Your snowpack and conditions observations help fill in the gaps and produce a more accurate forecast, and please submit them here. Ski and ride safe. The post Avalanche Advisory for December 8, 2020 appeared first on Missoula Avalanche.​

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 10, 2020 06:22 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 10, 2020 View Full Advisory » The avalanche danger is LOW in the west central Montana backcountry. The snowpack is generally stable. There may be unstable snow in isolated terrain features. This is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 10, 2020. This advisory 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 It is currently 36 degrees F at the Missoula airport this morning. Mountain temperatures range from 30 F at Lolo pass to 19 F at Saddle mountain near Lost Trail pass. Yesterday a short burst of active weather brought a trace to an inch of snow to the advisory area. Snow depths range from 14 inches around 6000 ft to 24 inches at 7500 ft and 50 inches at 8600 ft in the Gash point area in the Bitterroot. This is fairly consistent with what we are finding throughout the forecast area. The snow surfaces are a mixture of firm snow, faceted snow, wind-scoured slopes, and isolated pockets of surface hoar in shady aspects. There are persistent weak layers to investigate and track in the top third of the snowpack above 6500 ft. The first is buried surface hoar in the southern Bitterroot. The other is a layer of facets found near Glen Lake and Gash Point in the Bitterroot. The last layer to look at is weak faceted snow in the bottom third of the snowpack, located near Lost Trail. Overall the snowpack is stable. Dig a pit before committing to any steep slope. Watch for obstacles in areas of thin snowpack. Pay attention to changing weather conditions and how they are affecting avalanche danger. Bottom Line The snowpack is generally stable. Low danger does not mean no avalanche danger. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Special Announcements: Due to COVID-19, the West Central Montana Avalanche Foundation could not host our biggest annual fundraiser in person this year. While we look forward to having an in-person event again in the future, the Pray for Snow online auction has arrived. The auction is open now and ends on Tuesday, December 15th at 10 pm MST. All proceeds benefit the West Central Montana Avalanche Center and provide free educational opportunities for all backcountry user groups. Please help us spread the word and show your support by participating HERE The avalanche center forecasts a 1420 square mile area stretching from Lost Trail to Seeley Lake; we can’t see it all weekly. Your snowpack and conditions observations help fill in the gaps and produce a more accurate forecast. If you get out, please take a minute to fill out the online observation form. Ski and ride safe. The post Avalanche Advisory for December 10, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 12, 2020 06:39 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 12, 2020 View Full Advisory » The avalanche danger is LOW in the west central Montana backcountry. The snowpack is generally stable. There may be unstable snow in isolated terrain features. This is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 12, 2020. This advisory 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 range from 14 degrees F to 24 degrees this morning. 1 to 3 inches of new snow fell in the last 24 hours. Yesterday we found multiple weak layers in our snowpack. None of these layers were reactive in our pit tests. There are two layers of buried surface hoar in the top third of our snowpack. They are not on every aspect. We have found these layers in the southern Bitterroot near Lost Trail pass, in Seeley Lake area, and the central Bitterroot. We have weak faceted crust combinations on other aspects. There is weak faceted snow near the ground. These layers are not a problem now but with more loading, next week are the ones to keep our eyes on. The new snow is not yet enough to tip the scales for our weak layers to be a problem. If you are out and you start to see more than 8 inches of new snow, dial back your terrain and investigate our weak layers in the snowpack. Dig a pit before committing to any steep slope. Watch for obstacles in areas of thin snowpack. Pay attention to changing weather conditions and how they are affecting avalanche danger. Bottom Line The snowpack is generally stable. Low danger does not mean no avalanche danger. There are multitudes of old snow surfaces ,and weak layers varied on aspect and elevation. Take the time when traveling to inventory how the snow is changing when traveling. These will be landmarks for navigating the avalanche danger when we experience a more active weather period in the next week. Normal caution is called for today. