Travel Advice

• Use caution as you transition into wind-exposed terrain and avoid freshly wind-loaded features.
• Use ridges and ribs to deke around large pillows of wind-transported snow at the top of slopes.
• When hill-climbing, turn back low in the slope before you hit any wind slabs near the top.
• Very large cornices may be overhanging north through east facing alpine slopes. They can fall unexpectedly, potentially triggering large avalanches. Give cornices a wide berth.
• Deep persistent weaknesses can lead to very large avalanches that are most likely to be triggered by surface avalanches stepping down, cornice falls, or by the weight of a person or sled on a thin-spot trigger point (e.g. a thin rocky area on a steep slope or moraine).

Snowpack Summary

Fresh snow and strong winds has left and will continue to form touchy hard and soft wind slabs down-wind of ridgecrests and terrain features on all aspects in exposed treeline and alpine areas. Recent warm temperatures resulted in a surface melt-freeze crust that will likely stay intact with the cooler forecast temperatures over the weekend. Large cornices are a threat in alpine areas, especially with any sun-exposure. Lower snowpack layers are likely to comprise facets and/or depth hoar, which could potentially be human-triggered from thin areas on rocky slopes with variable snowpack depth.

Weather Forecast

An unstable air mass is expected to bring continued light flurries throughout the weekend with around 5cm each day for Saturday and Sunday. Freezing levels could reach as high as 1000m during the day, and moderate southerly winds on Friday should shift to strong northeasterlies on Saturday and Sunday.

Prepared by Cam Campbell

Next Update: Thursday, April 18, 2013.

• Be alert for the formation of new wind slabs in the lee of terrain breaks such as ridges and ribs.
• Limit your exposure to avalanche terrain during periods of rapid loading from snow, wind or rain.
• Very large cornices may be overhanging north through east facing alpine slopes. They can fall unexpectedly, potentially triggering large avalanches. Give cornices a wide berth.
• Be cautious during periods of rain, when loose wet and wet slab avalanches may fail naturally.
• Beware of enhanced avalanche activity on steep south-facing slopes during sunny periods.
• Pay attention to overhead hazards. On warm days, start your trip early so you can be out of avalanche terrain before slopes heat up.
• Deep persistent weaknesses can lead to very large avalanches that are most likely to be triggered by surface avalanches stepping down, cornice falls, or by the weight of a person or sled on a thin-spot trigger point (e.g. a thin rocky area on a steep slope or moraine).

Snowpack Summary

Lots of snow drifting has been reported this week, creating new wind slabs in the lee of ridges and ribs. Recent very warm weather has led to a melt-freeze regime. The snowpack surface was melting and becoming weak with the sun’s heat by day, and refreezing at night. Many large avalanches were reported on east, south and south-east aspects. Large cornices are a threat, especially during times of warming. Lower snowpack layers are likely to comprise facets and/or depth hoar, which could potentially be human-triggered from thin areas on rocky slopes with variable snowpack depth.

Weather Forecast

Friday-Sunday: Precipitation is expected to fall as rain at lower elevations and as snow near treeline and above. Snow/rainfall amounts are expected to be light, but may be enhanced if cold air collides with a westerly flow. Expect moderate west to south-westerly winds. Freezing levels are uncertain, but could be as high as 2000 m on Saturday, falling by Sunday.

Prepared by Penny Goddard

Next Update: Thursday, April 11, 2013.

• This time of year, very large cornices are usually overhanging north through east facing alpine slopes and with significant daytime warming and sun-exposure they will likely become unstable.
• Beware of enhanced avalanche activity on steep south-facing slopes during sunny periods.
• Pay attention to overhead hazards and start your trip early in the day.
• Avoid traveling on or under steep south-facing slopes during the day when the sun is out or temperatures are warm.
• Slopes with corniced entrances, or exposed to cornice falls should be avoided with these conditions.
• Be aware that not only are cornice falls a danger in themselves, but they may also trigger old wind slab or large deep slab avalanches on the slopes below.
• Deep persistent weaknesses can lead to very large avalanches that are most likely to be triggered by surface avalanches stepping down, cornice falls, or by the weight of a person or sled on a thin-spot trigger point (e.g. a thin rocky area on a steep slope or moraine).

Snowpack Summary

There has been little snow in the past week, but consistent gusty winds have likely set up fresh and weak wind slab deposits on the leeward side of ridge crests and terrain features. Surface snow on sun-exposed slopes and at lower elevations has been subject to daily melt-freeze cycles, with morning crusts turning to afternoon slush.  Cornices are large and becoming weak with daytime warming and sun-exposure. Lower snowpack layers are likely to comprise of facets and/or depth hoar, which are most likely to be human-triggered from thin areas on rocky slopes with variable snowpack depth.

Weather Forecast

The Easter Weekend forecast is calling for mostly clear and dry conditions with occasional high clouds in the afternoon. Some light sporadic snow flurries may come on the weekend with only trace accumulations expected. Daytime freezing levels could reach as high as  2000 meters, but overnight temperatures should drop well below zero. Upper level winds are expected to remain in the moderate range from the west.

Prepared by Cam Campbell

Next Update: Thursday, April 4, 2013.

• Conditions are still primed for people triggering avalanches at higher elevations.
• Beware of enhanced avalanche activity on steep south-facing slopes during sunny periods.
• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
• Avoid common trigger points such as convex rolls.
• Watch for signs of instability like recent avalanches, whumpfs, or shooting cracks. If observed, back off to lower angled terrain.
• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Give cornices a wide berth when travelling on or below ridges.
• Deep persistent weaknesses can lead to very large avalanches that are most likely to be triggered by surface avalanches stepping down, cornice falls, or by the weight of a person or sled on a thin-spot trigger point (e.g. a thin rocky area on a steep slope or moraine).

Snowpack Summary

Western areas have seen around 20 cm new snow in the past week, while eastern areas have seen more like 5 cm. This sits on a previous storm slab layer that was another 20 cm or so thick. Gusty winds have likely set up wind slab deposits on the leeward side of ridge crests and terrain features. Cornices remain large. Lower snowpack layers are likely to comprise of facets and/or depth hoar.

Weather Forecast

Friday and Saturday: A mix of sun and cloud with a chance of flurries. Alpine temperatures around -8C. Light northwest winds.

Sunday: Clear and sunny. Daytime temperatures around -4C, but feeling a lot warmer on sunny aspects. Light northwest winds.

Prepared by James Floyer

Next Update: Thursday, March 28, 2013.

• Conditions are primed for people triggering avalanches.
• This is a good time to make conservative terrain choices.
• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
• Avoid common trigger points such as convex rolls.
• Watch for signs of instability like recent avalanches, whumpfs, or shooting cracks. If observed, back off to lower angled terrain.
• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Give cornices a wide berth when travelling on or below ridges.
• Deep persistent weaknesses can lead to very large avalanches that are most likely to be triggered by surface avalanches stepping down, cornice falls, or by the weight of a person or sled on a thin-spot trigger point (e.g. a thin rocky area on a steep slope or moraine).

Snowpack Summary

15-20cm of new snow at the beginning of the month and light amounts since has been redistributed by strong winds into deep and weak slabs on the leeward side of ridge crests and terrain features. Cornices are also large and precariously perched on ridge crests. A report from the North Fork of the Hummingbird drainage on March 9^th includes several recent large natural slab avalanches, some of which released down to the ground likely on a deep persistent weakness of facets and/or depth hoar.

Weather Forecast

Friday: A mix of sun and cloud with light flurries, moderate to strong westerly winds and valley bottom temperatures warming to -5 Celsius.

Saturday and Sunday: Snow flurries with 5-10cm of accumulation possible each day before clearing Sunday afternoon. Moderate southwesterly winds shifting to northwesterlies by Sunday, and valley bottom temperatures around -10 Celsius.

Prepared by Cam Campbell

Next Update: Thursday, March 21, 2013.

There are no recent observations from the region; however, based on weather station data and nearest neighbor observations it’s probably safe to assume that there was a decent amount of natural avalanche activity throughout the region last week. Most weather stations showed 20-35 cm of snow through last weekend. This is a heavy and rapid load on a weak and shallow snowpack.

• Avoid any large and steep slopes, especially rocky or sparsely treed slopes and areas with variable snow distribution.
• Avoid exposure to large south-facing slopes during the day when the sun is out, especially if the snow is becoming moist or wet.
• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Wind-loaded snow can rapidly overload weaknesses in the snowpack and cause natural avalanches.
• When climbing, be mindful of what is happening above you. Has the slope been recently loaded by new snow or wind? Is the sun impacting the snow above? If so, it may be best to choose an alternate route.  

Snowpack Summary

An estimate of 20-35 cm of new snow fell last week, most of which came during a large storm on March 1-3. It is likely this new snow was accompanied by decent west-southwest winds forming deep new wind slabs in exposed lee terrain. Watch for clues of wind loading like hollow sounding snow, cracking around skis or sleds, and scoured or deep looking areas. Recent sun and mild temperatures have likely caused loose wet avalanches on steeper south aspects, and formed a sun crust as temperatures cooled overnight. All of this new snow is sitting on a generally weak and faceted snowpack. It’s certainly possible for a rider to trigger a slab that releases on a weakness at or near the ground.

Weather Forecast

Friday: A mix of sun and cloud. The freezing level should jump from valley bottom to 1500 m during the day. Winds are light from the northwest.

Saturday and Sunday: Mainly sunny. The freezing level should jump to 1600 m during the afternoons. Winds are light from the west-northwest rising to moderate from the west on Sunday.

Outlook: A frontal system is forecast to move through BC and reach western Alberta by Monday. We could see moderate precipitation and mild temperatures for at least Monday and Tuesday.

Prepared by Peter Marshall

Next Update: Thursday, March 14, 2013.

