Special Avalanche Bulletin – 3/17/2014

The Flathead Avalanche Center (FAC) has issued a Special Avalanche Bulletin for March 17, 2014 to advise backcountry travelers of the elevated avalanche danger. Yesterday we continued with relatively warm weather and light to moderate showers with high snow levels. Overnight a very wet system moved into the area that strongly favored the northern part of the advisory area. In the past 24 hours Flattop Mountain SNOTEL site reported 18 inches of snow with 2.5 inches of snow water equivalent  while Noisy Basin SNOTEL reported only .2 inches of snow water equivalent. Wind speeds have moderated this morning and are currently 5-15 mph with gusts to 25 mph out of the southwest, however  remote weather stations recorded gusts in the 80s overnight. For today, expect increasing west winds, cooling temperatures and lowering snow levels with additional snow accumulation of 10-12 inches. Avalanche hazard will be elevated today in the northern part of the advisory area due to a substantial new snow load and wind transported snow deposited on smooth melt-freeze crusts and previously formed, sensitive wind slabs. Expect to see storm slabs on any aspect with the potential for smaller avalanches to step down into deeper persistent slabs. See yesterday’s advisory below for details on existing avalanche problems. Continue to closely monitor changes in weather conditions and maintain a conservative approach to terrain selection. FAC will be issuing a regularly scheduled advisory on Wednesday, March 19. Check the avalanche advisory for up to date information and hazard ratings.

 

 

 

Avalanche Advisory – 3/16/2014

THIS ADVISORY HAS EXPIRED.

Issued: March 16, 2014 at 7:00 a.m.
Valid Until: 11:59 p.m. of issue date

Good morning! This is Todd Hannan with the Flathead Avalanche Center avalanche advisory for Sunday, March 16, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Wednesday, March 19, 2014.


MOUNTAIN WEATHER

WeatherGraphicThe fickle spring weather has begun. Over the last 24 hours Noisy Basin SNOTEL recorded the most new snow in the area at 2 inches. Winds have been moderate to strong out of the southwest at most locations, however remote weather stations at the ridge tops recorded extreme wind speeds with gusts in the high 70s overnight. Currently, SNOTEL sites and remote weather stations are reading 26 to 37 °F with winds out of the southwest at 15-30 mph and gusts up to 54 mph. For today expect mostly cloudy skies with temperatures potentially reaching the 40s in some mountain locations and winds out of the southwest at 15-30mph. A moist system moves into the area late this afternoon with the potential for rain up to 6000 feet. The passage of a cold front late tonight/early Monday will rapidly lower snow levels and bring increased gusty west winds.


RECENT OBSERVATIONS

RecentObservationsGraphic

Yesterday we traveled to Spider Bowl (Krause Basin) in the Swan Range. Cloud cover kept temperatures cooler than expected and we found 15-20 cm of unconsolidated snow on top of a supportable melt-freeze crust for most of our ascent. When we reached a ridgeline that had been wind affected the new snow had more of a slab characteristic. We observed moderate southwest wind that was drifting snow at the ridge top through out the day (photo 1, 2). On a north aspect we found 26 cm of new snow on top of a melt-freeze crust. Stability tests proved the new snow layer to be unstable, in 2 extended column tests we were able to propagate fractures within the storm snow using easy force. Failures occurred in a layer of soft, weak snow 26 cm deep with more firm, wind transported snow on top (photo). On our descent the warm temperatures began to affect the snow surface and we observed roller balls and small wet sluffs on steep slopes (photo).

 Skiers in the Paola Creek area yesterday had sunny weather and warmer temperatures. They reported wet heavy snow up to 5500 feet and 9 inches of storm snow that failed on top of a melt-freeze crust with easy force in stability tests.

Our snowpits, BNSF Avalanche Safety observations, and other backcountry users throughout the region noted the continued presence of more deeply buried layers that still pose a deep slab threat (observations). These layers are still reactive in stability tests in some locations (video1, video2).

Extended column test propagated fracture on north aspect in Spider Bowl, Swan Range. 3/15/2014

Extended column test propagated fracture on north aspect in Spider Bowl, Swan Range. 3/15/2014


Roller balls while skiing mid -elevation slope. Krause Basin 3/15/2014

Roller balls while skiing mid -elevation slope. Krause Basin 3/15/2014


Wind transporting snow above Wildcat Lake. Spider Bowl, Swan Range 3/15/2014

Wind transporting snow above Wildcat Lake. Spider Bowl, Swan Range 3/15/2014


Wind transporting snow above Wildcat Lake. Spider Bowl, Swan Range 3/15/2014

Wind transporting snow above Wildcat Lake. Spider Bowl, Swan Range 3/15/2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


SNOWPACK DISCUSSION

Avalanche Problem #1

Wind SlabModerate to strong winds in the past 24 hours created sensitive wind slabs. In many areas these slabs formed on top of a melt-freeze crust making them even more sensitive. Cross loading can form slabs on or near exposed terrain features, spur ridges, and gulley walls at mid-elevations. It is wise to avoid wind loaded areas for several days following a wind event to give freshly formed slabs time to gain strength. Though it is easy to spot a wind loaded slope during clear weather, in periods of reduced visibility it may become necessary to look for other clues to identify wind loaded areas such as scoured windward slopes or cornice development. Cornices may also become less stable with the added stress of increased load and warming, give them a wide buffer when traveling above them and avoid travel below.


Avalanche Problem #2

WetAval

With temperatures remaining above freezing today the threat of wet avalanches continues. The warming will have a strong influence on recent snow that sits on top of a smooth melt-freeze crust. We could see loose, wet avalanches as well as wet slab avalanches at higher elevations where recent snow has not yet been subjected to above freezing temperatures. It may be time to turn around or move to a more shaded aspect if you begin to see roller balls, pinwheels, start sinking into wet surface snow, or it begins to rain on the snow. In wet snow conditions avoid steep slopes above terrain traps, cliff areas and long sustained steep pitches. Wet snow conditions can change rapidly.