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Special Announcements Due to COVID-19, the West Central Montana Avalanche Foundation could not host our biggest annual fundraiser in person this year. While we look forward to having an in-person event again in the future, the Pray for Snow online auction has arrived! The auction is open now and ends on Tuesday, December 15th at 10 pm MST. We will be adding new items throughout the weekend, so remember to check back in. All proceeds benefit the West Central Montana Avalanche Center and provide free educational opportunities for all backcountry user groups. Please help us spread the word and show your support by participating HERE The avalanche center forecasts a 1420 square mile area stretching from Lost Trail to Seeley Lake; we can’t see it all weekly. Your snowpack and conditions observations help fill in the gaps and produce a more accurate forecast. If you get out, please take a minute to fill out the online observation form. Ski and ride safe. The post Avalanche Advisory for December 12, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 15, 2020 06:42 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 15, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is LOW with extra caution in upper elevation wind loaded terrain. Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 15, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. Mountain temperatures are 17º to 26º this morning and highs were around 26º at 7000′ in the past 24 hours. The Snotel sites tell us the mountains received between 0″ and .1″ of snow water equivalent overnight. Tours yesterday revealed 2″ of new snow on the ground at Lolo Pass and Pyramid Peak. The Rattlesnake had slightly more with 3″, and the southern Bitterroot up to 6″. Winds have been mild the past few days, wind transport was minimal but present at higher elevations. 4″-8″ wind slab was touchy at ridge top on east slopes in the Swans yesterday. These could produce very small windslab avalanches less than D1 in size but could be consequential if they carried a rider over a cliff band or into hazards. Lost Trail saw stronger winds Sunday, and there may be larger wind slabs in that area. The two weeks of high pressure haven’t done our snowpack any favors, which has shrunk considerably and developed facets throughout the forecast area. Buried surface hoar is found in multiple locations as well. Despite the very poor structure, the current risk from this snowpack is low. Stability tests are producing inconsistent results and showing low propagation likelihood. However, it is a weak and incohesive base for further snow to land on and will likely be an issue as snow accumulates. Facets are slow to heal, and the problem will be with us for a while. With both snow and moderate winds in the forecast, we will likely see larger wind slabs develop. Whether there will be enough snow to stress existing weak layers and cause deeper failures is yet to be seen. Expect to see the hazard rating increase. The bottom line: The existing snowpack has faceted and lost cohesion but presents a low risk of avalanches currently. Further snow load may stress weak layers to the point of failure. Very small wind slabs are possible at high elevation ridge tops. These will increase in size with snow and wind. Normal caution is called for today. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Special Announcements: Due to COVID-19, the West Central Montana Avalanche Foundation could not host our biggest annual fundraiser in person this year. While we look forward to having an in-person event again in the future, the Pray for Snow online auction is underway and closes today, at 10 PM MST! We will be adding new items throughout the day, so make sure to place your bids accordingly and check back in. All proceeds benefit the West Central Montana Avalanche Center and provide free educational opportunities for all backcountry user groups. Please help us spread the word and show your support by participating HERE The West Central Montana Avalanche Center (WCMAC) generates avalanche forecasts for a 1420 square mile area. The forecast area stretches from Lost Trail Pass to just north of Seeley Lake, Montana. Our team works hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the Missoulaavalanche.org online observation form. Ski and ride safe. The post Avalanche Advisory for December 15, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 17, 2020 06:46 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 17, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is a strong MODERATE. Isolated pockets of higher hazard may exist. Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 17, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. Mountain temperatures are 23º to 32º this morning. The Snotel sites tell us the mountains received between 0.3″ and 0.7″ of snow water equivalent in the past 24 hours. Tours yesterday revealed 4-6″ of new snow on the ground at St. Mary’s, 6″ at Glen lake, 3″ at Sheep Mt, and 2″ in the southern Bitterroot around Lost Trail. There is a broad range of conditions throughout the forecast area, some areas have touchy windslab, some have a reactive surface hoar layer under the new snow, others are still generally stable. Approach all slopes with suspicion and practice extra caution as the mountains receive more snow and wind. Tuesday’s snow came in with moderate winds at upper elevations and there was evidence of considerable wind transport yesterday. Further snow and wind last night have added to the thickness and size of wind slabs. These overlay a variety of surfaces including near surface facets and surface hoar compounding the wind slab problem. Yesterday in the Lost trail backcountry wind slabs at ridge top