• Forecast weather may lead to a significant change in snowpack characteristics this weekend.
• Wind-loaded snow and rain can rapidly overload weaknesses in the snowpack and cause natural avalanches. Be mindful of what is happening above you.
• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Facet layers below the surface could be triggered from shallow, rocky or sparsely treed areas.

Snowpack Summary

No new snow has fallen in the area since last weekend. Settled snowpack depths remain around 40 cm below treeline. Deeper snowpack areas and/or wind slabs are likely in wind loaded areas above treeline. Large cornices may be looming at ridge top, which could act as a trigger for avalanches on slopes below, or cause you harm on an ice route. Expect new storm snow and wind slab weaknesses to develop over the weekend. New snow may not bond well with current snowpack surfaces. Wind slabs are likely to be left behind in the wake of this system.

Weather Forecast

Friday: Mostly cloudy with light flurries, extreme southwesterly winds and freezing levels rising to over 2000m.

Saturday and Sunday: A warm, wet and windy weather system is expected to arrive on Saturday bringing as much as 20mm of precipitation by Sunday evening. Extreme southwesterly winds are expected to shift to strong northwesterlies by Sunday afternoon. Freezing levels are expected to be above 2000m on Saturday before dropping to valley bottoms on Sunday.

Prepared by Cam Campbell

Next Update: Thursday, March 7, 2013.

• Forecast weather may lead to a significant change in snowpack characteristics this week. Don’t be complacent about your exposure to avalanche terrain based on previous trips being problem-free.
• Wind-loaded snow can rapidly overload weaknesses in the snowpack and cause natural avalanches. It may be windy at ridge top, but sheltered if you are travelling in the trees. Be mindful of what is happening above you.
• What else is happening on slopes above you? Are slopes being baked by the sun, or are there cornices looming? Avoid parking yourself underneath this type of feature.
• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Facet layers below the surface could be triggered from shallow, rocky or sparsely treed areas.

Snowpack Summary

A few cm of new snow fell this week. Snowpack depths are around 40 cm below treeline. Deeper snowpack areas and/or wind slabs are likely in wind loaded areas above treeline. Large cornices may be looming at ridge top, which could act as a trigger for avalanches on slopes below, or cause you harm on an ice route. Expect new storm snow weaknesses to develop on Friday/Saturday, when up to 20 cm snow and very strong winds are expected. New snow may not bond well with current snowpack surfaces. Wind slabs are likely to be left behind in the wake of this system.

Weather Forecast

A cold front is due to affect the area by Friday afternoon, with around 15-20 cm snow and strong to extreme westerly winds. A brief ridge of high pressure over the weekend is replaced by a series of further frontal systems approaching from the west. These fronts are less likely to push significant precipitation into the region, but moderate to strong winds and light snow are expected.

Prepared by Penny Goddard

Next Update: Thursday, 28 Feb 2013.

Sledders:

• Use caution as you transition into wind affected terrain and avoid freshly wind loaded features.
• Ride on small, representative slopes with no consequence to get a feel for how the new snow crust is behaving before considering any bigger terrain.
• Deeper facet layers could be triggered from shallow/variable, rocky or sparsely treed areas, especially if the sun is causing the snowpack to become moist or wet.

Ice Climbers:

• Carefully assess overhead terrain for wind loading and cross-loading. Gusty winds could form new wind slabs that could fail naturally.
• Minimize your exposure to terrain traps where even a small sluff could have serious consequences.
• Choose routes that are not exposed from above during warm/sunny periods.

Snowpack Summary

Weather stations are indicating that the western side of the region received 10-15 cm of snow in the past week. It’s likely that there were also periods of moderate or strong northerly winds. New wind slabs have probably formed in exposed lee and cross-loaded terrain features. South facing slopes likely have a melt-freeze crust at or near the surface. The base of the snowpack is generally weak and faceted. The general distribution of snow is highly variable. The average snowpack depth in the region is 40-60 cm.

Weather Forecast

A progressive but persistent northwesterly flow over BC and western Alberta should result in mainly dry conditions for the Bighorn this weekend. Temperatures could be pretty warm on Friday afternoon with possible Chinook winds. The freezing level could jump up to 2000 m. A weakened system could drop a few cm’s of snow on Saturday with the freezing level dropping back to 1200-1400 m. The sun should return on Sunday with cooler temperatures and a freezing level near valley bottom.

Prepared by Peter Marshall

Next Update Thursday, 21-Feb-2013.

This conditions report is based on limited field observations and can therefore only provide generic information and advice based on past and anticipated weather. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Make sure to check out the latest Jasper National Park and the Banff National Park avalanche forecasts. These regions are just next door and conditions may be similar.

Travel Advice

Sledders:

• Assess carefully whether the wind has blown snow into deposits that overly a recently buried crust.
• Ride on small, representative slopes with no consequence to get a feel for how the new snow overlying the recent crust is behaving before considering any bigger terrain.
• Deeper facet layers might be triggered from shallow/variable, rocky or sparsely treed areas, especially if the sun is causing the snowpack to become moist or wet.

Ice Climbers:

• The recent freeze-thaw cycle has likely been good for ice formation. But you need to pay attention to the warm weather. Loose snow and/or slab avalanches become very likely on steep terrain when the temperature gets above 0C.
• Choose routes that are not exposed from above during warm/sunny periods.

Snowpack Summary

The upper snowpack consists of a few cm’s of dry new snow sitting on approximately 10 cm of settling storm snow from last week. There may be one or two crust layers in the upper snowpack, primarily on southerly aspects. The mid and lower snowpack is generally weak and faceted with a thick layer of depth hoar crystals near the base.

The general distribution of snow is highly variable. You are likely to find localized areas of deep wind slabs on leeward and cross-loaded slopes at and above treeline. The average snowpack depth in the region is 40-60 cm.

Weather Forecast

A strong ridge of high pressure should maintain dry conditions, sunny skies and mild temperatures for at least the next few days. We should see strong diurnal temperature swings with the freezing level dropping to surface overnight and 1000-1500 m during the day. Winds should be primarily from the northwest and strongest on Friday and Saturday.

Prepared by Peter Marshall

Next Update Thursday, 14-Feb-2013.

This conditions report is based on limited field observations and can therefore only provide generic information and advice based on past and anticipated weather. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Make sure to check out the latest Jasper National Park and the Banff National Park avalanche forecasts. These regions are just next door and conditions may be similar.

Travel Advice

Sledders:

• Assess carefully whether the wind has blown snow into deposits that overly the recent crust.
• Ride on small, representative slopes with no consequence to get a feel for how the new snow overlying the recent crust is behaving before considering any bigger terrain.
• Deeper facet layers might be triggered from shallow/variable, rocky or sparsely treed areas.

Ice Climbers:

• The recent freeze-thaw cycle has likely been good for ice formation. But you need to pay attention to the warm weather. Loose snow and/or slab avalanches become very likely on steep terrain when the temperature gets above 0C.
• Choose routes that are not exposed from above during warm/sunny periods.

Snowpack Summary

A recent storm (around 29^th, 30^th Jan) brought 10 cm or so of new snow that sits on top of a supportive crust. I suspect facets will lie above this crust on account of a short, but very cold pulse of cold air that came through after the crust formed in response to warm temperatures.

The general distribution of snow is highly variable. You are likely to find localized areas of deep wind slabs on leeward and cross-loaded slopes at and above treeline. Cold early season temperatures have faceted and weakened the lower snowpack.

Weather Forecast

It looks as though the region will have dry conditions through the weekend, with plenty of sunshine and mild temperatures. The brightest day currently looks to be Saturday, and freezing levels could rise as high as 2000 m. Winds should mostly be light and will initially be from the northwest. A switch in direction to southwesterly will occur on Sunday. Winds may increase for a few hours on Sunday morning as this shift takes place.

Prepared by James Floyer

Next Update Thursday, 07-Feb-2013.

This conditions report is based on limited field observations and can therefore only provide generic information and advice based on past and anticipated weather. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Make sure to check out the latest Jasper National Park and the Banff National Park avalanche forecasts. These regions are just next door and conditions may be similar.

Travel Advice

• Use caution as you transition into wind-exposed terrain and avoid freshly wind-loaded slopes.
• Watch out for shallow and variable, rocky or sparsely treed areas where deep persistent weaknesses are more likely to be triggered.
• Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack. If observed, back-off to lower angled terrain.

• Remember even a small sluff can know you off your perch and have dire consequences if you are not well-protected, or if you hit a ledge, etc.

Snowpack Summary

Recent reports suggest that a shallow, variable snowpack exists with only a light dusting of snow in the past week. But expect to find localized areas of deep wind slabs on leeward and cross-loaded slopes at and above treeline. Cold early season temperatures has faceted and weakened the lower snowpack and recent warming has and wind created a surface crust which is now down 2-5cm.

Weather Forecast

Expect generally cloudy conditions with light snow flurries throughout the weekend. Moderate southwesterly winds on Friday should ease to light northwesterlies by Saturday and pick up again from the southwest on Sunday. Freezing levels are expected to remain in valley bottoms with treeline temperatures in the -10 to -15 Celsius range.

Prepared by Cam Campbell

Next Update Thursday, Jan. 31, 2013.

This conditions report is based on limited field observations and can therefore only provide generic information and advice based on past and anticipated weather. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Make sure to check out the latest Jasper National Park and the Banff National Park avalanche forecasts. These regions are just next door and conditions may be similar.

Travel Advice

Be aware that warm temperatures, especially if it gets above freezing and/or coupled with intense sun-exposure, can have a significant destabilizing effect on the snowpack. If you’re planning on climbing a route, make sure to check the weather forecast with this in mind before heading out. If it’s going to be warm and sunny, stick to north facing routes with no overhead exposure, and back-off if the snow surface becomes wet or sticky. Remember even a small sluff can know you off your perch and have dire consequences if you are not well-protected, or if you hit a ledge, etc.