Avalanche Problem #3

Deep Slab

The deep persistent slab problem still exists and currently manifests itself in a few ways. The late January crust/facet layer is still present, as well as weak, faceted snow near the ground in areas with a shallower snowpack. Stability tests in some locations still show these layers to be a problem. Both of these layers still pose a threat, and more shallow avalanches can step down to these deeper layers causing large destructive avalanches that can propagate long distances. The most recent avalanche cycle is a good reminder of the destructive potential of an avalanche should it break in deeper layers (photos). These layers may be harder to trigger now, but the consequences of an avalanche breaking on these layers is high. Given the uncertainty of these deep slabs, it is best to avoid slopes where these layers exist, particularly in areas where the snowpack is shallower.

 


BOTTOM LINE

For today the avalanche hazard is CONSIDERABLE. This means that human triggered avalanches are likely, particularly on wind loaded slopes steeper than 35° and in areas where above freezing temperatures contribute to wet avalanche hazard. The hazard could rise to HIGH with a rain on snow event in the afternoon, be aware of changing conditions. Deeper instabilities within the snowpack still exist so cautious routefinding and conservative decision making are essential.

Considerable

 


 

Note: The accuracy of the avalanche advisory becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding/skiing spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.


See recent snow profiles as well as snow profiles from the entire season here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Avalanche Advisory – 3/15/2014

THIS ADVISORY HAS EXPIRED.

Issued: March 15, 2014 at 7:00 a.m.
Valid Until: 11:59 p.m. of issue date

Good morning! This is Erich Peitzsch with the Flathead Avalanche Center avalanche advisory for Saturday, March 15, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Sunday, March 16, 2014.


MOUNTAIN WEATHER

WeatherGraphicA quick storm moved through the region yesterday and overnight. This system dropped 6-9 inches of new snow and 0.4 to 1.2 inches of snow water equivalent (SWE) according to remote weather stations and SNOTEL sites. Temperatures began warm, but cooled off overnight into the low to mid 20s F. Winds were out of the southwest during the storm from 20 – 25 mph with gusts over 60 mph. Today, a ridge of high pressure builds back into the region bringing partly to mostly sunny skies. Currently, remote stations report temperatures from 24 to 29°F with winds 5-15 mph gusting to 35 mph. Temperature will rise today to the mid-40s F in some mountain locations. Skies should be partly to mostly cloudy and winds will be 5-15 mph with gusts to 35 mph out of the southwest.


 RECENT OBSERVATIONS

RecentObservationsGraphic

On Thursday we traveled into the Apgar Mountains of Glacier National Park, and into the southern Whitefish Range yesterday. The intense solar warming and well above freezing temps on Thursday caused the snowpack to become moist and cohesionless. We were sinking up to our knees in wet snow by the end of the day at lower elevations. We also observed weak faceted snow at the ground which was reactive in some of our stability tests on sun exposed slopes (photo and profile), and a good reminder that weak snow exists deeper in the snowpack and can still pose a big problem.

On Friday, it was a different story. We scratched our way along the surface crust on most slopes. We went to check out an avalanche in an area known as Chicken Bones southeast of Big Mountain and Whitefish Mountain Resort. This avalanche likely occurred last Sunday during the most recent rain event. There were actually two slides and they were large. The crown depth is 4-6 feet deep and one slide was nearly a quarter mile wide (photo 1, photo 2, photo 3, observation).

Our observations in this area revealed a sun crust on all but the most shaded slopes. Before this sun crust formed the snow surface was wet the days prior and we observed a couple of small, human triggered loose, wet sluffs even on northeast aspects (photo) – a good indication of unstable, wet surface snow. We also observed softer, weaker snow below the new crust that could be a concern with a large load on it.

Our snowpits, BNSF Avalanche Safety observations, and other backcountry users throughout the region noted the continued presence of more deeply buried layers that still pose a deep slab threat (observations). These layers are still reactive in stability tests in some locations (video1, video2).

 

Sidewall from a SE aspect in the Apgar Mountains in Glacier National Park. 3/13/2014.

Sidewall from a SE aspect in the Apgar Mountains. 3/13/2014.


Small wet, loose sluff triggered by turn. On sun exposed slopes, even like this NE aspect, wet loose avalanche are a possibility. 3/14/2014.

Small wet, loose sluff triggered by turn. 3/14/2014.

;

This avalanche likely occurred on Sunday (3/9/2014). They were observed and reported to us on Thursday, and FAC staff investigated the crown in Chicken Bones and determined it did not occur Thursday. Snow on the debris and bed surface indicate it occurred prior to the last snowfall which was Monday (3/10/2014). The crown depth was about 110 to 170 cm (43 - 70 inches). 3/14/2014.

Crown of avalanche in southern Whitefish Range that occurred last weekend. 3/14/2014.

 


 SNOWPACK DISCUSSION

Avalanche Problem #1

Storm Snow

This quick moving storm deposited enough snow that it will become a problem today. Since most of it accumulated from late afternooon through the night, we don’t know how cohesive or “slabby” it is. Regardless, we should expect to encounter a slew of issues with the new snow. Given that it fell on a firm, smooth crust we are likely to see loose sluffs on shaded slopes, wind slabs on leeward slopes, and storm slabs. As the day progresses and warms, the slab will become more cohesive and we could begin to see natural avalanches on sun exposed slopes. As the mercury climbs this new snow will become much more susceptible to human triggering. It is important to pay attention to rapidly changing conditons such as warming above freezing and to which slopes are affected by the sun. It is also essential to be cautious in route-finding and aware of the terrain above you. Avoid terrain traps where even a small slide has high consequences.