were remotely triggered and some combination of persistent weak grains likely played a role. Due to the presence of the weak grains wind slabs may remain touchy for longer than normal. All upper elevation, leeward slopes likely have windslab. Buried surface hoar can be found throughout the forecast area. In many places, the overlying slab lacks the cohesion or depth to propagate. However, it was very reactive, failing on isolation on a NE slope at 7300′ on Sheep Mt yesterday and woomfing was experienced. In the Rattlesnake, 6″ of storm snow was failing easily on surface hoar and there were rumors of cracking and shifting snow on Mt. Fuji at Lolo Pass where widespread surface hoar was noted. Lolo Pass received the most snow last night, roughly 7″, bringing the storm total to over 12″ so far, and creating the thickest slab over this problem layer in the forecast area. Practice extra caution if you are riding there today. As more snow accumulates throughout the forecast area this could become a widespread problem. Most areas are also plagued by faceting deep in the snowpack, which has continued to lose cohesiveness. These layers are not yet propagating consistently in stability tests but the structure is very poor. Observations yesterday indicated these facets are continuing to grow. The snowpack on sheep Mt. was considerably more faceted than 2 weeks ago. The snowpack on NW slopes on Pyramid peak is composed entirely of noncohesive facets, reminiscent of our snowpack leading up to the January avalanche cycle last year. The concern is that as snow piles up as a cohesive slab over these weak layers it may trigger a large avalanche cycle. With snow in the forecast throughout the week, high winds, increased temps, and abundant moisture forecast this weekend we may see the avalanche hazard rise sharply. The Bottom Line: Winds have created touchy windslab that will continue to grow with snow and wind today. Avoid wind loaded start zones greater than 30º. A variety of persistent weak layers exist throughout the snowpack which is currently being loaded by new snow. Storm snow failing on buried surface hoar is possible, with more risk in areas that received more snow. The likelihood of avalanches will increase with continued snowfall. As always practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. The current storm cycle coincides with the start of the holidays and we expect to see more people out in the backcountry in the coming week. Please exercise caution. We are coming out of a long stretch of low hazard and no snow, the draw of fresh powder is strong but we may be entering into a very active avalanche cycle. We generate avalanche forecasts for a 1420 square mile area that stretches from Lost Trail Pass to just north of Seeley Lake. We work hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the online observation form. Ski and ride safe The post Avalanche Advisory for December 17, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 19, 2020 06:44 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 19, 2020 View Full Advisory » The avalanche danger in the west central Montana backcountry is CONSIDERABLE. Good morning, this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 19, 2020. This advisory does not apply to operating ski areas, expires at midnight tonight, and is the sole responsibility of the U.S. Forest Service. Mountain temperatures are 24º to 29º this morning. They are forecast to be 24º to 36º today. The mountains received between .4″ and .8″ of snow water equivalent in the past 48 hours. 3-4” of snow are forecast today with up to an additional 14″ by tomorrow night. Winds have been 12 mph to 20 mph, with gusts to 30. Today winds will reach 33 mph, with gusts to 61 mph, and will continue through Sunday night. Rapid loading by wind and snow, as we are forecast to receive in the next 48hr, could trigger a widespread avalanche cycle. The conditions yesterday were similar to two days prior with the addition of 4”-8″ of new snow. This has buried weak layers deeper. Whumfing and cracking are happening more frequently, indicating the snowpack is stressed by the increased load. Buried surface hoar and near surface facets are propagating in stability tests indicating that slab avalanches are possible. Mid elevations, 5000′-7500′, and shallow areas such as wind swept ridges and south faces have the poorest snowpack structure and are the most likely places to trigger an avalanche on these problem layers. Woomfing was reported yesterday at Lolo Pass, Lost Trail, and The Swans. Facets and buried surface hoar are the culprits in these areas. The Rattlesnake had a variety of stability concerns on all aspects, involving the same problem layers. The central Bitterroot, at St. Mary’s, primarily had a storm slab problem that will be more likely to propagate with further loading and consolidation. Wind slab remains a concern on upper elevation leeward slopes. These will grow rapidly today with strong winds and additional snow. Windslab may be deposited lower on slopes due to strong wind transport. In many areas, windslab will be deposited on near surface facets that could increase touchiness and remain unstable for longer than windslab alone. Many areas are also plagued by faceting deep in the snowpack. These layers are not yet propagating consistently in