Snowpack Summary

Recent reports suggest that a shallow, variable snowpack exists with only a light dusting of snow since in the past week. But expect to find localized areas of deep wind slabs on leeward and cross-loaded slopes at and above treeline. Cold early season temperatures has faceted and weakened the lower snowpack and recent warming has moistened the surface snow at lower elevations, and made the overlying slab more sensitive to triggers at all elevations.

Weather Forecast

Expect generally cloudy conditions with isolated light showers or flurries throughout the weekend. Moderate westerly winds on Friday should ease to light northwesterlies by Saturday. Freezing levels are expected to climb above valley bottoms each day and rise significantly again on Monday, but cold air may still be trapped in some valley bottoms, resulting in temperature inversions, and possible freezing rain.

Prepared by Cam Campbell

Next Update Thursday, Jan. 24, 2013.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Make sure to check out the latest Jasper National Park and the Banff National Park avalanche forecasts. These regions are just next door and conditions may be similar.

Travel Advice

A common theme in the many of the fatal accidents in the area has been temperature inversions. It may seem cold in the valley bottoms at the base of your route, but up high the snowpack is warming up and becoming unstable. Such a temperature inversion could happen early next week, so if you’re planning on climbing a route with overhead exposure, make sure to check the weather forecast with this in mind before heading out. If a temperature inversion is expected, stick to low elevation routes with no overhead exposure.

Remember that even when the route looks bare, wind can deposit unstable pockets of snow in unexpected places, which can be big enough to release deadly avalanches. Even a small avalanche can kill you if it pushes you off a cliff. It is important that ice climbers always wear a helmet and belay from a sheltered location out of harm’s way.

Avalanche Activity

Recent reports from the Bighorn region include a few relatively harmless loose snow avalanches on southeast aspects in the alpine. Recent reports from neighbouring regions include several loose snow avalanches on steep slopes and in gullies below treeline involving recent storm snow and scouring the thin faceted snowpack right down to the ground. Although small, these avalanches could certainly knock you off your perch and have serious consequences if terrain traps are in the runout.

Snowpack Summary

Recent reports suggest that a shallow, variable snowpack exists with only a light dusting of snow since the new year. Clear skies and cool temperatures have probably contributed to the deterioration of the snowpack through faceting. Surface hoar may be found at the snow surface, which could become a weak layer once buried with new snow. Expect to find localized areas of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

A mix of sun and clouds with isolated light flurries is expected throughout the weekend. Light northwesterly winds and treeline temperatures in the -15 to -20 Celsius range. Forecast models are currently calling for a temperature inversion with significant warming at higher elevations to start on Sunday night.

Prepared by Cam Campbell

Next Update Thursday, Jan. 17, 2013.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Click here for the latest Jasper National Park Avalanche Forecast. Jasper Park is the next door neighbour and conditions may be similar.

Our fatality statistics tell us that most early-season fatal avalanche accidents have occurred on the east slopes of the Rocky Mountains. Between 1996 and 2008, 14 people died in avalanches between mid-October and early December, and of those fatalities, 10 occurred on the east slopes of the Rockies, most of whom were ice climbers.

Travel Advice

If you’re ice climbing, be mindful of slopes above which might be getting wind-loaded or heated by the sun. Even a small avalanche can cause serious harm if it hits you on a climb. Choose days with cool temperatures, cloud cover, little wind and no precipitation to tackle climbs which have avalanche slopes above.

The ongoing effect of winds on the snowpack means that the best riding areas are often the most wind-loaded. Clues of wind slab conditions include: ‘fat’ looking slopes, drummy, hollow sounds or cracking. If you encounter these, back off and try a slope facing a different direction, which may not be so wind-loaded.

Avalanche Activity

No recent avalanches have been reported. In neighbouring regions, loose snow avalanches have been observed in response to solar warming.

Snowpack Summary

Recent reports suggest that a shallow, variable snowpack exists. It’s been a dry week. Clear skies and cool temperatures have probably contributed to the deterioration of the snowpack through faceting. Surface hoar may be found at the snow surface, which could become a weak layer once buried with new snow. In the alpine, unseasonably warm temperatures (caused by a temperature inversion) may have moistened snow on sunny slopes, leaving behind a sun crust.

Expect to find localized areas of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

Friday: Overcast skies with the possibility of 1-2 cm of snow. Alpine temperatures near -10. Moderate to strong NW/W winds.

Saturday: Mix of sun and cloud. Light to moderate SW winds. Clear.

Sunday: Light snow. Moderate SW winds.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Click here for the latest Jasper National Park Avalanche Forecast. Jasper Park is the next door neighbour and conditions may be similar.

Our fatality statistics tell us that most early-season fatal avalanche accidents have occurred on the east slopes of the Rocky Mountains. Between 1996 and 2008, 14 people died in avalanches between mid-October and early December, and of those fatalities, 10 occurred on the east slopes of the Rockies, most of whom were ice climbers.

Travel Advice

Remember that even when a lower elevation ice climbing route looks bare, wind can deposit unstable pockets of snow in unexpected places above, which can be big enough to release deadly avalanches. Even a small avalanche can kill you if it pushes you off a cliff. It is important that ice climbers belay from a sheltered location out of harm’s way.

Remember that in heavily wind-scoured terrain, the only slopes with enough snow for riding have probably been wind-loaded.

Avalanche Activity

No recent avalanches have been reported. This may speak more to a lack of observations than actual conditions. In some isolated areas at high elevations the wind may have drifted enough snow into pockets that an avalanche might be possible.

Snowpack Summary

Recent reports suggest the total snowpack depth is around 20-35cm at treeline and 20-30cm below treeline. In the past week there has been less than 5cm of new snow which may have fallen on a rain crust in some locations. Recent cold temperatures have, no doubt, contributed to some faceting (weak sugar snow) throughout the snowpack. Expect to find localized pockets of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

We expect a mix of sun and cloud throughout Friday and the weekend. Winds should be moderate from the southwest on Friday switching to moderate and northwesterly on Saturday and Sunday. Ridgetop temperatures should stay between -12.0 and -16.0.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Click here for the latest Jasper National Park Avalanche Forecast. Jasper Park is the next door neighbour and conditions may be similar.

Our fatality statistics tell us that most early-season fatal avalanche accidents have occurred on the east slopes of the Rocky Mountains. Between 1996 and 2008, 14 people died in avalanches between mid-October and early December, and of those fatalities, 10 occurred on the east slopes of the Rockies, most of whom were ice climbers.

Travel Advice

Remember that even when the route looks bare, wind can deposit unstable pockets of snow in unexpected places, which can be big enough to release deadly avalanches. Even a small avalanche can kill you if it pushes you off a cliff. It is important that ice climbers always wear a helmet and belay from a sheltered location out of harm’s way.

Avalanche Activity

In some isolated areas at high elevations the wind may have drifted enough snow into pockets that an avalanche might be possible.

Snowpack Summary

Recent reports suggest the total snowpack depth is around 20-35cm at treeline and 20-30cm below treeline. It is generally soft snow, but supports a sled. In the past week there has been less than 5cm of new snow and a bit of rain as well, but since then the temperatures have plummeted. Expect to find localized pockets of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

Friday: Light snow in the morning and evening with moderate southwesterly winds, and valley bottom temperatures around -15 Celsius. Saturday: Light snow increasing throughout the day with moderate southwesterly winds becoming strong southeasterlies, and valley bottom temperatures around -10 to -15 Celsius.  Sunday: Mostly cloudy with isolated flurries, light to moderate northwesterly winds and valley bottom temperatures around -10 to -15 Celsius.

Prepared by Cam Campbell

Next Update Thursday, Dec. 27, 2012.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. In fact, there has been no new information in the past week. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Click here for the latest Jasper National Park Avalanche Forecast. Jasper Park is the next door neighbour and conditions may be similar.

Our fatality statistics tell us that most early-season fatal avalanche accidents have occurred on the east slopes of the Rocky Mountains. Between 1996 and 2008, 14 people died in avalanches between mid-October and early December, and of those fatalities, 10 occurred on the east slopes of the Rockies, most of whom were ice climbers.

Travel Advice

Remember that even when the route looks bare, wind can deposit unstable pockets of snow in unexpected places, which can be big enough to release deadly avalanches. Even a small avalanche can kill you if it pushes you off a cliff. It is important that ice climbers always wear a helmet and belay from a sheltered location out of harms way.

Avalanche Activity

In some isolated areas at high elevations the wind may have drifted enough snow into pockets that an avalanche might be possible.

Snowpack Summary

Expect to find localized pockets of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

Friday: Light snow with moderate westerly winds. Freezing levels in valley bottoms with alpine temperatures around -15 Celsius. Saturday: Clearing overnight Friday, but light snow should start again Saturday morning with strong southwesterly winds ad alpine temperatures around -10 to -15 Celsius.  Sunday: Continued light snow but winds should ease and temperatures should drop.

Prepared by Cam Campbell

Next Update Thursday, Dec. 20, 2012.

This conditions report depends on weather and snowpack data coming in from professionals and recreationists in the field, and there is currently limited information to work with. It is important that people garner local knowledge before heading out and make their own observations while in the mountains. If you see something interesting in the field, please let us know about it. You can send observations to: forecaster@avalanche.ca, call (250) 837-6405, or post it on the Central Rockies Discussion Forum.

Click here for the latest Jasper National Park Avalanche Forecast. Jasper Park is the next door neighbour and conditions may be similar.

Our fatality statistics tell us that most early-season fatal avalanche accidents have occurred on the east slopes of the Rocky Mountains. Between 1996 and 2008, 14 people died in avalanches between mid-October and early December, and of those fatalities, 10 occurred on the east slopes of the Rockies, most of whom were ice climbers.

Travel Advice

Remember that even when the route looks bare, wind can deposit unstable pockets of snow in unexpected places, which can be big enough to release deadly avalanches. Even a small avalanche can kill you if it pushes you off a cliff. It is important that ice climbers always wear a helmet and belay from a sheltered location out of harms way.

