Advisory Update April 16

NOT CURRENT ADVISORY

 

Issue Date 8:00 pm – Tuesday April 16

 Each party will need to make their own time- and site-specific avalanche hazard evaluations. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Transition zones between hazards exist.
 
To get updates from the National Weather Service Missoula website consult the forecast discussion for twice daily updates.   The map display allows for the latest forecast by clicking on a location on the map.  As well, one can type in a lat/lon to get to a specific area and get a spot forecast. In adddition a zone forecast can be received by going to this link that may be helpful, Zone Area Forecast for West Glacier/Bob Marshall Region, MT
 
 
 

FAC Avalanche Advisory April 2, 2013

NOT CURRENT ADVISORY

Issue Date

8:00 am – Tuesday April 2

Valid Until

Midnight – Tuesday April 2

Next Update

Friday April 5 (Last Advisory for 2012- 2013)

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

Moderate during periods of thaw. Without overnight temp’s at or below freezing and with sun exposure, a moist more unstable surface snow pack will be present on south and west aspects. Avoid  these aspects during peak warming especially near terrain traps.

Moderate

 

During periods of clear overnight skies and freezing temperatures at upper elevations or on hard shaded northerly aspects.

Low

SITUATION

A warm dry air mass continues to languish over our region with sunny skies.  Sunny skies are expected for today.  Overnight temperatures remained above freezing with exception to Flattop. Temperatures climbed into the mid 50’s yesterday and are expected to be in the 50’s again today. Freezing levels will climb to 6500 to 7000 feet.

Observations Monday were collected from Engle Ridge in the East Cabinets and Noisy Basin in the Northern Swan Range. Warming since Saturday created settlement in the surface snow pack and widespread roller ball activity was observed on all apsects. Point releases near rock outcrops on south and west aspects were observed in Noisy Basin but did not note any recent natural slab activity. Snow pack was nearly isothermic.  Stress tests did not propogate. Glide cracks were observed just above 6000 feet on a west aspect just north of Picnic Notch (see pic below).

DISCUSSION

Temperatures will remain warm through Wednesday as freezing levels climb to 7000′ . Avoid sun exposed aspects during peak warming due to the potential of triggering slab activity during the next few days. Sledders can climb most anything at present. Within the play areas remaining open, avoid south and west aspects during peak warming.  As well avoid any terrain traps on these sun exposed aspects until siginificant refreezing has occurred. Warm moist surface conditions allow sledders to cut down into the mid pack and potentially deeper into some weak basal layers.   A triggered slide could go to the ground resulting in a deep burial, especially around terrain traps, so stay away from this terrain during the midday. 

The avalanche hazard will be Moderate on sun exposed aspects through today.  Hard shaded northern aspects will be Low. Human triggered avalanches are possible.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard should remain at the current level as mild temperatures remain in our region through Thursday. Cornice failures could increase in frequency as temperatures warm and sun exposure intensifies. It is possible that these failures could trigger avalanche activity beneath these cornices. Light showers (like rain) could occur on Wednesday so be prepared to vacate if rain becomes more substantial in the area you are recreating.  

VIDEO

No video available

 

PHOTOS

Glide Crack N of Picnic Notch on West aspect

Noisy 4_1_2013 006

 

april 1Crystal_Grain_Symbols

 

 

FAC Avalanche Advisory March 26, 2013

NOT CURRENT ADVISORY

 

Issue Date

8:00 am – Tuesday March 26

Valid Until

Midnight – Tuesday March 26

Next Update

Thursday March 28

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

 

Moderate

SITUATION

High pressure is lingering over our region resulting in colder overnight temperatures, sunny skies and light SW winds. Temperatures have continued to moderate since Saturday’s single digit and below zero low’s. Temperatures climbed above freezing yesterday and will continue to creep upwards as Thursday approaches.