Avalanche Problem #2

WetAval

All the right ingredients for wet snow avalanches exist today:
1. New snow
2. Bed surface (crust)
3. Above freezing temps and ample sunshine
The warming will have a strong influence on this new snow. We should see loose, wet avalanches today that will follow the compass around from northeast to west slopes through the day. It may be time to turn around or move to a more shaded aspect if you begin to see roller balls, pinwheels, or start sinking into wet surface snow. Avoid steep, sunlit slopes above terrain traps, cliffs areas and long sustained steep pitches. Wet snow conditions can change rapidly. Cornice failure this time of year is also a concern. Give cornices a wide berth and avoid traveling beneath them. Breaking cornices have the potential to trigger avalanches in deeper layers.


Avalanche Problem #3

Deep Slab

The deep persistent slab problem still exists and currently manifests itself in a few ways. The late January crust/facet layer is still present, as well as weak, faceted snow near the ground in areas with a shallower snowpack. Stability tests in some locations still show these layers to be a problem. Both of these layers still pose a threat, and more shallow avalanches can step down to these deeper layers causing large destructive avalanches. The most recent avalanche cycle is a good reminder of the destructive potential of an avalanche should it break in deeper layers (photos). These layers may be harder to trigger now, but the consequences of an avalanche breaking on these layers is high. Given the uncertainty of these deep slabs, it is best to avoid slopes where these layers exist, particularly in areas where the snowpack is shallower.

 


BOTTOM LINE

With new snow on top of a good sliding surface combined with ample solar warming and above freezing temperatures today, the avalanche hazard is CONSIDERABLE and could rise to HIGH on sun exposed slopes 35 degrees and steeper. This means that human triggered avalanches are likely and natural avalanches are possible to likely given the wet snow hazard. Deeper instabilities within the snowpack still exist so cautious routefinding and conservative decision making are essential.

Considerable

 


 

Note: The accuracy of the avalanche advisory becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding/skiing spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.


See recent snow profiles as well as snow profiles from the entire season here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Avalanche Advisory – 3/12/2014

THIS ADVISORY HAS EXPIRED.

Issued: March 12, 2014 at 7:00 a.m.
Valid Until: 11:59 p.m. of issue date

Good morning! This is Todd Hannan with the Flathead Avalanche Center avalanche advisory for Wednesday, March 12, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Saturday, March 15, 2014.


MOUNTAIN WEATHER

WeatherGraphicAfter a week of very wet conditions a ridge of high pressure built over the area yesterday. We began to dry out with relatively warm daytime temperatures and light winds over most of the area. Currently temperatures are 21-29°F(SNOTEL) and winds are 2-10 mph with gusts to 27 mph out of the southwest (remote weather stations). The higher ridge tops are still experiencing strong winds, Snowslip mountain remote weather station is reporting wind speeds of 28 mph with gusts in the 40s. Today the high pressure ridge remains parked over us, bringing clear skies and another relatively warm day. Winds will be light (5-10mph) out of the southwest. Another round of precipitation expected to impact the area on Friday.


 

RECENT OBSERVATIONS

RecentObservationsGraphicYesterday we rode into Canyon Creek in the Whitefish Range to investigate an avalanche that was reported on Sunday in an area known as Skook Chutes. The debris piles had been groomed over but were still impressive(photo1, 2). We did a crown profile in a lower area that the avalanche propagated in to and found that the avalanche failed on top of a hard melt-freeze crust within a layer of less consolidated and slightly drier snow than the overlying slab. The average crown height was 70 cm in our location but another crown above appeared to be much deeper, potentially involving a step down into persistent slab. While riding in we observed several loose, wet avalanches that had recently occurred on solar aspects. We rode to Kimmerly Basin and skied up to the ridge. We found 20cm of low density new snow on top of a supportable melt freeze crust with small (1-2mm) surface hoar forming. Stability tests in a pit dug on a northeast aspect revealed a layer of graupel that was 1.5 feet down that was able to propagate a fracture using hard force in an extended column test.

 BNSF avalanche safety was in John F. Stevens Canyon yesterday and reported surface snow that was heavy and wet due to warm temperatures and solar influence. They also noted continued concern associated with persistent slab (Observation).

Wet loose activity in Canyon Creek. 3/11/2014

Wet loose activity in Canyon Creek. 3/11/2014


Debris from avalanche in Skook Chutes  that occurred Sunday morning (3/9). Canyon Creek 3/11/2014

Debris from avalanche in Skook Chutes that occurred Sunday morning (3/9).
Canyon Creek 3/11/2014


Debris from avalanche in Skook Chutes  that occurred Sunday morning (3/9). Canyon Creek 3/11/2014

Debris from avalanche in Skook Chutes that occurred Sunday morning (3/9).
Canyon Creek 3/11/2014


Additional 20 cm of snow that fell since Sunday on hard bed surface of avalanche. Canyon Creek 3/11/2014

Additional 20 cm of snow that fell since Sunday on hard bed surface of avalanche. Canyon Creek 3/11/2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

  

SNOWPACK DISCUSSION

Avalanche Problem #1

WetAvalWarm temperatures and more intense solar radiation are expected today. Higher elevations that have not yet been exposed to sharp rises in temperature could begin to be affected by the sun. There will be increased potential for loose wet avalanches within recent unconsolidated snow as well as the potential for wet slab avalanches. Also, keep in mind that recently formed cornices may become more sensitive with warmer temperatures, continue to give them a wide safety margin when traveling above them and avoid travel below. Managing wet snow avalanches ranges from fairly straightforward with loose, wet avalanches to nearly unmanageable with wet slabs. Pay attention to the clues that warming temperatures are making the snowpack unstable like snow surface becoming wet, skis or boots penetrate deeper into the snow, or pin wheels start to roll.

 

 


Avalanche Problem #2

Persistent SlabThe persistent slab on top of the mid-January crust with weak snow above the crust can still pose a threat. Additionally, there is weak snow near the ground in shallow areas that has been recently observed. Once initiated, a persistent slab has the ability to propagate long distances, change aspects, and wrap around terrain features as we witnessed with this past large natural cycle. The potential for smaller avalanches to step down into these deeper layers also still exists. It is important to identify and avoid areas where it is more likely to trigger these deeper slabs, such as steep convex rollovers and in areas with shallow snow often found in steep rocky terrain or scoured areas. Without the obvious signs of instability such as shooting cracks and collapsing the only way to know what you are skiing or riding over is to dig into the snow.