Avalanche Activity

In some isolated areas at high elevations the wind may have drifted enough snow into pockets that an avalanche might be possible.

Snowpack Summary

Expect to find localized pockets of wind slabs on leeward and cross-loaded slopes at and above treeline.

Weather Forecast

Friday and Saturday: Partly cloudy with isolated flurries, alpine temperatures around -15 Celsius, and moderate becoming light southwesterly winds. Sunday: Mostly clear and dry, alpine temperatures around -20 Celsius and moderate westerly winds increasing to strong northweaterlies throughout the day.

The weekly avalanche report for the Bighorn has ended for this season. You can find general advice for managing avalanche hazard at this time of year in the sections below. Additional, more detailed information, can be found in the Forecaster Blog.

Primary Avalanche Concerns

Loose Wet: Snow stability can deteriorate very quickly with warm spring temperatures. Watch for loose wet avalanches on steep terrain, especially under direct solar radiation.

Wet Slabs: Wet slabs tend to occur on steep south-facing slopes during periods of prolonged warming. During heavy rain or exceptionally warm temperatuers, wet slabs become more likely on all aspects.

Cornices: Large cornices exist in alpine terrain. A failure could be destructive by itself, and could also trigger an avalanche on the slope below.

Avalanche Summary

During spring conditions, avalanches are most likely to occur in response to solar radiation, warm temperatures, and periods of rain. Particularly dangerous conditions may develop during prolonged periods of warming, heavy rain, or on days with no overnight freeze. Under these conditions, surface avalanches may step down and trigger deeper wet slab avalanches. Prolonged warming may also weaken large and destructive cornices, which are a danger in themselves or could act as a heavy trigger on the slope below. Typically, avalanche activity ramps up during the day and is at a peak during the afternoon. If it's raining or there was no overnight freeze, avalanche activity can happen at any time.

Snowpack Summary

At this time of year, the surface layers have a great deal of influence on the snowpack. When there is a solid re-frozen surface crust, travel is fast and easy, and the snowpack is held together by the surface cap. Any deeper persistent weak layers are unlikely to fail until the surface cap breaks down from daytime heating. During warm conditions, melt water is able to percolate within the snowpack and cause deeper weak layers to fail. If it cools off and snows, new snow may not bond well to the hard spring crusts, and isolated storm and wind slabs can easily develop.

A Note of Thanks

The CAC would like to extend a note of thanks to observers in the region who sent us reports this winter. These observations enable us to produce this report.

Current Field Report

New snow in this region has given elevated avalanche concerns in the Bighorn high country. Up to 25 cm new snow will likely become unstable on steep slopes, during the storm on Friday and for several days afterwards. If we get clearing skies and warmer temperatures (likely towards the end of the weekend or early next week) the new snow will become further destabilized and further avalanche activity can be expected.

Avalanche Problems

1.    Storm and Wind Slabs

New storm slabs and wind slabs are likely, particularly in exposed leeward terrain and cross-loaded gullies. These slabs could release naturally during the storm on Friday, or in response to sled/human triggers by riding on unstable slopes.

2.  Loose Wet Avalanches

Warm weather with some sunshine is expected to return to the area by the end of the weekend or early next week. Expect loose wet avalanches on sun-exposed slopes in the afternoon.

3.    Wet Slabs

During prolonged periods of warm temperatures, melt water percolating through the snowpack can activate more deeply buried weak layers. Crusts are particularly susceptible to this. Full depth avalanches running to ground are also possible during these kinds of conditions, especially where the terrain below is smooth or rocky.

Travel Advice

• Don’t ride on or under steep, unsupported slopes for at least 48 hours after a significant snowfall.
• If you see obvious signs of weakness, such as previous avalanche activity, cracks under your sled or you feel whumpfs on flat terrain, it means the snowpack is likely to be unstable. Avoid open bowls and steep lines if this is what you see.
• Be aware of cornices, which are large and drooping. Cornices are a hazard in themselves and could also release deeper, destructive avalanches on the slope below.
• Avoid sun-exposed slopes in the afternoon if it is warm and the snow is moist or wet.

Avalanche Summary

Avalanche activity was observed last weekend (07-08 April) in the high country. Cornice releases were noted, which had pulled out slabs on the slope below, in some cases stepping down to some of the lower layers within the snowpack.

I anticipate avalanche activity will occur in response to the storm on Thursday night/Friday. Further activity is expected the next time things warm up again and the sun makes a re-appearance.

Snowpack Summary

By the weekend, I expect a reasonable amount of dense new snow to be sitting on old snow surfaces in many areas in the Bighorn. The old snow comprises a crusty, sun-baked and temperature affected surface in most areas. The bond between the new snow and the old surface needs to be carefully monitored. Where there is a crust at the new/old snow interface, it is likely to act as a good sliding layer. Winds have generally been fairly light. However, exposed lee slopes could easily generate areas of wind slab that need to be watched out for.

Lower in the snowpack, you may be able to dig down and find decomposing surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, weak sugary crystals are prominent. Typical snowpack depth at treeline elevations is around 50-70 cm.

Weather Forecast:

Overnight Thursday and into Friday will likely see some enhanced precipitation for this region, with up to 25 cm new snow forecast. Freezing level will be around 1500 m, winds moderate from the northwest. On Saturday, there will be lingering light snowfall, freezing level will drop to around 1000 m and the winds will gradually diminish. On Sunday, the region should become dry, but remain cloudy with only the occasional sunny break. Freezing levels will return to around 1500 m. Winds light.

Prepared by: James Floyer

Current Field Report

There has been light to moderate snow accumulations in the past week. Around 5-10cm fell last weekend, with another 10-15cm being reported on Wednesday. This snowfall was accompanied by moderate or strong winds. Temperatures continue to rise and fall with daytime warming and overnight cooling. Valley bottom temperatures are reaching into the double digits now, but dropping back below 0 overnight. Southerly aspects are experiencing a melt-freeze cycle with a strong crust developing at higher elevations. All aspects have developing moist snow up to about 2200 metres at some point during the week.

Avalanche Problems

1.    Wind Slabs

New wind slabs are likely in exposed leeward terrain and cross-loaded gullies. These wind slabs could release naturally with daytime warming and solar radiation, or from the weight of a person.

2.  Loose Wet Avalanches

Strong solar radiation is likely this week. Expect loose wet avalanches on sun-exposed slopes in the afternoon, and the potential for larger wet slabs as temperatures gradually rise through the period.

3.    Persistent Slabs

Weak sugary facets and depth hoar exist at the base of the snowpack. Initial warming of the snowpack may result in full depth avalanche releases. Well-developed melt-freeze crusts may bridge the upper snowpack in the mornings after a good re-freeze, and then provide little or no support in the afternoons when the crust breaks down.

Travel Advice

• If you see obvious signs of weakness, such as previous avalanche activity, cracks under your sled or you feel whumpfs on flat terrain, it means the snowpack is likely to be unstable. Avoid open bowls and steep lines if this is what you see.
• Be aware of overhead exposure. Conditions could change very quickly with elevation. Weak wind slabs could be lurking in gullies and overhanging cornices could pop off with daytime warming.
• Avoid sun-exposed slopes in the afternoon if it is warm and the snow is moist or wet.

Avalanche Summary

We don’t have any reports of new avalanches from the region. New wind slabs may release easily under the weight of a person or from daytime warming and solar radiation. I suspect that moist releases from steep thin or rocky areas will continue during periods of warm sunny weather.

Snowpack Summary

With recent strong winds and new snow, expect wind slab deposits on the downwind side of ridges, rolls and other terrain features. Some exposed areas in the alpine have been scoured down to the rock, and other sheltered areas have had more than normal amounts deposited by the wind. You may be able to dig down and find surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, however, weak sugary crystals are prominent. Typical snowpack depth at treeline elevations is around 50-70 cm.

Weather Forecast:

Unsettled weather is forecast for the next few days. There are no large systems forecast, but there may be periods of convective flurries that bring short snowfalls. Upper level winds are expected to be light to moderate from the northwest to southwest, but surface winds may be gusty and variable during periods of flurries. Many days will see a significant amount of sunshine as well, especially this coming weekend. Freezing levels should gradually rise throughout the period from 1000m on Friday to 1500-2000m by the middle of the week.

Prepared by: Peter Marshall

Next Update: Thursday April 12, 2012

Current Field Report

There has been very little precipitation in the region over the past week. The weather station at Job Creek (2000 metres) has only recorded 2-3 mm in the past 7 days, and only about 6 mm since March 14^th. The temperature at 2000 metres has dipped down to about -4.0 C. over the past few nights, and has risen to about +4.0 during the heat of the day. Southerly aspects are experiencing a melt-freeze cycle with a strong crust developing at5 higher elevations. All aspects are developing moist snow up to about 2200 metres. Snowballing and moist avalanche releases have been reported in the afternoons. 

Avalanche Problems

1. 1.    Persistent Slabs

Weak sugary facets and depth hoar exist at the base of the snowpack. Initial warming of the snowpack may result in full depth avalanche releases. Well developed melt-freeze crusts may bridge the upper snowpack in the mornings after a good re-freeze, and then provide no support in the afternoons when the crust approaches 0.0 C.

2.  Loose Wet Avalanches

Forecast unsettled weather may bring some periods of broken or clear skies to the region over the weekend. Strong solar radiation during these periods may cause on sun-exposed slopes.

3.    Wind Slabs

Old windslabs may be lingering at higher elevations on northerly aspects. Possible upslope conditions on Sunday may cause new windslabs to develop on south through west aspects. The new snow may not bond to the old crust.