Observations Monday were collected from Government Mountain in the East Cabinets and Patrol Ridge west of Challenge Cabin in the Granite Creek drainage. An observation from the Mount Shields vicinty was taken by the Park Service on Sunday and posted on Monday. Cold and clear nights have helped develope surface hoar at least from our recent observation locations.  This surface hoar was decomposing rapidly on sun exposed terrain but was observed to be 5 to 7mm on hard shaded aspects.  Melt freeze crusts were noted in the first 100 cms of the snow pack, some more reactive than others. Stability tests identified weak layers over and beneath melt feeze crusts with clean shears but were less than snappy. These stability tests were requiring hard forces to instigate failure.  Our Extended Column Test in the Patrol Ridge pit did not result in propagation. No natural slab activity was noted as we drove through John F Stevens, although did notice a point release on Elk Mountain on an east aspect. 

DISCUSSION

Temperatures above 6000′ today will creep above freezing.  Avoid sun exposed aspects during peak warming due to the potential of triggering slab activity during the next few days.  Cloudy skies are predicted to return by Wednesday but with air temperatures climbing each day.

The avalanche hazard for will be Moderate today. Human triggered avalanches are possible.  Wind loaded terrrain above 6000′ could still be sensitive.  Before skiing or sledding on any lines dig down into the pack to search out weak interfaces over near surface melt freeze crusts. The melt freeze layer(s) vary considerably in strength, depth and interface with changes in elevation and aspect. These melt freeze layers and associated weaknesses, along with wind slabs are the main concerns for today.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard  will rise from the current level as warming temperatures build in our region on Wednesday and Thursday. Cornice failures could increase in frequency as temperatures warm and sun exposure intensifies.  These failures could trigger avalanche activity on near surface melt freeze layers. Squall bands are possible but not likely.  These bands of moisture could produce rain at upper elevations as freezing levels climb Wednesday through Thursday.

VIDEO

No video available

 

PHOTOS

Patrol Ridge 3_25_2013 011

Cornice on Baldhead

 

PatrolCrystal_Grain_Symbols

 

 

FAC Avalanche Advisory March 21, 2013

NOT CURRENT ADVISORY

Issue Date

8:00 am – Thursday March 21

Valid Until

Midnight – Thursday March 21

Next Update

Saturday March 23

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

On all wind loaded terrain the danger rating is:

Considerable

On all other non- wind loaded terrain the danger rating is:

Moderate

SITUATION

 In the last 48 hours temperatures have moderated from the ridge that breifly built on Tuesday and transitioned into our squally day yesterday.  Monday’s at least moderate gains of snow water equivalent (SWE), trickled into light gains of SWE by Tuesday morning. Moderate gains of SWE ranged from .7 to 1.1″ across our region, although the West Cabinets gained a substantial 2.4″, all of these gains were in the last 48 hours.

Observations were taken from the Noisy Basin area on Wedenesday. The observation was taken on an east aspect at 6700′ in a wind loaded area. New snow and light SW winds were observed.  Surface snow that was somewhat dense overlied a supportable melt freeze crust.  Light rain was observed up tp 6000 feet by 1500 as temperatures climbed and light winds persisted. Roller ball activity was widespread there to include east and north aspects. Stress tests revealed no propagation during Extended Column Tests (ECT). No recent signs of avalanche activity were noted at this location.

DISCUSSION

The predicted cold front forecasted to arrive on Wednesday afternoon never materialized and instead brought warming temps into the late afternoon with rising freezing levels. Temperatures have cooled since then with overnight lows into the upper twenties.  Temperatures should be on the cool side with a northwest flow expected to bring us light to moderate gains through Saturday.  Winds are expected to be moderate to strong from the west through today. Expect strong winds in the Glacier NP and Flathead Range areas of our region. These winds will be accompanied with at least light new snow fall. Winds on Friday and Saturday are predicted to be light but a wind shift is expected (N & E).

The avalanche hazard for all wind loaded terrain will be Considerable today. Careful evaluation and site specific investigation required. The interface of the surface melt freeze layer(s) varies with stability as elevation gain is made.  Wind loaded aspects will likely be sensitive and likely to trigger as elevation is gained above 6000′. Moderate to strong W winds with new snow accumulations will be a red flag for our region today.  Avoid ridge top pillows or convexities for the next few days. Colder temperatures will help to solidify thaw conditions from Wednesday but will also maintain weak interfaces that develope  today.