 


BOTTOM LINE

For today the avalanche hazard is rated as CONSIDERABLE on sun exposed slopes and MODERATE on other terrain. This means that natural avalanches are possible and human triggered avalanches are likely on aspects that are exposed to more intense solar warming. Human triggered avalanches remain possible on other terrain, particularly in areas with a relatively shallow snowpack or steep convex rollovers. 

Considerable

 

 

Moderate 

 

 

Note: The accuracy of the avalanche advisory becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding/skiing spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.


See recent snow profiles as well as snow profiles from the entire season here.

Join us March 14, 8:00 p.m. at Penco. We are working with the Flathead Snowmobile Association for the first in a series of motorized specific backcountry safety seminars. Details here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Special Avalanche Bulletin – 3/10/2014

The Flathead Avalanche Center (FAC) has issued a Special Avalanche Bulletin for March 10-11, 2014 to advise backcountry travelers of the elevated avalanche danger. The Flathead Avalanche Center advisory area was under an Avalanche Warning yesterday and for the majority of last week with the Hazard Rating at HIGH, meaning natural avalanches are likely and human triggered avalanches are very likely.  We have both observed and received reports of widespread natural avalanche activity over the the past week. Yesterday BNSF avalanche safety reported wet slab activity in the John F Stevens Canyon there was also a report of a natural avalanche in Canyon Creek. Though the warning has been allowed to expire for today (3/10), the hazard is still elevated as is the potential for natural and human triggered avalanches. See yesterday’s advisory below for details. Continue to closely monitor changes in weather conditions, particularly rain occurring on snow.  Light to moderate precipitation with lowering snow levels is expected to increase later in the morning becoming heavy at times. Snow should taper as a ridge of high pressure builds over the area Tuesday morning. FAC will be issuing a regularly scheduled advisory on Wednesday, March 12. Check the avalanche advisory for up to date information and hazard ratings.

FAC would like to thank all of the individuals and groups that are submitting observations to the avalanche center and assisting to get the message out about elevated avalanche hazard.

 

Avalanche Advisory – 3/9/2014

THIS ADVISORY HAS EXPIRED

Issued March 9, 2014

The Flathead Avalanche Center is issuing a Backcountry Avalanche Warning for the entire advisory area including the Whitefish Range, Swan Range, Flathead Range, and portions of Glacier National ParkRising temperatures and continued rain have created highly unstable conditions. Natural and human triggered avalanches are likely.The avalanche danger is still rated HIGH on all slopes in our advisory area. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended and avalanche runout zones should be avoided.

This warning will either be allowed to expire or updated by 7:00 a.m. on Monday, March 10.

Issued: March 9, 2014 at 7:00 a.m.
Valid Until: 11:59 p.m. of issue date

Good morning! This is Erich Peitzsch with the Flathead Avalanche Center avalanche advisory for Sunday, March 9, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Wednesday, March 12, 2014.


MOUNTAIN WEATHER

WeatherGraphicA plume of moist air with subtropical origins is currently impacting the advisory area. This system will cause snow levels to rise to potentially 7000 feet. We can’t catch a break here. Only one sunny, dry day? C’mon. Currently, mountain temperatures range from 32-37 ° F and winds are out of the southwest at 10-30 mph with gusts to 60 mph. Remote weather stations and SNOTEL sites report up to 0.7 inches of precipitation since last night already. Today, temperatures will continue to rise through the day potentially reaching into the 40s F at 6000 feet. Precipitation will continue through the day with the most intense rates occurring in the morning. As of 6:00 a.m. this morning, it appears we have yet to see the bulk of moisture move through the area. We could see over an inch (or more) of rain in the mountains during this time. Winds will remain out of the southwest at 15-25 mph with gusts to 40-50 mph.


 

RECENT OBSERVATIONS

RecentObservationsGraphic

A beautiful sunny, mild day yesterday was just a tease as conditions have changed rapidly overnight and will continue through at least today. Yesterday, in the Essex area of the northern Flathead Range, we found avalanche carnage in many places. Evidence of large, destructive slides from last week’s natural avalanche cycle is truly impressive (photos and here).

We found north facing aspects above 6000 feet to hold dry snow and sunny aspects became affected by the sun yesterday causing a wet snow surface. Most slopes below this elevation contained wet, heavy snow. There are a couple of layers of concern within the top 2-3 feet of the snowpack like graupel and the new/old snow interface (photo). Moderate to strong southwest winds yesterday were reloading many slopes that had avalanched last week providing a new slab (video) and wind slab at upper elevations. The rain on snow event today will indeed cause stress to the snowpack and we could see large avalanches again. 

We found a shallow snowpack on a southeast aspect yesterday (total snow depth 5 feet) (photo). We dug just below the crown of a large slide. This large slide failed on the late January/early February crust/facet layer. About 8-12 inches of new/wind transported snow now sits on top of this crust. We also found weak snow near the ground in this shallow rocky area and this layer showed signs of instability in our stability tests (video).

BNSF avalanche safety reported two new small natural slabs yesterday in John F. Stevens Canyon in southern Glacier Park during an aerial reconnaissance of the area. Skiers in the Whitefish Range yesterday found similar results in the recent storm snow on northerly aspects and observed the late January crust/facet layer about 5 feet from the surface. (observation).

We received great images from the Swan Range, southern Glacier Park, and the Skyland area (Flathead Range) of the aftermath of the large natural avalanche cycle from this past week. We appreciate folks contributing these images. We will post these today on our Photos page. Today is a great day to avoid the backcountry given the rain and check out these images.

Generalized snow profile in northern Flathead Range. 3/8/2014.

Generalized snow profile in northern Flathead Range. 3/8/2014.

Wind transport of new snow is reloading many slopes. 3/8/2014.