stability tests but the structure is very poor. The snowpack on Pyramid peak is composed entirely of noncohesive facets, reminiscent of our snowpack leading up to the January avalanche cycle last year. Other peaks in the area likely have a similar structure. There is some concern that as snow accumulates, it may overload these faceted layers and cause larger avalanches. The Bottom Line: New snow has continued to load a variety of persistent weak layers. Red flags such as whumfing and shooting cracks have increased, indicating that stability has decreased. The likelihood of avalanches will increase with continued snowfall. Wind slab will build quickly today and become touchy. Avoiding slopes over 30º and enjoying low angle powder is a good plan during the next couple of days. As always, practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. The current storm cycle coincides with the start of the holidays and we expect to see more people out in the backcountry in the coming week. Please exercise caution. We are coming out of a long stretch of low hazard and no snow. The draw of fresh powder is strong but we may be entering into a very active avalanche cycle. We generate avalanche forecasts for a 1420 square mile area that stretches from Lost Trail Pass to just north of Seeley Lake. We work hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the online observation form. Ski and ride safe. The post Avalanche Advisory for December 19, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 20, 2020 07:19 am Is this email not displaying correctly? View it in your browser.

Avalanche Warning for December 20, 2020 View Full Advisory » An avalanche warning has been issued for the southern Mission, southern Swan, Rattlesnake, and southern and central Bitterroot mountains.The avalanche danger for the west central Montana backcountry is HIGH. Human triggered avalanches are certain. The avalanche hazard is increasing with continued snowfall. Travel in avalanche terrain is not recommended. Avalanches may run long distances and avoid runout zones. This avalanche warning is valid for 24 hours. The avalanche warning will either be extended or terminated at 0700 on December 21, 2020. This danger rating does not apply to operating ski areas and is the sole responsibility of the U.S. Forest Service. Weather and Snowpack The atmospheric river is here. Snotels are reporting .5 to .9 inchs of SWE this morning. Winds are in the 20’s gusting into the 50’s. Snowfall and winds are are creating very dangerous avalanche conditions on all slopes today. Travel in avalanche terrain is not recommended today. Avoid traveling under runout zones. There are many weak layers in our snowpack that are being stressed by this loading event. Avalanches can be triggered remotely today on these buried weak layers. Winds are loading ridge lines and cross loading other slopes. Large wind slabs are being created. Bottom Line Travel in avalanche terrain is not recommended today. Avoid runout zones. You can trigger an avalanche remotely today. Snowfall and winds are creating very dangerous avalanche conditions. This warning will be terminated or extended tomorrow at 0700. Ski and ride safe. The post Avalanche Warning for December 20, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 21, 2020 06:50 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 21, 2020 View Full Advisory » An avalanche warning is extended for the southern Mission, southern Swan, Rattlesnake, and southern and central Bitterroot mountains. The avalanche danger for the west central Montana backcountry is HIGH. The avalanche hazard is increasing with continued snowfall. Human triggered avalanches are very likely. Avalanches may run long distances. Travel in avalanche terrain is not recommended. This avalanche warning is valid for 24 hours. The avalanche warning will either be extended or terminated at 0700 on December 22, 2020. This danger rating does not apply to operating ski areas and is the sole responsibility of the U.S. Forest Service. Weather and Snowpack Current temperatures range from 28 to 33 degrees F throughout the advisory area. rising snow levels will introduce rain to dry snowpacks up to 7000 ft. Winds have loaded leeward slopes and will continue to transport snow throughout today. New snow, rain and wind will continue to stress our weak layers in the snowpack. Travel in avalanche terrain is not recommend today. Avoid runout zones and traveling on slopes greater than 30 degrees. The new snow and rain are loading weak layers in our snowpack creating very dangerous avalanche conditions. Leeward slopes are wind loaded and sitting on weak old snow surfaces or a poor snowpack structure. Rain will create wet avalanche problems today. The current storm cycle coincides with the start of the holidays and we expect to see more people out in the backcountry in the coming week. Please exercise caution. The draw of fresh powder is strong but we may be entering into a very active avalanche cycle. Ski and ride safe. The post Avalanche Advisory for December 21, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Avalanche Advisory for December 22, 2020​ View Full Advisory » The Avalanche warning is terminated this morning. The avalanche danger in the west central Montana backcountry is HIGH on leeward slopes and CONSIDERABLE