Travel Advice

• If you see obvious signs of weakness, such as previous avalanche activity, cracks under your sled or you feel whumpfs on flat terrain, it means the snowpack is likely to be unstable. Avoid open bowls and steep lines if this is what you see.
• Avoid regrouping in areas with an overhead hazard as avalanches may have the potential to run full path.
• Avoid sun-exposed slopes in the afternoon if it is warm and the snow is moist or wet.

Avalanche Summary

We don’t have any reports of new avalanches from the region. I suspect that moist releases from steep thin or rocky areas will continue during periods of warm sunny weather. If there is a dry upslope storm on Sunday from the East, the new snow may not bond to areas with a previous crust.

Snowpack Summary

It has been very windy at times in this region this winter. Some exposed areas in the alpine have been scoured down to the rock, and other sheltered areas have had more than normal amounts deposited by the wind. In some areas the only snow available for travel may be the strip of drifted snow that has been cross-loaded between two ridges. Typical snowpack depth at treeline elevations is around 50-70 cm. With recent strong winds, expect wind slab deposits on the downwind side of ridges, rolls and other terrain features. You may be able to dig down and find surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, however, weak sugary crystals are prominent.

Weather Forecast:

Unsettled weather is forecast for the next few days. There are no large systems forecast, but there may be periods of convective flurries that bring short intense snowfalls. Upper level steering winds are expected to be light to moderate from the southwest, but surface winds may be gusty and variable during periods of flurries. On Sunday there is a chance that a low pressure system that is moving out of the southern Rockies may be pushed back up against the central Rockies. If this upslope storm happens, expect about 10-20 mm of precipitation combined with light to moderate easterly winds that may generate 20-30 cm of snow as it rises into the cooler airmass in the mountains. The long range outlook has not identified any other major systems.

Prepared by: Tom Riley

Next Update: Thursday April 5, 2012

Elevated avalanche conditions exist at present in the Bighorn. Exercise caution when traveling in the mountains at this time.

Current Field Report

The past week saw only trace amounts of snowfall with periods of strong wind. While overnight temperatures dipped to below -10.0, daytime temperatures hovered at about 0.0. A natural avalanche cycle has taken place with more avalanche activity expected with forecast warm temperatures. It's still a good time to exercise caution when traveling in the Bighorn backcountry at this time.

Avalanche Problems

1.  Persistent Slabs

Near the base of the snowpack, sugary facets exist. Warm temperatures or an avalanche triggered in the more recent storm snow could easily step down to the lower layers, resulting in a large, destructive avalanche.

2.  Loose Wet Avalanches

Forecast solar radiation indicates that there will most likely be an increase in avalanche activity on sun-exposed slopes.

3.    Wind Slabs

Recently formed wind slabs may exist on lee features and may be triggered on steep, unsupported terrain.

Travel Advice

• If you see obvious signs of weakness, such as previous avalanche activity, cracks under your sled or you feel whumpfs on flat terrain, it means the snowpack is likely to be unstable. Avoid open bowls and steep lines if this is what you see.
• Avoid regrouping in areas with an overhead hazard as avalanches may have the potential to run full path.
• -Avoid sun-exposed slopes

Avalanche Summary

An avalanche cycle has occurred in response to recent warm temperatures producing avalanches "large enough to bury a car".

Looking ahead, natural avalanches are expected to continue as the same weak snowpack structure exists with more warming on the way.

Snowpack Summary

Typical snowpack depth at treeline elevations is around 50-70 cm. However, in deep places, where the wind has blown the new snow into drifts, significantly deeper accumulations exist. With recent strong winds, expect wind slab deposits on the downwind side of ridges, rolls and other terrain features. You may be able to dig down and find surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, however, weak sugary crystals are prominent.

Weather Forecast:

On Friday we expect a mix of sun and cloud with light and variable winds. On Friday, freezing levels are forecast to remain at surface. A clearing trend is expected this weekend and into early next week with rising freezing levels, strong solar input and generally light southwest ridgetop winds.

Prepared by: Joe Lammers

Next Update: Thursday March 29, 2012

Elevated avalanche conditions exist at present in the Bighorn. Exercise caution when traveling in the mountains at this time.

Current Field Report

Recent storms have added further snow (15 cm in the west, 5 cm in the east) to the large snowfall (40 cm+) that occurred last week. While natural avalanche activity has subsided, many slopes remain primed for human triggers, such as a sled in the wrong place. It's still a good time to exercise caution when traveling in the Bighorn backcountry at this time.

1.  Storm Slabs and Wind Slabs

Ongoing snowfall with winds in the 40-50 km/h range have contined to load up downwind slopes, behind ridgelines, off summits and on the lee of smaller terrain features such as roll-overs. These are probably the most likely place you can get into trouble right now.

2.  Persistent Slabs

Near the base of the snowpack, sugary facets exist. An avalanche triggered in the more recent storm snow could easily step down to the lower layers, resulting in a large, destructive avalanche.

Travel Advice

• Avoid riding over wind loaded rolls and ridgelines.
• It's not a good time for highmarking or hillclimbing big slopes at this time.
• If you see obvious signs of weakness, such as previous avalanche activity, cracks under your sled or you feel whumpfs on flat terrain, it means the snowpack is likely to be unstable. Avoid open bowls and steep lines if this is what you see.

Avalanche Summary

We haven't heard reports of specific avalanches from this region. However, that doesn't mean they haven't been happening, just that we haven't been hearing of them. The neighbouring Mountain Parks to the west have been having an active period of avalanche activity in the last week, with avalanches up to size 3 reported.

Looking ahead, the next issue to be concerned with is intense solar warming, which is likely this weekend and will be the first warming event for a while. This may destabilize the recent new snow and spark off some large events.

Snowpack Summary

Typical snowpack depth at treeline elevations is around 50-70 cm. However, in deep places, where the wind has blown the new snow into drifts, significantly deeper accumulations exist. With recent SW and NW winds, expect wind slab deposits on the downwind side of ridges, rolls and other terrain features. You may be able to dig down and find surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, however, weak sugary crystals are prominent.

Weather Forecast

Friday: A mix of sun and cloud with a chance of flurries in the west. Treeline temperatures around -2C. Winds light to moderate southwesterly.

Saturday: Significant periods of sunshine in the morning. Possibly clouding over with a chance of flurries in the afternoon. Treeline temperatures around -4C. Winds initially light, picking up from the south in the afternoon.

Sunday: Sunshine, with light or calm winds. Treeline temperatures dropping to around -10C.

Prepared by: James Floyer

Next Update: Thursday March 22, 2012

Elevated avalanche conditions exist at present in the Bighorn. Exercise caution when traveling in the mountains at this time.

Current Field Report

Recent storms have brought around 40 cm new snow to this region, which has resulted in natural avalanches running in several areas. As this new snow consolidates and forms a slab, larger, more dangerous avalanches become a possibility.

1.  Storm Slabs

Significant amounts of new snow have fallen in the last few days in this region. This new snow has started to consolidate into a slab, giving it the strength it needs to release dangerous slab avalanches. I suspect the bond between the old snow and the recent storm snow may not be that good, further enhancing the chance of triggering a slab avalanche.

2.  Wind Slabs

Extensive wind transport has deposited new snow onto the lee (downwind) side of ridges and terrain features in exposed areas.

3.  Persistent Slabs

Near the base of the snowpack, sugary facets exist. An avalanche triggered in the more recent storm snow could easily step down to the lower layers, resulting in a large, destructive avalanche.

Avalanche Summary

A few relatively small avalanches have been observed that have mostly been loose snow sluffs. The concern is that with anticipated warm temperatures the surface will start to consolidate, but (initially at least) not enough to stabilize, increasing the likelihood of a slab avalanche. In thicker, wind drifted areas, deeper deposits will have the potential to release larger avalanches. There is also the possibility for avalanches to step down to lower weak layers.

Snowpack Summary

Typical snowpack depth at treeline elevations is around 50-70 cm. However, in deep places, where the wind has blown the new snow into drifts, significantly deeper accumulations exist. With recent SW and NW winds, expect wind slab deposits on the downwind side of ridges, rolls and other terrain features. You may be able to dig down and find surface hoar crystals buried around 30-40 cm under the surface. Below this interface, the midpack is relatively cohesive and strong. At the base of the snowpack, however, weak sugary crystals are prominent.

Weather Forecast

Warm temperatures are expected to be a feature into Friday, with freezing levels around 2000 m. A pulse of precipitation is expected for Friday, with amounts in the 5-10 mm range. This could fall as rain in many spots due to the warm temperatures. Winds are expected to be strong southwesterly.

For the weekend, ongoing flurries are likely, interspersed with clearing breaks. Winds should diminish but remain in the moderate range from the southwest. By Monday, temperatures should drop back down to the 800-1000 m range.

Prepared by: James Floyer

Next Update Thursday March 15, 2012

The Bighorn remains a black hole of information. If you do a trip in this region, please let us know what you are seeing out there, email: forecaster@avalanche.ca

Current Field Report

The region has seen limited change over the past week. A couple of pulses of precipitation have dropped up to 10cm of new snow and winds have been consistent westerly. Avalanche problems remain similar to previous reports:

1.  Persistent Slabs

The Bighorn region has a notoriously shallow snowpack. The bottom of the snowpack typically forms into large sugary crystals that do not bond well to one another. With cohesive snow over top of this weakness, the concern is that a rider triggers through the firm snow down to the loose snow at the bottom. Be aware of thinner areas around ridgecrests and rocks that allow for deeper triggering.

2.  Wind Slabs

Some snow drifting from ridges was recently observed, so expect to encounter weak wind slabs below ridgecrests and behind terrain breaks.

3.  Cornice Fall

Many east facing ridgelines are sporting large unsupported cornices.  A failing cornice could trigger a deep slab avalanche. Also, even a small cornice release can be compounded dramatically if you are travelling in a gully feature where popular ice climbs form. Stay aware of what’s above you and what the ridgetop winds are doing.