Wind transport of new snow is reloading many slopes. 3/8/2014.

Crown of a large natural avalanche on Peak 7798 at the head of Marion Lake, Flathead Range. 3/8/2014.

Crown of a large natural avalanche on Peak 7798 at the head of Marion Lake, Flathead Range. 3/8/2014.

 

 

 

 

 

 

 

 

 


 

 SNOWPACK DISCUSSION

Avalanche Problem #1

Storm SnowThe new load/stress this rain and snow at the very upper elevations will place on the snowpack will be enough to cause potentially big problems. We saw the effects of the huge load from rain on snow last week, and we could see the same again today given the intense precipitation rates and amounts. This precipitation could cause slopes that already avalanched to slide again given the reload many of these slopes experienced. It is best to avoid avalanche terrain today including runout zones of avalanche paths.

 


Avalanche Problem #2

WetAvalRain on snow is likely to cause wet snow problems particularly at lower elevations. The snow surface below 6000 feet is already wet from last week’s rain and yesterday’s warming . Wet loose avalanches are likely as well as wet slabs given the intense rain forecasted. Wet slabs can be very destructive. The avalanches from last week started dry, entrained wet snow at lower elevations, and gouged many gullies and slopes due to the pure mass of wet snow debris. Managing wet snow avalanches ranges from fairly straightforward with loose, wet avalanches to nearly unmanageable with wet slabs. Avoiding avalanche terrain today is recommended due to the rain on snow event.

 


Avalanche Problem #3

Deep Slab

The persistent slab on top of the mid-January crust with weak snow above the crust can still pose a threat. Additionally, there is weak snow near the ground in shallow areas as we observed yesterday. Once initiated, a persistent slab has the ability to propagate long distances, change aspects, and wrap around terrain features as we witnessed with this past large natural cycle. Rain on snow will place additional stress to these layers so we could see these persistent slabs rear their ugly heads again today. The potential for smaller avalanches to step down into these deeper layers also still exists. It is important to identify and avoid areas where it is more likely to trigger these deeper slabs, such as steep convex rollovers and in areas with shallow snow often found in steep rocky terrain or scoured areas. Without the obvious signs of instability such as shooting cracks and collapsing the only way to know what you are skiing or riding over is to dig into the snow.

 


BOTTOM LINE

The avalanche hazard depends a lot on the weather today. With continuing intense precipitation rates and rain to potentially 7000 feet the avalanche hazard is HIGH. This means that natural avalanches are likely and human triggered avalanches are very likely. Wet avalanches will become a problem with rising temperatures and rain, and we could see yet another widespread, large natural avalanche cycle. Travel in avalanche terrain is not recommended today.

 

 

 

Note: The accuracy of the avalanche advisory becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding/skiing spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.


See recent snow profiles as well as snow profiles from the entire season here.

Join us March 14, 8:00 p.m. at Penco. We are working with the Flathead Snowmobile Association for the first in a series of motorized specific backcountry safety seminars. Details here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Avalanche Advisory – 3/8/2014

THIS ADVISORY HAS EXPIRED

Issued: March 8, 2014 at 7:00 a.m.
Valid Until: 11:59 p.m. of issue date

Good morning! This is Erich Peitzsch with the Flathead Avalanche Center avalanche advisory for Saturday, March 8, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Sunday, March 9, 2014.


MOUNTAIN WEATHER

WeatherGraphicWell, it seems like someone finally turned off the faucet…for today at least. Storm totals were impressive since Sunday (see below). A brief break in stormy weather occurs today as a short-lived ridge exists over the region. Currently, mountain temperatures range from 25-33° F and winds are out of the west-southwest at 5-17 mph. Today, temperatures will climb above freezing in many locations potentially into the mid-40s F. Intense solar warming is expected as long as the cloud cover stays away. Wind will be out of the southwest at 10-20 mph with gusts to 40 mph. Another moist system will roll through the area tonight and tomorrow with rising temperatures and the potential of snow levels rising to 7000 feet.

 


 

RECENT OBSERVATIONS

RecentObservationsGraphic

Snow accumulation from this past storm ranged from 15-30 inches, but the amount of weight placed on the existing snowpack is measured in snow water equivalent. True total snowfall amounts are difficult to assess from SNOTEL sites from this storm because of such warm temps, rain, and rapid settlement rates. Here are snow water equivalent (SWE) storm totals from area SNOTEL sites since the onset of the storm on Sunday, 3/2:
Flattop SNOTEL (Glacier Park): 6.5 inches of SWE.
Stahl Peak (Whitefish Range): 4.1 inches of SWE.
Noisy Basin (Swan Range): 3.6 inches of SWE.
Pike Creek (eastern edge of Flathead Range): 3.3 inches of SWE.

A widespread natural avalanche cycle began on Monday (3/3) with moderately sized natural avalanches and continued through Thursday morning with large natural avalanches occurring in all mountain ranges in our advisory area on all aspects (photos and observation). We ventured into the Lost Johnny drainage in the Swan Range on Thursday and observed debris from large, natural avalanches that occurred within the past few days.

On our way to China Basin in the Whitefish Range yesterday, we observed more large avalanches in the Apgar Range along the North Fork of the Flathead River corridor. In China Basin, we observed a heavy, wet snow surface up to about 6000 feet making riding conditions difficult. Above this, the storm snow was still heavy but not quite as wet. We found about 30 inches (80 cm) of new storm snow above an old ice crust. A layer of graupel about 14 inches from the snow surface is a concern (photo). This layer has the potential to propagate a fracture in stability tests (video and snow profile) and is susceptible to human triggering today. The old crust/facet combination from late January/early February is now deeply buried, but was potentially the failure layer of many of the natural avalanches from this past week and cannot be ruled out as a deep persistent slab problem.

We received no other field observations aside from BNSF Avalanche Safety avalanche observations and our own, so our confidence regarding snowpack stability post-storm right now is fair.

