Flathead Avalanche Center

Whitefish Range/Flathead Range 13,14 April 2013

Seth — Mon, 15 Apr 2013 19:16:35 +0000

From: Joe Grabowski
Date: April 13 & 14, 2013
Time: Middle of the day
Location: Whitefish Range & Flathead Range
Activity: Skiing

Snowpack Observations:
Ir is worthwhile to note that although the skiing is good the stability is not good. I toured the southern Whitefish Range on Saturday and the Flathead Range on Sunday. I am finding poor bonding between the storm snow (8″) and the sliding surface. Easy but resistant shears. On Sunday the top layer of the storm snow was becoming heavy and therefore inverted.

Advisory Update April 16

Tony — Mon, 15 Apr 2013 19:02:04 +0000

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 for April 5, 2013

Seth — Fri, 05 Apr 2013 13:58:35 +0000

NOT CURRENT ADVISORY

Issue Date

8:00 am – Friday April 5

Valid Until

Midnight – Friday April 5

Next Update

This is the Last scheduled Advisory for 2012- 2013 Additional advisories will be posted if conditions warrant

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 during periods of rain on steep slopes until refreeze occurs.

After a refreeze has occurred

SITUATION

It has been over a week since most areas have seen freezing temperatures. A system moved in Thursday night that started to bring precipitation in the form of rain to all elevations. Gains overnight have ranged from .07 to .4 inches. This precipitation is expected to continue through the weekend with snow levels slowly dropping to around 3000 feet by Saturday night.

Observations Wednesday and Thursday were from Kimmerly Basin in the Whitefish Range and the Middle Fork. The lack of any substantial freezing for over a week, warm temperatures and sunny skies has created settlement and warmed the snowpack. A wet slab avalanche and a glide crack failure were reported up the Middle Fork on Southeast aspects and numerous loose wet avalanches have been observed in other areas. Some of the loose wet avalanches were triggered by cornices that are either calving or completely collapsing. Stress tests did not propagate. More glide cracks are being observed throughout the area. Backcountry users will need to make site and time specific evaluations for the areas they are in.

DISCUSSION

Precipitation is forecasted to continue through the weekend with temperatures cooling through the period. This will drop snow levels to near the valley floors by Saturday night and Sunday. Precipitation amounts, in the form of rain in most places, are expected to be in the neighborhood of a 1/4 inch on Friday. This rain, in addition to the rain received Thursday night, will further weaken the bonds in the snowpack. Be cautious and suspicious around any cornices and glide cracks. Avoid steep slopes and terrain traps until refreezing occurs and especially during times of substantial rainfall. Slides have the potential to go to the ground, especially in areas of shallow snowpack. Potential problems include Loose Wet Avalanches, Wet Slab Avalanches and Cornice Falls.

The avalanche hazard will be Considerable during times or rainfall through today. Natural avalanches are possible and human triggered avalanches are likely. During times of refreeze and on moderate angle slopes, the hazard will be Moderate. Human triggered avalanches are possible.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard should decrease through the weekend as rain turns to snow at most elevations and refreeze occurs. Additional snow fall on the already settled snowpack should have less of an impact, especially with freezing temperatures. Look for rain and warm temperatures to decrease stability and freezing temperatures to increase stability.

This is the last, scheduled advisory for the 2012/2013 season. We will be monitoring conditions and update the advisory as conditions warrant. As always, backcountry users will need to make site specific evaluations for the areas they are in. After this weekend, the general avalanche danger should be low, but there will still be specific areas of higher hazard at times.

VIDEO

No video available

PHOTOS

Cornice calving triggering a WL-NC-R3/D2-O (Wet Loose- Natural (cornice) triggered- ran most of the slide path/ could bury or injure a person- on old snow) Kimmerly Basin 4/4/13

Glide Cracks, Kimmerly Basin 4/4/13

Cornice calving. Kimmerly Basin 4/4/13

Middle Fork 4/4/13

Seth — Thu, 04 Apr 2013 21:23:26 +0000

Recent wet slab release observed at 1420 today (4/4/2013) on a south/ southwest aspect… SZ approximately 6,200 feet elevation and terminus at approximately 5,000…

FAC Avalanche Advisory April 2, 2013

Tony — Tue, 02 Apr 2013 10:52:09 +0000

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)

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.

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

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

FAC Avalanche Advisory for 3/30/2013

Seth — Sat, 30 Mar 2013 13:56:19 +0000

NOT CURRENT ADVISORY

Issue Date

8:00 am – Saturday March 30

Valid Until

Midnight – Saturday March 30

Next Update

Tuesday April 2

CURRENT DANGER RATING

SITUATION

The last couple of days have been relatively warm with sporadic bursts of precipitation, mostly in the form of rain. Snow Water Equivalent (SWE) gains have been light, between 0 to .3 inches. Temperatures have been reaching into the 40′s at higher elevation and 50′s at lower elevations and only reaching below freezing briefly, if at all.