on all other slopes. Good morning; this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 22, 2020. This advisory 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 are dropping this morning as a cold front pushes into the area. Temperatures are 22 to 31 degrees F. Winds were gusty overnight, with a peak gust of 79 mph registered on Mount Sentinel. Winds will continue today to be 20 to 35 mph at ridgetops through the morning. We have gone through a natural avalanche cycle over the last 48 hours. Several natural slides were reported in this cycle in the southern Bitterroot. Loose wet slides were observed near Lolo and the Rattlesnake. Wet slabs were observed in the Rattlesnake. In the southern Bitterroot, many avalanches were reported and broke initially on the buried surface hoar in the upper third of the snowpack and stepped down to weak facets near the ground with the crowns being 3 to 4 feet deep. The slides ran full path into runout zones on the valley floor. Avoid traveling on or below wind loaded slopes today. Winds have created large, very sensitive slabs on leeward terrain. These can be triggered remotely and from far distances depending on what snowpack structure they were deposited on. We have weak layers in our snowpack. As evidenced in the observations from the last couple of days can produce large avalanches. A rider today could very likely trigger these slides from above, below, and from the side today. Avoiding slopes over 30º and not connected to steeper terrain is a way to mitigate this hazard. Enjoying low angle powder is a good plan during the next couple of days. As always, practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe, and stay alert for signs of instability. Dig a pit. Look for red flags. Bottom Line Today is the day to listen to the snowpack and choose simple low angle terrain. Avoid wind loaded slopes. Avoid traveling under runout zones and steeper terrain. Upcoming Education Events: Please visit our education page for an up to date list of regional educational events and course offerings. Below are a few select events and opportunities to check out this week. Wednesday, December 23rd, 6–7:30 pm MST, FREE Online 1.5-hr Avalanche Awareness Session. Register Here Special Announcements: We want to reiterate our most sincere thanks to everyone who participated in the first-ever Pray For Snow online auction. With your help and our gracious sponsors’ support, we succeeded in raising over $10,000 this year! We look forward to turning these funds into the avalanche forecasts and education programs you need to have fun and stay safe this winter. Again, thank you for your continued support. We couldn’t do it without you! We generate avalanche forecasts for a 1,420 square mile area that stretches from Lost Trail Pass to just north of Seeley Lake. We work hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the online observation form. Four people died in avalanches in the western U.S. on Friday and Saturday. We offer their families and friends our condolences for their losses. Ski and ride safe. The post Avalanche Advisory for December 22, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 24, 2020 06:54 am Is this email not displaying correctly? View it in your browser. Avalanche Advisory for December 24, 2020​ View Full Advisory » The avalanche danger in the west central Montana backcountry is considerable. Cautious route finding is needed today. Wind Slabs and weak facets are creating dangerous avalanche conditions. Good morning; this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 24, 2020. This advisory 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 range from 5 degrees to 17 degrees F this morning. No new snow overnight. Winds are 6 mph to 12 mph. The snowpack has weak facets with a large slab on it. This layer is in the bottom third of the snowpack. Yesterday, we got this layer to propagate in pit tests from the Lost Trail backcountry, Gash Point in the central Bitterroot, Lolo Pass ,and the Rattlesnake. The primary avalanche problem today is persistent slabs. Natural slides were reported from Gash point yesterday. Old crowns were visible when the skies cleared yesterday, this is evidence that our snowpack can produce large dangerous slides. Throughout the advisory area, whumphing and collapsing were reported. These are two red flags that our snowpack is unstable. The second avalanche problem is wind drifted snow. We saw active wind loading on slopes yesterday throughout the advisory area. These slopes will be very sensitive human triggers today. Look for pillows and hollow sounding snow slopes to identify this hazard. Bottom Line The buried weak layers are capable of producing large dangerous avalanches. Choose slopes less than 30 degrees that are not connected to steeper terrain. You can trigger an avalanche from below, the side, or from a ridge. You can trigger an avalanche from flat ground if the slope is connected to steep terrain (> 30 degrees). The riding is good on simple low angle slopes. Get the forecast. Carry a shovel beacon and probe. Only have one person on a slope at a time. Public Observations Thank you to everyone who has taken the time to send in a public observation. Please keep sharing what you find and see while out in the backcountry. This is a great resource to glean information