Generalized Snow Profile from China Basin in the Whitefish Range. 3/7/2014.

Generalized Snow Profile from China Basin in the Whitefish Range. 3/7/2014.

 

Natural avalanche in the Apgar Range and the North Fork of the Flathead River. 3/7/2014.

Natural avalanche in the Apgar Range and the North Fork of the Flathead River. 3/7/2014.

 

Crown (located just below the thick trees near the top of the slope), Bed Surface, and Debris from a large, natural avalanche (D3/R5) in the Lost Johnny drainage of the Swan Range. 3/6/2014.

A large, natural avalanche (D3/R5) in the Lost Johnny drainage of the Swan Range. 3/6/2014.

 

 

 

 

 

 

 

 

 

  

 


 

 SNOWPACK DISCUSSION

Avalanche Problem #1

Storm SnowEven though precipitation finally tapered and ended yesterday, storm snow is still an avalanche problem. The layer of graupel about a foot or more from the surface shows signs of instability. Typically, graupel is a short-lived instability, but it could be a problem today. Since Sunday, large loads were placed upon the snowpack, and in many locations it failed in a big way. However, there are slopes that did not avalanche and may be waiting for just the right trigger. The snowpack still needs time to adjust to this new load, and above freezing temperatures and solar warming today could exacerbate this problem and natural avalanches are a possibility today. Thus, it is important to ease into the backcountry today and carefully assess each slope. Conservative decision making and careful terrain selection will be essential in determining how reactive the new snow is to human triggering especially with warming well above freezing and intense solar input.

 


Avalanche Problem #2

WetAvalAbove freezing temperatures and intense solar input today are likely to cause wet snow problems. The snow surface is already wet from rain and is likely to become more wet today. Wet loose avalanches are likely on sunny aspects today. Avoiding sun affected slopes, particularly later in the day, will be a good idea. These types of avalanches can entrain a lot of snow especially the new surface snow. Pay attention to rapidly changing conditions and watch for signs of wet snow instability like rollerballs and point releases. 

 


Avalanche Problem #3

Deep Slab

This new storm buried persistent weak layers even deeper. The persistent slab on top of the mid-January crust with weak snow above the crust was a problem before this storm and can still pose a threat. Additionally, there is another layer of weak faceted snow now about 3-4 feet from the surface. Once initiated, a persistent slab has the ability to propagate long distances, change aspects, and wrap around terrain features as we witnessed with this large natural cycle. Remain vigilant in assessing slopes for persistent slab instabilities and be aware of the potential for smaller avalanches to step down into these deeper layers. Identifying deep persistent slabs is only half of the battle. Think of how and in what areas you might be able to trigger them. Continue to avoid areas where triggering these deeper slabs is more likely, such as steep convex rollovers and in areas with shallow snow often found in steep rocky terrain or scoured areas. Without the obvious signs of instability such as shooting cracks and collapsing the only way to know what you are skiing or riding over is to dig into the snow.

 


BOTTOM LINE

For today the avalanche hazard is CONSIDERABLE but could rise higher on sunny aspects with well above freezing temperatures and intense solar warming. This means that human triggered avalanches are likely and natural avalanches are possible today. The new snow still shows signs of instability and the potential of storm slab avalanches exists. Wet avalanches may also become a problem throughout the day with rising temperatures and intense solar warming. Pay attention to rapidly changing conditions and stay off of and out from under slopes affected by the sun later today. Careful snowpack evaluation and cautious route-finding are essential.

Considerable

 

 

 

Note: The accuracy of the avalanche advisory becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding/skiing spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.


See recent snow profiles as well as snow profiles from the entire season here.

Join us March 14, 8:00 p.m. at Penco. We are working with the Flathead Snowmobile Association for the first in a series of motorized specific backcountry safety seminars. Details here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Special Avalanche Bulletin – 3/7/2014

The Flathead Avalanche Center (FAC) has issued a Special Avalanche Bulletin for March 7, 2014 to advise backcountry travelers of the elevated avalanche danger through out the day. The Flathead Avalanche Center advisory area has been under an Avalanche Warning since Monday with the Hazard Rating at HIGH, meaning natural avalanches are likely and human triggered avalanches are very likely. We have both observed and received many reports of large natural avalanches in the past several days. Though the warning has been allowed to expire for today (3/7), the hazard is still elevated as is the potential for human triggered avalanches. See yesterday’s special advisory for details. Light to moderate precipitation with slightly lower snow levels is expected to continue through midday, then taper as a ridge of high pressure builds over the area.  FAC will be issuing regularly scheduled advisories on Saturday and Sunday. Check the avalanche advisory for up to date information and hazard ratings.

FAC would like to thank all of the individuals and groups that are submitting observations to the avalanche center and assisting to get the message out about elevated avalanche hazard.

 

Special Avalanche Advisory – 3/6/2014

THIS ADVISORY HAS EXPIRED

ISSUED ON March 6 2014 at 7:00 am.

The Flathead Avalanche Center is issuing a Backcountry Avalanche Warning for the entire advisory area including the Whitefish Range, Swan Range, Flathead Range, and portions of Glacier National Park.  Continued snow, rising temperatures and snow levels, and strong winds have created highly unstable conditions. Natural and human triggered avalanches are likely.The avalanche danger is rated HIGH on all slopes in our advisory area. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended and avalanche runout zones should be avoided.

This warning will either be allowed to expire or updated by 7:00 a.m. on Friday, March 7.

Good morning! This is Todd Hannan with the Flathead Avalanche Center avalanche advisory for Thursday, March 6, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Saturday, March 8, 2014.


MOUNTAIN WEATHER

WeatherGraphicIn the past 24 hours we received an additional .9-1.7 inches of snow water equivalent with snowfall amounts ranging from 5-9 inches of heavy snow. Currently temperatures are 30- 36°F and winds range from 5mph up to 25 mph out of the southwest. For today expect light snow showers to taper this morning with renewed intensity late afternoon/early evening. Snow levels should remain fairly high, we could continue to see rain up to 5000 feet today, winds will be out of the southwest 10-25 mph with stronger gusts on the ridge tops.