Observations Thursday and Friday were collected from the East Cabinets and Noisy Basin (see snow profile below). There are numerous melt/freeze crusts located in the upper 100 cm of the snow pack. Those crusts are currently adding strength to the snow pack, but that strength will deteriorate as warm temperatures and solar radiation continue to invade the snow pack and erode those bonds. Stability tests showed that some of those melt freeze crusts also have weak layers of graupel or facets above or below them, but required moderate to hard force to cause failures. No natural avalanche activity was observed. In all but the highest elevations, temperatures have stayed above freezing the last couple of nights. This is allowing the warmer air to penetrate further into the snowpack and weaken some of the bonds that have been created. This is predicted to continue through the near future.

DISCUSSION

Bring on the Sun! The National Weather Service is forecasting sunny skies and temperatures into the high 40′s and 50′s Saturday through Tuesday. The lack of a meaningful re-freeze at night is of particular concern as it will continue to allow warmer air to push further into the snowpack. No precipitation and light winds are forecasted. .

The avalanche hazard will be Moderate Saturday. Human triggered avalanches are possible. Wet Snow Avalanches or Wet Slab Avalanches are the most likely problems. Avoid slopes that are being impacted by the sun and warm temperatures, especially during the warmest parts of the day. Without freezing temperatures, the snowpack won’t be recovering strength at night. As the warmth and sun penetrate further into the snowpack, bonds will be eroded, weakening some of the strength offered by the melt/freeze layers and increasing the risk of a human triggering a slab avalanche. Cornice Falls will also offer concern to backcountry travelers. The sustained warm temperatures will continue to weaken the cornices. Avoid areas below cornices.

With the spring weather and good travel conditions, backcountry users and especially snowmobilers will be able to reach into the upper elevations and start zones of avalanche paths. These areas could be sensitive as the snowpack warms, so use caution or back off until a strong refreeze occurs so as to avoid triggering an avalanche into potentially weak basal layers.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard will be similar if not a little higher as the warm temperatures and sunshine continue to warm the snowpack. Concerns will continue to be the same Loose Wet Avalanches, Wet Slab Avalanches and Cornice Falls. Don’t let the spring weather lull you into dangerous situations.

VIDEO

No video at this time

PHOTOS

Skiumah 3/26/13

Seth — Fri, 29 Mar 2013 13:33:40 +0000

From: gary Ludwig
Date: 3/26/2013
Time: 1:00pm
Location: Skiumah/Great Bear/Deerlick basins
Activity: Skiing

Snowpack Observations:
Snowpack observations: Skied the north face Great Bear Ridge and Triangle Peak on Tuesday. Despite the recent warm-up, the north aspects were still cold with 1-2 feet of great powder snow all the way to the bottom. There was a firm sun/rain crust underneath, but we did not notice its presence until about 300 feet above Deerlick creek. The powder above 6000 feet did show some minor surface sloughing, but did not run far or propagate for any significant distance. A surface hoar layer with 2-3mm crystals was present on the south and west facing slopes beginning at elevation 6500 feet. All south and west facing slopes below 6500 feet were hard packed. The only recent avalanche activity observed was a few point releases on steeper slopes above Skiumah lake.

FAC Avalanche Advisory for March 28, 2013

Joy — Thu, 28 Mar 2013 11:50:16 +0000

NOT CURRENT ADVISORY

Issue Date

8:00 am – Thursday March 28

Valid Until

Midnight – Thursday March 28

Next Update

Saturday March 30

CURRENT DANGER RATING

SITUATION

Warm temperatures and sunny skies has been the norm for the last couple of days. Currently the temperature is 33 degrees and the winds are calm. The cloudy skies are threatening to bring us some scattered light rain with the snow level being around 5,500 feet today. The forecast is calling for light rain showers mostly South of HWY 90 but our region might get a few drops and in the higher elevations we may see 1-2 inches of new snow. Overnight temperatures were lingering from just below freezing to just above freezing across our region with no new snow and trace amounts of SWE(snow water equivalant).

Observations Wednesday were collected in Kimmerly Basin area at 6,814 feet on an East aspect. Surface hoar was observed in most areas within the basin but was quickly being affected by the warm, sunny, blue sky early afternoon. This 2-3 mm surface hoar was being sheltered in shaded areas. Melt freeze crusts were noted in the first 100 cms of the snow pack. The melt freeze crust about 10 cm down from the top supported us as we skinned up and skied down in the early afternoon, this was probably not the case by late afternoon as the warm temperatures wore on. Stability tests identified weak layers over and beneath melt feeze crusts with Quality 2 and 3 shears. These stability tests were requiring hard to very hard forces to produce failures along weak interfaces, such as a graupel/rounding faceted layer on top of a melt freeze layer about 50 cm down from the top . Our extended column tests resulted with no propagation. No natural avalanche activity was observed and no new cornice failures had taken place, however as the day warmed up the cornices around the basin were producing small roller balls resulting in small point releases.