Steep open terrain could be a potential for triggering an avalanche over the melt freeze crusts that have developed in recent days.  Do not assume… check it out.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard should remain at the current level through Friday.  Wind speeds and direction could vary with the influence of local terrain features (situational awareness). Stay tuned for unexpected weather changes.

 

 

VIDEO

No video at this time

 

PHOTOS

 

Noisy Obs 3_20_2013 012

Layering

 

 

FAC Special Avalanche Advisory March 13

NOT CURRENT ADVISORY

 

Issue Date

7:00 am – Wednesday March 13 

Valid Until

Midnight – Wednesday March 13

Next Update

Thursday March 14

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

Considerable

Special Advisory

Warming across our region, with the influence of the southwest flow, has resulted in above freezing temperatures for at least the last 12 hours at all of our recording sites. This period of thaw will continue through tomorrow when temperatures are expected to climb  higher.  In the last 12 hours, gains in snow water equivalent (SWE) have ranged from .2 to 1.0 of SWE, as recorded at the electronic sites.  Until significant  cold temperatures return the avalanche hazard will be elevated. 

DISCUSSION

The general avalanche hazard will remain at CONSIDERABLE across the region. New snow or some decomposed version of new snow overlies a sometimes boot supportable melt freeze crust.  In some areas of our region this surface melt freeze crust is more pronounced than others. This layer or layers will be stressed with new loading and it is possible to expect some natural avalanches to result.  Avoid avalanche runouts and steep opens and stay in sheltered and on low angled terrain (less than 25 degrees). A good example of a safe area is within ski area boundaries.

See the current NWS (backcountry weather forecast).

TREND

The avalanche danger will potentially escalate with new loading that could be variable across our region. This special advisory may be updated at a later time today, otherwise at our next regular advisory on Thursday.  Stay tuned to the weather forecast.  

The next weather influence with significant colder temperatues is not expected to arrive until sometime Saturday.  Do not expect the avalanche hazard to improve until then. 

VIDEO

No video at this time

 
Photo
 
 

FAC Avalanche Advisory March 12

NOT CURRENT ADVISORY

Issue Date

8:00 am – Tuesday March 12

Valid Until

Midnight – Tuesday March 12

Next Update

Thursday March 11

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

Moderate

SITUATION

A broad ridge of high pressure is influencing our region at present with overnight temperatures in the low to mid 20’s.  Monday saw temperatures climb to just above freezing.  Gains in snow water equivalent were light with only .2 to .3 of an inch received late Sunday night. Light winds from the SW were observed on Monday with some light transport occurring.    

Despite this ridge of high pressure our region we will be increasingly influenced with tropical moisture from a southwest flow that will override the ridge that is in place.  Snow levels will rise throughout the day and could push to 6000 feet by tonight.  Thursday is expected to be the warmest day with snow levels possibly climbing between 6000 and 6500 feet.  Although, according to NWS, locations further north and closer to the Canadian Border are more likely to see snow levels somewhat reduced as compared with just 100 miles to the south, where snow levels could reach 7000 feet. If it seems a little “ify” stay tuned to the weather forecast as it will likely be warming and the avalanche hazard will escalate as the warming develops.

Our  observations on Monday were from Allen Peak in the East Cabinets and the Six Mile vicinity in the Swan Range. Both locations had good visibility.  No recent avalanche activity was observed.  On Saturday, a hard slab was triggered by a snowmobiler upon descending from a ridgetop that released a hard slab of 150 yards wide running down abut 200 yards. The fracture was 18″ in depth and was located in the saddle between Bear Mountain and Twin Peaks in the West Cabinets. No injury was reported by the individual nor any damage to the sled.

In the Six Mile vicinity the visibility was good but degenerated a bit by midday but improved again by late afternoon.   No signs of instability were noted as we climbed with a good supportable crust in the morning that degraded with elevation loss upon the descent on sheltered terrain.  Surface sluffs were triggered on a solar aspect especially around rock outcrops.  The wind was light from the SW with no plumes in this observation.

Data from the 6 Mile pit, was taken on an NE aspect at about 6,400 feet in elevation. The extended column test resulted in no fracture propagation in one test and propagation in another. Isolated columns were indicating slow and dirty shear planes with moderate force near the surface and with clean but less than snappy shear planes over melt freeze crusts and ice layers 70 to 100 cms down from the surface, with hard forces.   