 


RECENT OBSERVATIONS

RecentObservationsGraphicThis is a storm where snow accumulation may not be as impressive as the amount of snow water equivalent (SWE). SWE of new snow is basically the weight added to the existing snowpack, and the mountains picked up a lot! Here is a summary:

 Storm Totals: Since Sun. 3/2 at 4:00 a.m.
Shed 7 (John F. Stevens Canyon): 23”
Noisy Basin (Swan Range): 2.9” SWE, 13” snow
Flattop Mt. (Glacier Park): 5.1” SWE, 26” snow
Stahl Pk. (Whitefish Range): 3.9” SWE, 21” snow
Pike Creek (Flathead Range): 3.3” SWE, 23” snow

BNSF avalanche safety reported substantial natural avalanche activity in their program area overnight, with sizes up to 3.5 out of 5 on the destructive scale. The 3.5 on the destructive scale signifies that it is on the high end of the 3 class where an avalanche could bury and destroy a car, damage a truck, destroy a wood frame house, or break a few trees (Snow, Weather, and Avalanches (3.6.5 Size)).

 

 


SNOWPACK DISCUSSION

Avalanche Problem #1

Storm SnowOver the past few days we have seen a substantial amount of weight added to the snowpack. Short lulls in precipitation have not been sufficient to allow for adjustment to the load. Since the onset of the storm on Sunday, temperatures have warmed, piling heavier more dense snow on top of colder lower density snow. In addition to new snow that recently fell, there have been winds capable of transporting snow and loading leeward slopes with an even heavier burden. The snowpack is providing us with obvious signs of instability such as natural avalanche activity, shooting cracks, and collapsing. It is recommended to heed its warning and avoid avalanche terrain and run outs today.

 

 

 


Avalanche Problem #2

WetAvalGiven the relatively high snow levels today and potential for continued rain at high elevations, wet avalanches are a concern. We saw loose, wet avalanche activity Tuesday and more was reported yesterday. The wide scale collapsing we experienced at low elevations on Tuesday demonstrates the potential for wet slab activity to occur. We could also begin to see renewed activity from glide cracks. At low elevations on roads or trails remember that even small avalanche paths and cut banks can produce dangerous avalanches. Avoid steep slopes and terrain traps such as gullies and narrow canyons when surface snow becomes wet, you observe pin wheels, or it is raining on the snow.

 


Avalanche Problem #3

Persistent SlabPersistent slab remains a concern, particularly as we stress them with a new load. The deep persistent slab on the mid-January crust with weak snow adjacent to the crust still poses a threat in many areas. Additionally, there have been several recent observations of layers of weak faceted snow buried 2-3 feet down from the surface. Once initiated, a persistent slab has the ability to propagate long distances, change aspects, and wrap around terrain features. Remain vigilant in assessing slopes for persistent slab instabilities and be aware of the potential for smaller avalanches to step down into these deeper layers and propagate longer distances. Identifying persistent slab is only half of the battle, be thinking of how and in what areas you might be able to trigger them. Continue to avoid areas where triggering these deeper slabs is more likely, such as steep convex rollovers and in areas with shallow snow often found in steep rocky terrain or scoured areas.

 

 

 

 


BOTTOM LINE

For today the avalanche hazard is rated HIGH. Continued precipitation with rising snow levels and temperatures, will cause very unstable conditions. This means that natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended.

 

High

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: Once again, given this persistent slab problem, we need data/information. The accuracy of the avalanche advisory and our understanding of this persistent slab problem becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.

 


Community Avalanche Awareness Night!!! Join the new Friends of the Flathead Avalanche Center (FOFAC) for avalanche discussions followed by an opportunity to socialize with other winter backcountry enthusiasts.
March 6, 2014 (Thursday). 6:30 pm – 8:00 pm program and social afterwards. Moose Lodge, Whitefish. Details here.

New blog post by Ted Steiner about risk assessment in the backcountry here.

See recent snow profiles as well as snow profiles from the entire season here.

Join us March 14, 8:00 p.m. at Penco. We are working with the Flathead Snowmobile Association for the first in a series of motorized specific backcountry safety seminars. Details here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


Observations are extremely valuable to us. If you’ve been out in the backcountry, please drop us a line with your observations at fac.admin@flatheadavalanche.org or call 406.261.9873. Thanks!


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

 

 

Avalanche Advisory – 3/5/2014

ISSUED ON March 5 2014 at 7:00 am.

The Flathead Avalanche Center is issuing a Backcountry Avalanche Warning for the entire advisory area including the Whitefish Range, Swan Range, Flathead Range, and portions of Glacier National Park. New snow, rising temperatures and snow levels, and strong winds have created highly unstable conditions. Natural and human triggered avalanches are likely.The avalanche danger is rated HIGH on all slopes in our advisory area. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended and avalanche runout zones should be avoided.

This warning will either be allowed to expire or updated by 7:00 a.m. on Wednesday, March 5.

Good morning! This is Todd Hannan with the Flathead Avalanche Center avalanche advisory for Wednesday, March 5, 2014. This advisory applies only to backcountry areas outside established ski area boundaries. The next scheduled advisory will be Saturday, March 8, 2014.


MOUNTAIN WEATHER

WeatherGraphicIn the past 24 we received an additional .3-1.4 inches of snow water equivalent. Snowfall amounts are only 2-7 inches. The snowfall measurements can be deceiving as snow has become increasingly heavy since the onset of the storm and settles underlying lower density snow as it falls. Currently temperatures are 27- 34°F and winds range from 5mph up to 25 mph out of the southwest. For today expect light snow showers this morning increasing midday and becoming heavy at times. Snow levels should continue to rise, we could see rain up to 5000 feet today. Southwest winds are expected to increase late morning to 10-25 mph.