Avalanche Summary

A few recent small natural sluffs were observed on southeast facing alpine slopes.

Snowpack Summary

Total snowpack depth at treeline elevations is in the 30-40cm range, but recent reports suggest it can be as deep as 80cm, with slightly more in the alpine and slightly less below treeline. The surface snow is predominantly wind pressed, with weak surface hoar buried by up to 15 cm of recent snow. This could be deeper in wind affected areas.  Under that interface, the mid pack is cohesive and strong, but this all sits on top of weak sugary snow near the ground.

Weather Forecast

Generally cloudy with sunny breaks and isolated light flurries for the weekend. Winds are expected to be light from the west and freezing levels should remain in valley bottoms.

Prepared by Cam Campbell

Next Update Thursday March 8, 2012

The Bighorn remains a black hole of information. If you do a trip in this region, please let us know what you are seeing out there, email: forecaster@avalanche.ca

Current Field Report

The region has seen limited change over the past week. A couple of pulses of precipitation have dropped up to 10cm of new snow and winds have been consistent westerly. Avalanche problems remain similar to previous reports:

1.  Persistent Slabs

The Bighorn region has a notoriously shallow snowpack. The bottom of the snowpack typically forms into large sugary crystals that do not bond well to one another. With cohesive snow over top of this weakness, the concern is that a rider triggers through the firm snow down to the loose snow at the bottom. Be aware of thinner areas around ridgecrests and rocks that allow for deeper triggering.

2.  Wind Slabs

While there has only been a small amount of new snow, the new snow fell on weak surface hoar and slick sun crust, which are both prone to avalanche formation.  With recent moderate westerly winds, expect windslabs on lee features at treeline and in the alpine.

3.  Cornice Fall

Many east facing ridgelines are sporting large unsupported cornices.  A failing cornice could trigger a deep slab avalanche. Also, even a small cornice release can be compounded dramatically if you are travelling in a gully feature where popular ice climbs form. Stay aware of what’s above you and what the ridgetop winds are doing.

Avalanche Summary

No recent avalanche activity has been reported.  But, that doesn’t mean that avalanches haven’t occurred.  If you see recent activity while you’re out this weekend, please take a photo and let us know about it via email: forecaster@avalanche.ca or phone: 250-837-2141 Ext. 230

Snowpack Summary

The surface snow is predominantly wind pressed, with weak surface hoar buried by up to 15 cm of recent snow. This could be deeper in wind affected areas.  Under that interface, the mid pack is cohesive and strong, but this all sits on top of weak sugary snow near the ground.  The snowpack is deep enough for sledding with around 80 cm reported near treeline.

Weather Forecast

Expect clouds to build Friday, with a chance of flurries later in the day. Flurries will continue through Saturday, with accumulations reaching up to 10cm. Daytime temperatures should reach -5 with continued westerly flow. Sunday and Monday will see the clouds moving out of the region, as mostly clear skies arrive with cooler temperatures.

Prepared by Matt Peter

Next Update Thursday March 1, 2012

We have limited field observations from the Bighorn; please let us know what you are seeing out there, email: forecaster@avalanche.ca

Current Field Report

Weather is the architect of avalanches, and as of late, it seems like the architect has been on holiday.  With very little change in the weather, the major avalanche problems look a lot like they did last week.  Anyone headed into the backcountry this weekend should be thinking about the following avalanche problems:

1.  Deep Persistent Slabs

This region is notorious for harboring shallow weak snow.  A deep slab release is unlikely, but a large trigger, such as cornice fall, could trigger a very large avalanche failing near the ground.

2.  Wind Slabs

While there has only been a small amount of snow this week, the new snow fell on weak surface hoar and slick sun crust, which are both prone to avalanche formation with potentially wide propagation.  With recent moderate westerly winds, expect windslabs on lee features.

3.  Cornice Fall

Many east facing ridgelines are sporting large unsupported cornices.  A failing cornice would result in large chunks of dense snow impacting slopes below ridge crest which could trigger a deep slab avalanche.

Avalanche Summary

No recent avalanche activity has been reported.  But, that doesn’t mean that avalanches haven’t occurred.  If you see recent activity while you’re out this weekend, please take a photo and let us know about it via email: forecaster@avalanche.ca or phone: 250-837-2141 Ext. 230

Snowpack Summary

The current snowpack is a bit of a weakness sandwich.  Weak surface hoar is now buried 5 – 10 cm below the snow surface.  Under that interface, the mid pack is cohesive and strong, but this all sits on top of weak sugary snow near the ground.  The snowpack is deep enough for sledding with 60 to 80 cm reported near treeline.

Weather Forecast

Friday looks to be a mix of sun and cloud & the freezing level will likely rise to 1300m in the afternoon.  A storm is moving south of the region Friday evening continuing into Saturday.  The Bighorn will likely see 5 – 10 cm Saturday.  Sunday brings a few flurries with a trace to 5 cm of snow throughout the day.

Prepared by Grant Helgeson

Next Update Thursday February 23, 2012

We have limited field observations from the Bighorn; please let us know what you are seeing out there! Email: forecaster@avalanche.ca

Current Field Report

While the recent mild weather has likely allowed the snowpack to settle and heal a bit, there are still some issues recreationists should be thinking about this weekend.

1.  Wind Slabs

This issue has likely settled down quite a bit, but wind slabs may still be an issue on east facing slopes in wind exposed terrain.  Carefully watch for signs of wind slab; shooting cracks and stiff snow are indicative of this problem.

2.  Cornice Fall

Strong westerly winds have likely created large cornices over the past few weeks.  Forecasted moderate temperatures mean that cornice fall is likely still an issue.  Cornice failure would result in large chunks of dense snow impacting slopes below ridge crest which could trigger a deep slab avalanche.

3.  Deep Persistent Slabs

This region is notorious for harboring shallow weak snow.  A falling chunk of cornice could trigger a deep slab avalanche failing at the ground.

Avalanche Summary

No recent avalanche activity has been reported.  But, that doesn’t mean that they haven’t occurred.  Take a look around when you’re out and about this weekend.  As silly as it sounds, recent avalanche activity is likely your best window into the current avalanche problem.  Take note of where you are seeing avalanches, use that information to make your next move, and then please let us know what you’re seeing out there when you get home.

Snowpack Summary

Thin snowpack areas are likely to have a cohesive (supportive) upper & mid-pack but a weak, sugary lower section. The snowpack is deep enough for sledding with 60 to 80 cm reported near treeline.

Weather Forecast

It looks like dry & mild weather for the foreseeable future as high pressure continues to dominate the weather pattern for much of BC and Alberta.  Daytime temps will remain mild climbing to just below freezing during the day at 1500m, dropping back down to -10 or so overnight.   Winds are expected to be light & variable.

Prepared by Grant Helgeson

Next Update Thursday February 16, 2012

We have limited field observations from the Bighorn; please let us know what you are seeing out there! Email forecaster@avalanche.ca

Current Field Report

Sunshine & Warm Temperatures: The weather has changed to a warm pattern with light wind and lots of sunshine. The arrival of warmth and sun may cause short-term pain with surface layers losing strength, but over the longer term, once temperatures cool or the snow adjusts, the snow comes out stronger.

Keep your eyes open for weakening snow with warmth – either from strong sunshine or high temperatures. I particularly have bowls above ice-climbs in mind; but the same applies if you’re sledding on steep southerly or west facing slopes. Temperature inversions create a pattern such that down in the valley you may be shivering in the shade first thing in the morning; however up near the summits the snow stayed warm overnight and is getting early morning rays. Without overnight freezing the snow in alpine bowls may not recover strength and gradually weaken. The same goes for cornices – they could slowly be weakening and fail.

Wind slabs may linger in pockets on down-wind or cross-loaded terrain; they often look smooth and rounded. They can be firm under foot, and make a hollow drum-like sound beneath you. If you feel the stiffness below, and/ or see shooting cracks from your skis or sled you could be riding a wind slab.

The east side of the region may hold a classic Rocky Mountain snowpack with shallow, weak and facetted (sugary) snow. A deep persistent weakness of depth hoar (large cup shaped crystals that don’t bond well to each other) sits at the base of the pack in thin snowpack areas. If you have stronger layers above (the slab) you may have a problem if you hit a thin spot (rock outcrops, trees, shallow area) or you punch your sled track through the snowpack into the weak basal crystals. This action may trigger a large avalanche across the slope that will release to the ground, bringing the whole snowpack with you. There may be a lower probability for triggering this type of avalanche, but the consequences are often higher because the avalanches are potentially big.

Avalanche Summary

We haven’t received any avalanche reports; however, that doesn’t mean they haven’t occurred, or will occur this week. It’s important to make your own observations in the mountains where you recreate. If I was out ice-climbing I’d watch the weather for both incoming solar-radiation and temperature inversions. You may be shivering in the shadows down low but the snow in the bowl above your climb is warm and weakening.

Snowpack Summary

Last Friday through Sunday was a stormy period, at least along the western edge of the region – how far it spilled over to the east I’m not too sure. Strong SW winds suggest windward slopes are either scoured or hold hard, wind-pressed snow. Lee slopes behind ridges & ribs are where you’re most likely to find pockets of wind slab. Thin snowpack areas are likely to have a cohesive (supportive) upper & mid-pack but a weak, sugary lower section. The snowpack is deep enough for sledding with 60 to 80 cm reported near treeline.

Weather Forecast

A dry and mild pattern is setting up across the west today and is likely to remain for the entire week. A high pressure system means clear skies with lots of sunshine and light southerly winds. I would keep an eye open for temperature inversions. Valley bottoms are likely to see wide temperature swings daily - quickly rising to above freezing during the day and falling overnight. However, at high elevations warm temperatures may prevail day & night. No precipitation is forecast.