DISCUSSION

Temperatures are forecasted to be in the high 30′s to low 50′s today with light winds and mostly cloudy skies. Tonight the temperatures will hover around freezing and winds will remain light.

The avalanche hazard will be Moderate today. During peak warming throughout the day avoid sun exposed aspects due to the potential of triggering a slide and avoid traveling under cornices as these may fail due to higher temperatures. Human triggered avalanches are possible. Timing is of the essence here. Ski early when bonds between grains have regained their strength due to overnight temperatures. As the day wears on and temperatures climb remember bonds are being eroded causing weakness which could be just the right mix to trigger an avalanche as you drop onto a slope. As surface layers weaken slab avalanches may occur and with deeper instabilities present deep slab avalanches could be triggered especially with springtime warming.

See the current NWS (backcountry weather forecast)

TREND

The avalanche hazard will rise from the current level as warming temperatures build in our region into the weekend. Overnight freezing periods are shortening and daytime warming periods are increasing, instabilities will become more apparent as springtime thaw continues. Cornice failures could increase in frequency as temperatures warm. These failures could trigger avalanche activity on near surface melt freeze layers.

VIDEO

No video at this time

PHOTOS

Shed 9, Middle Fork 3/26/13

Seth — Wed, 27 Mar 2013 15:40:03 +0000

BNSF RAILWAY AVALANCHE SAFETY

VOLUNTARY FIELD OBSERVATIONS

Steiner

3/26/13

Shed 9 SZ

GENERAL INFORMATION:

Toured up Shed 7 West avalanche path to the Shed 7 ridge and then west into the Shed 9 Starting zone. Ascent conditions were fair and travel was easy- with the use of ski crampons. Descent was fair as surface snow had warmed to moist/ wet consistency. Surface roughness increasing substantially at lower elevations. Vegetative and terrain hazards becoming more prevalent at snowpack surface.

WEATHER OBSERVATIONS: Mostly clear skies today with a few scattered clouds. Light west winds. Air Ts on Canyon floor were in the lower 20s F in the AM and warmed into the mid-30s F by afternoon. Air Ts at approximately 6000 feet during the afternoon hovered around 32 F. Solar input significant today…SNOWPACK OBSERVATIONS: Full profile conducted in the starting zone of Shed 9 on a south/ southeast aspect (140 degrees) 30 degree slope at an elevation of 6800 feet (6800’). Snowpack depth 116 cm and moist in upper most layer and dry for remainder of snowpack. Significant Temperature gradient existed in the upper 16 cm of the snowpack.Upper and mid snowpack at this location was relatively supportive and consisted of rounded grains, a 10 cm melt/freeze crust, and decomposing facets- beneath the MF crust. No significant stability test results on these layers.Greatest concern at this location is related to depth hoar found in the lower 47 cm of this profile. This layer is 47 cm in height, 4F+ in hardness, comprised of 3mm depth hoar and is adjacent to a P hard ice crust/ lens. This layer/ layer interface was not reactive in ECT tests but failed with hard force Q2 shears in CT stability tests.*Please refer to attached Snow Profile.Similar to last week’s observation in the Shed 5 starting zone (March 19th, 2013) we feel the mid-pack at this location appears to be providing supportive structure to the snowpack.

AVALANCHE OBSERVATIONS:

One relatively small soft slab avalanche that had previously released was observed in the starting zone of Shed 9. Debris associated with this slab terminated in the upper 1/3 of the Shed 9 SZ.

BNSF AVALANCHE SAFETY FIELD OBSERVATIONS SUBMITTED TO FLATHEAD AVALANCHE CENTER AND GLACIER NATIONAL PARK ARE BEING PROVIDEDED IN ACCORDANCE WITH THE TERMS AND CONDITIONS SPECIFIED GLACIER NATIONAL PARK SPECIAL USE PERMIT.

THESE OBSERVATIONS REPRESENT SITE SPECIFIC INFORMATION INTENDED FOR THE BNSF AVALANCHE SAFETY PROGRAM AND IN NO WAY ARE TO BE CONSTRUED AS A PUBLIC/ RECREATION AVALANCHE FORECAST.

Shed 9 Start Zone 3_26_13

FAC Avalanche Advisory March 26, 2013

Tony — Tue, 26 Mar 2013 11:11:43 +0000

NOT CURRENT ADVISORY

Issue Date

8:00 am – Tuesday March 26

Valid Until

Midnight – Tuesday March 26

Next Update

Thursday March 28

CURRENT DANGER RATING

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

Cornice on Baldhead