 


RECENT OBSERVATIONS

RecentObservationsGraphicYesterday were in the Cascade/Rescue Creek drainages in the Flathead Range. On our ascent we noted that the top 2-3 inches of snow was affected by the rise in temperature and had become moist. The moist snow surface was present to about 5000 feet then transitioned to a dry graupel surface. While ascending the ridge we noticed that the top 6 inches of snow was denser than underlying snow and cracked around our skis when traveling over it. The light was flat and visibility was not great, but we were able to see debris and evidence of recent avalanche activity in the lower paths and run outs in the Rescue drainage. Extended column tests revealed 2 layers that were capable of propagating a fracture. One failure occurred with moderate force on a density change within recent storm snow 1.5 feet down (ECTP 13) and the other propagated with hard force in lower density snow on top of a melt-freeze crust 2 feet down (ECTP21 and 23) (photo). On our decent we experienced a collapse and long shooting cracks on a low angle slope. At 4400 feet, light snow was transitioning to a rain/snow mix and became all rain just below that. Large pinwheels were forming from snow coming off of our skis onto steeper slopes below (photo). On open slopes these pinwheels triggered loose, wet avalanches. The wet snow was confined to the top 2-3 inches of the snowpack and snow remained dry below that (photo). We experienced several more audible collapses in the snowpack at low elevations, proving that the underlying low density snow was struggling to support the load above.

General storm snow profile. Rescue Creek 3/4/2014

General storm snow profile. Rescue Creek 3/4/2014

Light rain began in the afternoon below 4400 feet. Dry low density snow will have difficulty supporting wet snow above. Cascade Creek 3/5/2014

Light rain began in the afternoon below 4400 feet. Dry low density snow will have difficulty supporting wet snow above. Cascade Creek 3/5/2014

Pinwheels starting to form from snow off of our skis. Cascade Creek 3/4/2014

Pinwheels starting to form from snow off of our skis. Cascade Creek 3/4/2014

 

 

 

 

 

 

 

 

 


SNOWPACK DISCUSSION

Avalanche Problem #1

Storm SnowOver the past few days we have seen a substantial amount of weight added to the snowpack. Short lulls in precipitation have not been sufficient to allow for adjustment to the load. Since the onset of the storm on Sunday, temperatures have warmed, piling heavier more dense snow on top of colder lower density snow. In addition to new snow that recently fell, there have been winds capable of transporting snow and loading leeward slopes with an even heavier burden. The snowpack is providing us with obvious signs of instability such as natural avalanche activity, shooting cracks, and collapsing. It is recommended to heed its warning and avoid avalanche terrain and run outs today.

 

 

 


Avalanche Problem #2

WetAvalGiven the rising snow levels today and increased potential for rain at even higher elevations, wet avalanches are a concern. We saw loose, wet avalanche activity yesterday and the potential will increase today. The collapsing we experienced at low elevation proves the potential for wet slab activity to occur. We could also begin to see renewed activity from glide cracks. At low elevations on roads or trails remember that even small avalanche paths and cut banks can produce dangerous avalanches. Avoid steep slopes and terrain traps such as gullies and narrow canyons when surface snow becomes wet, you observe pin wheels, or it is raining on the snow.

 


Avalanche Problem #3

Persistent SlabPersistent slab remains a concern, particularly as we stress them with a new load. The deep persistent slab on the mid-January crust with weak snow adjacent to the crust still poses a threat in many areas. Additionally, there have been several recent observations of layers of weak faceted snow buried 2-3 feet down from the surface. Once initiated, a persistent slab has the ability to propagate long distances, change aspects, and wrap around terrain features. Remain vigilant in assessing slopes for persistent slab instabilities and be aware of the potential for smaller avalanches to step down into these deeper layers and propagate longer distances. Identifying persistent slab is only half of the battle, be thinking of how and in what areas you might be able to trigger them. Continue to avoid areas where triggering these deeper slabs is more likely, such as steep convex rollovers and in areas with shallow snow often found in steep rocky terrain or scoured areas.

 

 

 

 


BOTTOM LINE

For today the avalanche hazard is rated HIGH. Continued precipitation with rising snow levels and temperatures, will cause very unstable conditions. This means that natural avalanches are likely and human triggered avalanches are very likely. Travel in avalanche terrain is not recommended. Flattop Mountain SNOTEL site, which is representative of the Flathead Range received an additional 1.4 inches of water weight in 24 hours bringing the storm total to 3.4 inches.

 

High 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: Once again, given this persistent slab problem, we need data/information. The accuracy of the avalanche advisory and our understanding of this persistent slab problem becomes much more robust when we have more information. Thus, observations from all of you are extremely valuable to us. Even it is just a simple email saying “Hey, we found good riding in Mountain Range X, and observed no signs of instability or recent avalanches”. This type of information is just as important as observations of avalanches. The observations need not be formal, and can remain anonymous. Don’t’ worry, we won’t give away your secret riding spot either. Call us at 406.261.9873 or email us at fac.admin@flatheadavalanche.org. Thanks for your help.

 


Community Avalanche Awareness Night!!! Join the new Friends of the Flathead Avalanche Center (FOFAC) for avalanche discussions followed by an opportunity to socialize with other winter backcountry enthusiasts.
March 6, 2014 (Thursday). 6:30 pm – 8:00 pm program and social afterwards. Moose Lodge, Whitefish. Details here.

New blog post by Ted Steiner about risk assessment in the backcountry here.

See recent snow profiles as well as snow profiles from the entire season here.

Join us March 14, 8:00 p.m. at Penco. We are working with the Flathead Snowmobile Association for the first in a series of motorized specific backcountry safety seminars. Details here.

Check out an interesting new research project that you can participate in about winter backcountry riding/snowmobiling and decision making from the Snow and Avalanche Lab at MSU. Details here.


Observations are extremely valuable to us. If you’ve been out in the backcountry, please drop us a line with your observations at fac.admin@flatheadavalanche.org or call 406.261.9873. Thanks!


DISCLAIMER

DisclaimerGraphic

This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.