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GCAC Mission Statement
To support professional and recreational avalanche safety information and education to backcountry travelers, governments, organizations,
businesses and citizens in northwest Montana, in partnership with this United States Forest Service.
NW Montana Glacier Country Avalanche Advisory
This message does not apply to developed ski areas and is brought to you in part by financial grants from GCAC Sponsors
07/01/26_advisory
INTRODUCTION:
This is Tony Willits with the backcountry avalanche advisory issued by
the U.S. Forest Service Glacier Country Avalanche Center at 8:00 AM,
Friday, April 10th for Glacier Park, Flathead and Kootenai National
Forest areas. This will be the last regular advisory issued for
the 2008-2009 season. Only special advisories as warranted, will
be issued for the remainder of the spring.
HAZARD ANALYSIS
Between 5000 and 7500 feet of elevation on steep open slopes (greater
than 30 degrees) the avalanche danger is
currently being rated as CONSIDERABLE during periods of thaw and as
MODERATE during periods of freezing. Below 5000 feet of elevation the
avalanche
danger is currently being rated as LOW.
These danger ratings expire at midnight, Friday, April 10th. The
avalanche hazard is expected remain at the current level through
this weekend.
Because of the general nature of this advisory message, each
backcountry party will always need to make their own time and site
specific avalanche hazard evaluations.
WEATHER ANALYSIS:
Only a trace of new snow since last Friday and since Tuesday
almost no refreezing has occurred, at least anything significant, in
terms of seizing up the surface snowpack.
SNOWPACK ANALYSIS:
Our backcountry observations Thursday were from Noisy Basin on the
Flathead National Forest and Poorman Drainage in the East Cabinets on
the
Kootenai National Forest.
Since Monday thawing and settlement has been ongoing in the regions
snowpack. Wet slab activity was observed in Noisy Basin and as
well from the Kootenai observation. With the sustained warming
this past several days intense roller ball activity led into point
releases and small wet slabs especially on south and west
aspects. A 16 to 18 inch slab pulled out over a melt freeze layer
on an east aspect in Noisy Basin and north aspects with wet slab
activity in Poorman. Ice layers were still bridging softening mid
pack layers and stress tests were revealing those being the best bed
surfaces to slide upon, with less than snappy shears.
AVALANCHE - INSTABILITY DESCRIPTION:
During periods of thaw, between 5,000 and 7,500 ft. elevation we're
rating the avalanche danger
as CONSIDERABLE where unstable slab layers are probable on steep
terrain. Natural avalanches are possible, while human triggered
avalanches are probable. Backcountry travelers should be very cautious
in steeper terrain. Be aware of potentially dangerous areas of unstable
snow.
During periods of freezing, between 5,000 and 7,500 ft. elevation we're
rating the avalanche danger
as MODERATE where unstable slab
layers are possible on steep terrain. Natural avalanches are unlikely,
while human triggered avalanches are possible. Backcountry travelers
should use caution in steeper terrain on all aspects.
Below 5,000' elevation we rate the avalanche danger as LOW.
Snow there is generally stable with only isolated areas of instability.
Natural avalanches are very unlikely, while human triggered avalanches
are unlikely. Backcountry travel is generally safe. Normal caution is
advised.
WEATHER FORECAST & AVALANCHE OUTLOOK:
`
Current Western Montana NWS Backcountry Weather Forecast.
A weak and complex pattern will be present over the region during the
next several days. Snow levels will be quite high during much of
this time, with temperatures near the seasonal average. Shower
activity will reenter the region during Friday afternoon however
no significant snow events are anticipated during the forecast period.
Snowmobilers will need to be extra cautious during periods of thaw to
avoid being a trigger. Climbing on steep terrain with a soft
surface snowpack especially over or near shallow packs (like buried
rock bands) could trigger deeper into the pack even below the mid pack
elevations. The weaker basal layers are still lingering from our
early cold in December and although decomposing from the prominent
sugary crystals they are still a potential to consider especially with
aggressive hill climbing. As an example, was one such second hand
report of a snowmo incident climbing below a cornice and triggering a
slide down to rock and bear grass.
Please note that this avalanche advisory is our best interpretation of
snow pack conditions and National Weather Service forecasts on the day
the advisory is issued. Unanticipated weather changes such as wind, a
marked temperature increase, or precipitation beyond forecast amounts
can increase the avalanche danger. Local variations may also exist.
This message is available via telephone at 257-8402 or on the internet
at www.glacieravalanche.org
DANGER RATING KEY
This advisory is also available on telephone hotline by calling:
Flathead Valley & Outside Montana -- 406-257-8402
Toll-free Within Montana -- 1-800-526-5329
Report your avalanche observations and incidents here
In an effort to improve our service to the public we are attempting
to define the users of this advisory message. Please contact us
with a message listing your backcountry interests. Are you a snowmobiler,
snowboarder, mountaineer, snowshoer, or skier? Also let us know
where you reside.
This advisory best describes conditions at the time of its issuance. As
time passes avalanche and snow conditions may change, sometimes quite rapidly.
Elevation and geographic distinctions used are approximate and a transition
zone between hazards exist. Because of the general nature of the advisory,
each backcountry party will always need to make their own site and time
specific avalanche hazard evaluations.
Thank you for your continuing support of Northwestern Montana's Glacier
Country Avalanche Center.
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