Prepared by ilya storm

Next Update Thursday February 09, 2012

We have extremely limited field observations from the Bighorn region.  Please let us know what you are seeing out there! Email forecaster@avalanche.ca

Current Feild Report

It sounds like more and more recreationalists are seeking adventures in the Bighorn Backcountry. Reports suggest the snow quality near treeline and below treeline tends to be quite good for making turns, and the snowpack is supportive to the weight of snowmobiles which provides better riding conditions. I hear most recreationalists are traveling below treeline at this time. I don’t blame you. Conditions sound extremely variable at treeline and into the alpine. With further investigation I see two existing avalanche problems.

Wind slabs

Randy strong to extreme westerly and south-westerly winds have dominated over the past week, and will persist into the upcoming week. These winds continue to form stiff wind slabs in the alpine and at treeline. They are found on opposite slopes, and terrain features. Wind slabs may look smooth and rounded. They can be stiff under foot, and make a hollow drum-like sound beneath you. If feel the stiffness below, and/ or see shooting cracks from your skis or sled you could be riding a wind slab. Wind slabs may be triggered by large loads and even smaller loads if you hit the sweet spot (thin, weak area). If you’re out climbing ice, take note of wind directions and transport while you’re travelling to the climb. Watch for rapid loading, or natural activity that may be occurring in the bowls above your routes.

Deep Persistent Slabs

The Bighorn Backcountry holds a classic Rocky Mountain snowpack which consists of a generally shallow, weak and facetted (sugary) snow. The deep persistent weakness is basal facets and depth hoar (large cup shaped crystals that don’t bond well to each other) that sit at the base of the pack. This weak layer is most easily detected in shallow snowpack areas at tree line and above. A fairly cohesive snowpack sits on top. The problem may arise if you hit a thin spot (rock outcrops, trees, shallow area) or you punch your sled track through the snowpack into the weak basal crystals. This action may trigger a large avalanche across the slope that will release to the ground, bringing the whole snowpack with you. There may be a lower probability of this type of avalanche occurring, but the consequences could be severe.

Avalanche Summary

No avalanches have been reported recently. That doesn’t mean they haven’t occurred, or will occur this week. It’s important to make your own observations within the local mountains you are recreating.

Snowpack Summary

At treeline and above the total snowpack depth is 60-80cms, with possible deeper pockets and slopes where wind deposited snow sits. Windward slopes tend to be scoured, and hold stiff wind pressed snow. Opposite slopes host wind slabs, and a cohesive snowpack overlying weak basal facets and depth hoar. Below treeline open, exposed areas may hold some stiffer wind effected snow. Sheltered areas have up to 10cms of dry, soft snow. Below sits a cohesive snowpack that ranges from 30-40cms deep, with facets and depth hoar at the bottom. Below treeline areas may be offering the best riding conditions.

Weather Forecast

A frontal system will bring cloudy skies and snow amounts near 10cms through the weekend. Alpine temperatures near -16, accompanied by strong SW-W ridgetop winds. Freezing levels will remain at valley bottom. Early next week brings cold, cloudy conditions with ridgetop winds decreasing. Tuesday-Thursday a mix of sun and cloud persist with no forecast precipitation. Temperatures will remain seasonal norms.

Prepared by Shannon Werner

Next Update Thursday February 2nd, 2012

Overview

There is very little information coming out of the region.  If you see something interesting in the field, please let us know about it.  You can send observations to: forecaster@avalanche.ca

Current Situation

It’s been a very cool & dry week as Arctic air moved in from the north switching winds to the NE and dropping the temperature to the bone chilling end of the spectrum.  These Arctic winds are reverse of the normal pattern, so we refer to their affect as “Reverse  Loading.”  What does this mean?  It means that you will likely find stiff wind slabs in unusual locations if you’re out and about this weekend.  The winds have been cranking & I suspect that there are a lot of Hard Slabs in the region, especially on aspects immediately lee to the recent winds, those that face south through west.

The best strategy with this kind of avalanche problem is avoidance; stick to simple wind sheltered terrain below treeline where you will also find the best riding conditions.  Ice climbs threatened by avalanche paths are best given a miss this weekend as there are a few different problem characters in the snowpack that may be pushed to threshold this weekend as a pacific frontal system affects the area.

Avalanche Summary

No avalanches have been reported recently.  They may very well be occurring though.

Snowpack Summary

Cold temperatures have likely been making a weak snowpack weaker.   Watch for rocks and vegetation poking through the snow as they are signs of weakness & these are the kinds of places where you’re likely to trigger a full depth avalanche.

Weather Forecast:

A pacific frontal system will move into the region this weekend bringing 5 – 10 cm with the bulk of the snow coming on Saturday.  This new snow will cover the old wind slabs which may hide the real danger.  Stay alert to how the snow feels under your machine, skis or feet.  If it feels hard, then you’re likely in the realm of the wind slab.  Be alert to what’s above you too.  Avalanches running in the new snow will likely move quickly on the faceted surface which is just one more reason why conservative terrain choices are appropriate for this weekend.

Prepared by Grant Helgeson

Next Update scheduled for Thursday January 26^th, 2012

This week has been dry and warm, with only a skiff of new snow. An icy surface crust has formed with the warm temperatures. This varies in thickness/supportiveness and exists up to roughly 1750m. Below the crust are loose sugary facets.

Temperatures look set to drop towards -20C over the next few days, with cloudy skies and flurries possible. This shouldn’t cause too much immediate change to the snowpack, although I’d expect faceting (weakening) of the snowpack to continue.

Wind Slabs

Snow that has been smashed up and shifted by the wind onto lee slopes may not be bonding well to an icy crust below. In some places, loose sugary snow above the icy crust makes this bond even more tenuous. Wind slabs are likely to exist in the lee of ridges and terrain breaks. Some clues that wind slabs are lurking:

• hollow, drummy sounds
• stiff, breakable snow underfoot
• locally deep snowpack areas near ridges

Travel one at a time if in any doubt.

Persistent Slabs

At the base of the snowpack, loose sugary facets exist. The most likely ways to trigger a deep persistent slab avalanche are:

• From a thin, rocky or sparsely treed part of a slope.
• By putting a very large load on a slope (like a group of snowmobilers or dropping a large cornice).
• By triggering a smaller avalanche (e.g. a wind slab) which in turn triggers the deeper weak layer.

Check out nearby avalanche bulletin regions here and here for more detailed updates which may be relevant.

We have extremely limited field observations from the Bighorn region.  Please let us know what you are seeing out there! Email forecaster@avalanche.ca

Prepared by: Penny Goddard

Next scheduled update: January 19, 2012

It has been very warm in the Bighorn for the past few days. The freezing level has been up to about 2000 metres, and the wind has been very strong during the recent Chinook conditions. We have reports that it was snowing in the alpine during a period of very strong wind on Wednesday.

A ridge of high pressure is forecast Friday and Saturday, this should result in much cooler temperatures and drier conditions. The mountain top temperatures are expected to drop to close to -20.0 on Friday night. The next Pacific system is expected to move in to the region on Sunday and bring light precipitation, warm temperatures, and strong winds. Chinook conditions are likely by Sunday afternoon or Monday morning.

WIND SLAB AVALANCHES

Very strong winds from the West and Southwest have developed hard wind slabs in the alpine and at treeline. These windslabs may be the only areas with enough snow to recreate. Windslabs may be triggered by large loads or by small loads in shallow weak areas adjacent to thicker snowpack areas. These windslabs may sound hollow if you walk or ski on them. If your sled is alternately travelling on top of a firm crust, and then breaking through softer snow, you may be riding on windslab.

PERSISTENT SLABS

The warm weather over the past few days should help to strengthen the facetted base layers. Cold clear weather on Friday and Saturday will slow down the healing process, but the next warm storm forecast for Sunday and Monday will get us headed towards strength again.  I think that it is unlikely that we will see avalanches releasing in the basal facets unless we get quite a bit more snow than the forecast 5-10 cm.  Large triggers, like a group of sledders on the slope at the same time would still be a concern.  Limit your group’s exposure by riding in avalanche terrain one at a time. Avalanches that fail at the ground may be large and destructive.

We have extremely limited field observations from the Bighorn region.  Please let us know what you are seeing out there! Email forecaster@avalanche.ca

Prepared by: Tom Riley

Next scheduled update: January 12, 2012

We have extremely limited field observations from the Bighorn region.  Please let us know what you are seeing out there! Email forecaster@avalanche.ca

Current Avalanche Problems

Wind slabs

New snow combined with strong Southwest winds may have developed new windslabs over the past week. It has been warm during the recent storm, which may create a consolidated slab which is more likely to produce wider propagations. Wind slabs may be found lower on slopes due to the strong winds. The winds may have changed to East during the periods between storms, resulting in reverse loading and/or wind slabs being on several or all aspects. Clues that there is a wind slab problem may include: a hollow, drummy sound or feeling, cracking or ‘stiff’ breakable snow, or actually watching the snow move with the wind from one slope to another.

Persistent slabs

The recent warm and wet weather should start to stengthen the weak base layers. This strengthening occurs due to the added pressure of the new snow load, and the insulating effect of a thicker blanket of snow. That's the good news. The bad news is, that it can take a long time to strengthen and bond a weak base layer. Another cold snap could undo this strengthening. Shallower areas are more suspect to continue to have a weak layer of concern near the ground. If an avalanche does release on the basal weakness, it could be very large and destructive.

There is another wave of snow and wind forecast for Friday morning. A ridge of high pressure should develop by Saturday, and persist for the next few days. The outlook after that is quite variable.

Check out nearby avalanche bulletin regions here and here for more detailed updates which may be relevant.