DISCUSSION

Forecasted weather predictions for today will bring cloudy skies and the temperatures ranging from freezing to the low 40’s . Tonight temperatures may get just below freezing. Winds are predicted to be moderate from the SW through today shifting from the W by tonight. The forecast is calling for 4 to 6 inches of new throughout today. Expect windloading on north through east aspects at least through late afternoon but may subside with climbing temperatures and more dense snow or rain below 6000 feet. 

The avalanche hazard will remain at MODERATE today.

See the current NWS (backcountry weather forecast).

TREND

Triggered avalanches are possible today. New snow with the potential of wind loading on lee aspects could be sensitive over surface melt freeze crusts. Expect the avalanche hazard to increase after tonight and through Thursday as a rain on snow event is becoming more likely.  The weather forecast is presenting a red flag to be factored in for risk assessments in the next few days.  Be prepared to adjust or cancel your back country travels if the weather forecast continues to develop as predicted. All users will want to avoid any steep open terrain and avalanche runouts if rain developes in the next few days. An example of “avoid” would be to stay at home and watch reruns of Duck Dynasty.  

 

VIDEO

No video at this time

PHOTOS

Pinnacle Ridge

 

Hall_Ball 014

Cross Loaded Easterly Aspect SE from 6 Mile Mountain

 

6_mile

More concerned with buried melt freeze and ice layers down as far as 100 cms especially with predicted warming and the potential for rain on snow

Crystal_Grain_Symbols

FAC Avalanche Advisory March 5, 2013

NOT CURRENT ADVISORY

 

Issue Date

8:00 am – Tuesday March 5 

Valid Until

Midnight – Tuesday March 5

Next Update

Thursday March 7

Because of the general nature of this advisory, each party will need to make their own time- and site-specific avalanche hazard evaluations. This advisory best describes conditions at the time of it’s issuance. As time passes avalanche and snow conditions may change, sometimes quite rapidly. Elevation and geographic distinctions used are approximate and transition zones between hazards exist. This advisory does not apply to developed ski areas.

 

CURRENT DANGER RATING

Moderate

SITUATION

Interesting but not pleasant would be one way of describing this last warming/thaw event over the weekend.  Saturday through early Sunday, saw thaw conditions with temp’s creeping into the mid forties in some locations. Natural avalanches were occuring across the region as temperatures climbed as reported in several obs on Saturday. Temperatures started dropping early Sunday and continued throughout the day as the cold front pushed into our region bringing with it some light to moderate snow accumulations and moderate winds (variable in direction).  The East and West Cabinets, Northern Swan and Mission ranges received less than 1.0″ of snow water equivalent (SWE) from Saturday through Sunday. The northern tier of our region across the Whitefish Divide and Glacier NP gained >1.7″ of SWE.  Temperatures early Monday morning were in the mid teens and dropped into the single digits by Tuesday AM in some locations to drive cold into the surface pack.

Our observations on Monday were from the Pucells and Whitefish Divide. Both locations had good visibility during portions of the day as this last weather disturbance lingered in our region. 

In the Purcells at Big Creek Baldy Mountain the resulting thaw/freeze cycle produced a solid frozen melt freeze crust that supports a sled or skier readily. 

In the Red Meadow vicinity from Whitefish Mountain, during the ascent new snow of 25 to 35 cms overlyed a melt freeze crust that declined in support as elevation was gained. No signs of instability were noted as we climbed.  The extended column test did not propogate. Winds had transported snow that came from the north.   A small fracture was noted on our ascent that released below the ridge east of Whitefish Mountain on a south aspect which likley occurred sometime Sunday. During the descent, surface sluffs (in the surface 20 to 25 cms) were instigated over small steep isolated rolls.

DISCUSSION

Another weather disturbance is predicted to enter our region with rising and falling snow levels from Tuesday and lingering into Thursday morning.  Snow accumulations over this period will range from 6 to 10 inches accompanied by light S/SE winds. Weak interfaces could exist with new storm snow overlying cold affected pre exisitng surface layers.  Be ready to investigate the snow pack as this storm cycle accumulates into Wednesday.  