about current conditions. Here is the link to Public Observations. We generate avalanche forecasts for a 1,420 square mile area that stretches from Lost Trail Pass to just north of Seeley Lake. We work hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the online observation form. Ski and ride safe. The post Avalanche Advisory for December 24, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 26, 2020 06:07 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 26, 2020​ View Full Advisory » The avalanche danger in the west central Montana backcountry is MODERATE . It is possible to trigger an avalanche on steep slopes today. Good morning; this is Travis Craft with the West Central Montana Avalanche Center’s avalanche advisory for December 26, 2020. This advisory 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 range from 22 to 32 degrees F this morning. A trace to 4 inches of snow has fallen over the advisory area overnight. The snowpack structure is still weak. Facets and crust combinations are still reactive in pit tests. It is still possible to trigger these layers on steep slopes. Winds today will load leeward terrain. Wind slabs are a avalanche problem today. The primary avalanche concern is persistent slabs. The second avalanche problem is wind slabs. Bottom Line Choose low angle slopes today less than 30 degrees. As always, practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe. Remember to re-assess conditions throughout the day and stay alert for signs of instability. Dig a pit. Look for red flags. Public Observations Thank you to everyone who has taken the time to send in a public observation. Please keep sharing what you find and see while out in the backcountry. This is a great resource to glean information about current conditions. Here is the link to Public Observations. We generate avalanche forecasts for a 1,420 square mile area that stretches from Lost Trail Pass to just north of Seeley Lake. We work hard to keep you informed of current avalanche dangers but, we can’t see everything. Your snowpack and weather observations help us fill in the gaps and produce a more accurate forecast. If you get out, please take a moment to fill out the online observation form. Ski and ride safe. The post Avalanche Advisory for December 26, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 29, 2020 06:37 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 29, 2020​ View Full Advisory » The avalanche danger in the west central Montana backcountry is MODERATE. Good morning; this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 29, 2020. This advisory 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 16º F this morning and are forecast to reach the high 20’s today. Clear skies and cold nights have dominated since the last forecast and extensive surface hoar has grown throughout the forecast area. Winds were calm to mild yesterday and will be light with moderate gusts today. Wind slabs are not expected to build in the next 12 hours, but increasing winds tonight will start to transfer snow to leeward slopes. The snowpack is varied throughout the forecast area. Deeper areas have better bonding and are not showing consistent failures in stability tests. Weak layers still exist in isolated areas and avalanches are possible in these zones. In shallow areas, generally under 5 feet in depth, the snowpack structure is still poor. Facets and crust combinations are reactive in pit tests. While the strength is increasing, propagation in tests shows us that slab avalanches are possible. These are becoming a low likelihood high consequence problem as persistent weak layers get buried deeper. Lolo Pass had two concerning faceted layers yesterday, 8” and 31” deep that were propagating in extended column tests. These exist on multiple aspects, and staying on slopes under 33º is wise if you are riding in the Lolo Pass area. A natural avalanche was reported in the Swans yesterday. This area had extensive faceting before Christmas that is likely still lurking and contributed to this slide. Extended column tests on Pyramid Peak were failing on buried facets on the 24th. Investigate the Swan snowpack carefully before committing to steeper slopes. The southern Bitterroots, outside of Lost Trail has also had a shallower, faceted snowpack. Extensive surface hoar has grown throughout the forecast area and will be a problem layer with our next snow load. Bottom Line Careful snowpack assessment is required as persistent weak layers exist in specific areas. Digging a pit, looking for sugary snow layers, and performing stability tests is crucial for making informed decisions. Where persistent grains are present stick to slopes under 33º that are not connected to steeper slopes. Practice safe travel protocols. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe. Remember to re-assess conditions throughout the day and stay alert for signs of instability. Look for red flags. Public Observations Thank you to everyone who has taken the time to send in a public observation. Please keep sharing what you find and see while out in the backcountry. This is a great resource to glean information about current conditions. Here is the link to Public Observations. Ski and ride safe. The post Avalanche Advisory for December 29, 2020 appeared first on Missoula Avalanche.