Prepared by:  Tom Riley

Next scheduled update: January 5, 2012

We have extremely limited field observations from the Bighorn region.  Please let us know what you are seeing out there! Email forecaster@avalanche.ca

Current Avalanche Problems

Wind slabs

 A smattering of new snow arrived during the week with winds which moved loose available snow around. Wind slabs are likely to exist in the lee of ridges and terrain breaks. Winds have been predominantly from the west or south-west, and will continue from this direction over the Christmas weekend. Clues that there is a wind slab problem may include: a hollow, drummy sound or feeling, cracking or ‘stiff’ breakable snow, or actually watching the snow move with the wind from one slope to another.
Ice climbers: Be cautious that wind slabs are not building above your route while you are climbing, as this process can overload snowpack weaknesses rapidly to the point of failure.
Snowmobilers and skiers: If you have your eye on a big, open alpine bowl or face which appears ‘fat’ compared to the nearby terrain, chances are it’s that way because of wind-loading, and wind slabs may be lurking.

Persistent slabs

A weak layer of loose, sugary facets and depth hoar exists near the ground. It’s likely to linger for some time until a significant change in the weather occurs. There are a couple of common ways to trigger a deep weakness. One is from a thin, rocky or sparsely treed snowpack area. The second is by triggering a wind slab or cornice, which could step down to the weakness at the base. If an avalanche does release on the basal weakness, it could be very large and destructive.

The weather forecast looks fairly benign for the Bighorn over the Christmas period, although strong winds are possible as a series of frontal systems pushes onto the West Coast beginning on Saturday.

Check out nearby avalanche bulletin regions here and here for more detailed updates which may be relevant.

Prepared by:  Penny Goddard

Next scheduled update: December 29, 2011

We don’t have a lot of data sources for this area. If this is where you like to play, then drop us a note at forecaster@avalanche.ca

I have been told that there is a weak shallow early season snowpack in the region. It has been very dry and windy over the past week. It has not been extremely cold, but it has not been warm either.

Current Avalanche Problems

Old wind slabs should be pretty stubborn to human triggers by now. We may start to see new soft wind slabs develop in the alpine and at treeline due to new snow and wind. The forecast amounts are un-certain, and the snow might not make it across the divide to the east slope of the Rockies. If we get more snow than forecast, we should watch for new soft slabs that may not bond well to the old wind scoured surface. If you take the time to look at the interface between the new snow and the old crust, watch for signs of surface hoar or surface facets that may have grown during the recent dry period. A weakness at this level may cause wider propagations resulting in larger avalanches. A deep weak layer is reported near the ground. When the snowpack is shallow and exposed to cold temperatures a layer of weak facets or Depth Hoar develops near the ground. This weak layer may take quite a bit of time to strengthen. Usually it takes a combination of new snow and warmer temperatures to “heal” this problem. If we get a heavy load of new snow, it may overload this basal weakness and result in avalanches releasing near the ground. If we continue to get small amounts of new snow, it may be hard to forecast when the load above this weakness reaches critical levels.

There is probably not enough snow to get into a lot of the drainages in the Bighorn by snowmobile. If you are able to get into the high mountains, the steep areas that look like they have enough snow to ride are probably the old wind slabs that are bridging above the weak facets. Skiers should resist the temptation to ski the same type of wind loaded features. Ice climbers should watch for the new soft wind slabs developing that might be easy to trigger from below as they transition between pitches or “top out” into lower angle terrain.

We are heading into a period of change. It may be slow subtle change. If you would like to read more about incremental change please check out our new forecaster blog here

Prepared by:  Tom Riley

Next scheduled update: December 22, 2011

This report is a shot in the dark as I haven’t gotten any actual snowpack observations from the region, but, I’ve got a pretty good feel for what’s happening in adjacent areas.

I suggest reading the Jasper and Banff/Yoho/Kootenay National Park forecasts to get another take on what might be happening in the Bighorn right now. 

There are two main avalanche problems folks need to be aware of this weekend:

Problem # 1, Wind Slabs:

It's been about 10 days since our last significant storm and since that time the snowpack has suffered an unrelenting barrage of wind from around the compass rose. Wind exposed terrain is now a mixed bag of wind effected snow that varies from old hard windslabs to fresh small windslabs and everything in between. To travel safely at & above treeline you need to be able to recognize and avoid these potentially dangerous windslabs. This is the first part of the avalanche problem. Folks with extensive experience and education should be able to manage this hazard effectively.

Problem # 2, (Deep) Persistent Slabs:

Getting a little lower in the snowpack reveals some ugliness. A raincrust sits above large striated facets (sugar snow) on the ground. This is the classic Rockies house of cards setup.  There’s been some significant recent activity involving this layer in the last few days too; A natural size 2.5 avalanche that took out the entire seasons snowpack in K-Country, another natural avalanche with a 400m crown on Mt. Lefroy & a skier triggered size 3 near Lake Louise.  That makes this a very tricky avalanche problem.

Managing the current hazard:

With this setup in place there is a very real chance of triggering a large & destructive avalanche in the region this weekend.  Unfortunately, this issue won’t be going away anytime soon.

The best bet this weekend is to stick to gentle, low consequence terrain.  You’ll also want to avoid slopes that have a thin and therefor weak snowpack.  If you can see rocks & vegetation poking through the snowpack, that’s a good indicator of weak snow.  In my mind, steep rocky terrain is off limits at this time.  If you’re climbing ice, choose climbs that are not exposed to avalanche hazard.  With the recent natural releases we just can’t trust this snowpack. 

Remember, it's only December and our snowpack needs some time to mature before we even start thinking about the bigger more committing terrain.

If you’re out and about this weekend, please let us know what you’re seeing out there.  You can send info to: forecaster@avalanche.ca

Prepared by: Grant Helgeson

Next scheduled update: December 15, 2011

We tend to receive little information from the field in the Bighorn, especially early in the season.

I suggest reading the Jasper and Banff/Yoho/Kootenay National Park forecasts to get a feel for what might be happening in the Bighorn right now. You can also check out the forecaster blog (link in the left panel here) that discusses some ideas for how to approach the mountains after the end of a stormy period. 

As we head into the upcoming weekend with clearing skies, and new snow, it will make venturing out very appealing. Danger ratings from surrounding regions are rated CONSIDERABLE hazard in the alpine. Considerable meaning dangerous avalanche conditions, cautious rout finding, and conservative decision making. I'd like to highlight "Human Triggered Avalanches Likely". Having such limited observations, I feel avalanche conditions are ripe, and waiting for a trigger. It's only the beginning of December, the snowpack is young and we have a full season ahead. It's a good time of year to take an avalanche course, and gather information to help your decision making in the backcountry.

Avalanche Summary

Sunday November 27^th the Rockies reported a significant natural avalanche cycle up to size 3.0. These avalanches have been failing on weak basal facets, running to ground. Current observations are indicating the snowpack to be tightening up with a lull in natural activity. Don’t be fooled, I still suspect human triggered wind slabs likely, which could step down to a full depth release. With the snow depths being highly variable you could also trigger a deep persistent slab from thin, rocky areas on the slope. These full depth avalanches have high consequences.

Snowpack Summary

Snow depths are variable in the Bighorn. A stiff, settling mid pack is sitting on weak basal facets and depth hoar. Sunday's storm combined with strong southwesterly winds created stiff wind slabs on lee slopes. With switching winds from the north you can expect reverse loading, and new wind slab formation on all aspects and unsuspecting slopes. The problem with hard slabs is that they're likely to release above you, when you're low on the slope.  

A highlighted concern for the Bighorn is the variable, heavy slab over a weak basal faceted base. With this clearing trend upon us I bet you'll be able to see evidence of older, large avalanches that occurred on your local mountains. I do suspect that these slopes will be ripe for human, and/or sled triggering especially on northerly aspects where avalanche activity has not occurred. Remember these avalanches are failing on weak facetted (sugary) snow at the bottom of the snowpack, producing full depth avalanches.

Travel Advice

• Avoid shallow areas that may propogate to deeper instabilities
• Avoid paths that have not avalanched recently
• Be cautious if you transition into wind affected areas
• Ice climbers be aware of slopes and local conditions above you

Weather Summary

Light  to moderate precipitation should be short lived and taper off tonight. Ridgetop winds from the NW could reach over 100km/h overnight, then decrease Friday to 60km/h.  A mix of sun and cloud will be evident Friday through Saturday bringing few flurries. Treeline winds will be westerly reaching 70-100km/h tonight, decreasing to 50-60km/h tomorrow. Another high pressure system is building over the province and should persist through the weekend bringing cool (seasonal) temperatures and mainly sunny conditions.

If you've been out in the mountains, send an email to forecaster@avalanche.ca to let us know what you saw. All the data we can get our hands on right now will help.

Prepared by: Shannon Werner

Next scheduled update: December 8, 2011

We have received no information from the Bighorn region yet this season.

I suggest reading the Jasper and Banff/Yoho/Kootenay National Park forecasts to get a feel for what might be happening in the Bighorn right now. Also, I put a post in the forecaster blog (link in the left panel here) that discusses some ideas for how to approach the mountains after the end of a stormy period like the one many regions in western Canada are experiencing at the moment.

It's worth noting that most of the mountains of western Canada have been rated High danger for several days and it looks like that trend will continue for several days yet. In other regions we've seen at least two significant avalanche cycles in the last few days, with slides up to size 3 (big enough to destroy a truck) running to valley bottoms. And I just got a first-hand report of large slides hitting the Banff-Jasper Highway with explosive control operations earlier today.

It looks like the next storms may not be as strong over the eastern Rockies but given what's going on in other areas, I'd suggest this is a time to be very careful in the mountains up there for a few days yet. In fact, my forecasts for other regions have been recommending people stay out of avalanche terrain completely until this storm ends. Playing in non-avalanche terrain is your best bet until this all blows over. Or hunker down and sit the weekend out in front of the TV and watch the Lions take on the Bombers.

If you've been out in the mountains, send an email to forecaster@avalanche.ca to let us know what you saw. All the data we can get our hands on right now will help.

Prepared by: Karl Klassen

Next scheduled update: December 1, 2011