The avalanche hazard will remain at MODERATE today.

See the current NWS (backcountry weather forecast).

TREND

Expect the avalanche hazard to incremently increase through Wednesday if loading continues to increase as predicted. Triggered avalanches are possible on steep and open terrain especially over convex and ridgetop rolls. Although the recent thaw was wide spread the snow structure varies across our region especially with elevation gain.  Lower elevations may well be “set up” but upper elevation zones 6500 feet and above could have sensitive layers and will need to be investigated as you gain elevation.  

 

VIDEO

No video at this time

PHOTOS

Photo 1…Cascadilla Avalanche on Saturday 3/2/ 2013 by Ted Steiner 

Photo 2…Small Fracture Below Ridge to Whitefish Mountain

Cascadilla Avalanche (2)

Whitefish Mountain_RMV_fractureWhitefish Mountain_RMVCrystal_Grain_Symbols

Southern Whitefish Divide 3/2/2013

Date: 2/3/2012 by Erich Peitzsch

Time:

Location: Southern Whitefish Range

Activity:

 

Snowpack Observations:

Toured around the Southern Whitefish Range near Whitefish Mountain Resort with the Big Mountain Ski Patrol, Inc. Level 2 Avalanche Course the past two days.  We toured and investigated all aspects from 4500 feet to over 6800 feet elevation. Good visibility allowed for us to see small rollerballs and small loose wet avalanche activity from yesterday (3/1). We did not experience any cracking or collapsing throughout the day.Though we were able to trigger small wet loose sluffs late in the day on steep test slopes.  Our snowpits in most locations revealed a layer of graupel mixed with rounding facets about 20-30 cm down from the snow surface.  This layer typically failed with moderate to hard force in compression tests, but did not illustrate the propensity to propagate a fracture (crack) during our fracture propagation tests (like the Extended Column Test and the Propagations Saw Test).  We also found a thin rain crust about 5 cm down from the surface at all elevations. At lower elevations (below 5200 feet) part of the group observed free water moving through the upper portion of the snowpack today.

 

Students and instructors alike were excited when we got to investigate an avalanche crown in the Seven Sisters (Skook Chutes) area (see photo). Again, good visibility today allowed us to see two avalanche crowns in this area from the Ghoulie Point area in the morning. Once we made our way to the crown we speculated the avalanche occurred within the past 4 days. It was fresh enough to see with only a few cm of new snow filling it in thus far. This avalanche failed on a layer of rounding facets on top of a melt-freeze crust about 70 cm down from the snow surface. This slide occurred on a SSW aspect with a slope angle ranging from 35-41 degrees. It was about 60 meters wide and the crown was about 70 cm deep. It was difficult to assess the destructive size as we did not see where the debris terminated down the slope. Not sure if it hit the Canyon Creek road or not as we did not travel on the road in the upper portion of the canyon.

 

Overall, the top 15-25 cm were quite heavy and moist at all elevations leaving a little to be desired in terms of skiing conditions. SW winds increased throughout the day but not a whole lot of snow transport observed.

Cascadilla and Rescue Natural Avalanche Activity

Recent Natural Avalanche Activity

Observation from Cascadilla & Rescue Drainages
3/2/2013
1500

Ted Steiner

Observed recent natural slab avalanche activity that initiated off the northerly aspect of Nyack Mountain in the Middle Fork.  These avalanches appear to have been initiated by a cornice fall and lower avalanche activity appears the have initiated sympathetically. One avalanche terminated in the Cascadilla drainage and the other in the Rescue Creek drainage.  The Cascadilla avalanche occurred on a north aspect and the Rescue Creek avalanche on a north aspect. Both avalanches appear to have been triggered near the ridgeline. 

 Cascadilla Avalanche:

Approximate crown length: 200 meters+ and approximate crown depth: 90 cm+

 Rescue Creek Avalanche:

Approximate crown length: 40 meters and approximate crown depth: 90 cm.

 *Both of these were viewed from US Highway 2- so all measurements are approximate. 

 Photos were attempted but weather moved in and obscured view of the avalanche activity.

.Cascadilla Avalanche and Windloading (2)

Cascadilla Avalanche (2)

Cascadilla Avalanche