 

[Scott]

Current West Central Montana Avalanche Advisory Posted: Dec 31, 2020 06:56 am Is this email not displaying correctly? View it in your browser.

Avalanche Advisory for December 31, 2020​ View Full Advisory » The avalanche danger in the west central Montana backcountry is CONSIDERABLE. Human triggered avalanches are likely, especially in wind loaded terrain. Good morning; this is Jeff Carty with the West Central Montana Avalanche Center’s avalanche advisory for December 31, 2020. This advisory 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 18-29º F this morning and are forecast to reach the low 30’s today. 7″ to 14” of snow has fallen in the last 24 hours. 1”-3″ more is expected today. Winds have been moderate with strong gusts and are expected to reach 13mph with gusts to 25mph today. New snow and wind slab are falling on extensive surface hoar and near surface facets that developed during the high pressure over the weekend. These are very weak, slippery layers that will become more reactive with increased load and may slide on lower angle slopes than other problem layers. They have the potential to propagate long distances and the potential size of avalanches will increase with further loading and consolidation. Remotely triggered avalanches are possible. The underlying snowpack is varied throughout the forecast area. Deeper areas have better bonding and instabilities are isolated to the new snow/old snow interface. The central Bitterroot has been the most stable zone in the past week. In shallow areas, generally under 5 feet in depth, the snowpack structure is still poor. Facets and crust combinations are propagating in stability tests. These are becoming a low likelihood high consequence problem as persistent weak layers get buried deeper. However, wind slab or storm slab avalanches may be able to trigger avalanches on these deeper layers. Lolo Pass had two concerning faceted layers Monday, 8” and 31” deep, that are currently being buried deeper. These exist on multiple aspects. A natural avalanche was reported in the Swans Monday. This area had extensive faceting before Christmas and tests on Pyramid Peak were failing on buried facets. This area received the most snow in the past 24 hours and has the highest hazard. The southern Bitterroots, outside of Lost Trail has also had a shallower, faceted snowpack. Bottom Line Extensive surface hoar is being loaded by new snow and wind creating dangerous avalanche conditions. The size and likelihood of potential avalanches will increase throughout the day with further loading. In some areas, storm and wind slab have the potential to trigger deeper avalanches. Stay on slopes under 30º, avoid traveling under avalanche slopes. Travel one at a time in avalanche terrain, carry a beacon, shovel, and probe. Re-assess conditions throughout the day and stay alert for signs of instability. Look for red flags. Public Observations Thank you to everyone who has taken the time to send in a public observation. Please keep sharing what you find and see while out in the backcountry. This is a great resource to glean information about current conditions. Here is the link to Public Observations. Ski and ride safe. The post Avalanche Advisory for December 31, 2020 appeared first on Missoula Avalanche.

 

[christopher]

Weekly snowpack update for the mountains near Cooke City for the weekend of January 1, 2021