html>
INTRODUCTION:
This is Stan Bones with the backcountry avalanche advisory issued on
Tuesday, February 26, 2008, at 6:00 AM by the U.S. Forest Service
Glacier Country Avalanche Center for the Glacier Park and Flathead and
Kootenai National Forest areas.
HAZARD ANALYSIS
Between 5,000' and 7,500' elevation the avalanche danger is currently
rated MODERATE. Below 5,000' we're rating the avalanche danger LOW.
These danger ratings expire at midnight Tuesday, February 26th. The
outlook is for the avalanche danger to remain near or just slightly
above current levels through Thursday.
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:
This past week Northwestern Montana experienced mostly dry air and
clear skies as high pressure dominated our weather scene. Winds were
generally calm to light during the period. Mountain air temps mostly
bottomed out at night in the teens to low 20's F and then rose during
the day to between 30 and 40 F. It was only on Sunday afternoon and
evening along with Monday morning that we saw any hint of new snowfall,
but even that was scattered and exceptionally light with new amounts
seldom exceeding a couple of inches.
SNOWPACK ANALYSIS:
Our backcountry observations Monday were on Horse Mtn. in the East
Cabinets on the Kootenai, near Bond Lake in the Swan Range SE of Swan
Lake, and in Kimmerly Basin in the southern Whitefish Range NW of
Columbia Falls. In our snowpit investigations we were finding
instability generally confined to the very near surface layers. The
dry weather this past week gave the snowpack a breather and a chance to
gain strength as the bulk of the pack settled and consolidated. Cold
dry nights however created and maintained near surface instability as
surface hoar or near surface facets developed on cold sheltered N'erly
and E'erly aspects. Sun exposure on S and W'erly aspects produced some
surface softening and icing. All these past surface conditions are now
buried under Sunday and Monday's light new snowfall.
AVALANCHE - INSTABILITY DESCRIPTION:
We're currently rating the avalanche danger between the elevations of
5,000 and 7,500' as MODERATE. Unstable slab layers are possible,
particularly on steep, open, wind loaded terrain. Natural avalanches
are unlikely, but human triggered avalanches in isolated pockets remain
possible. Backcountry travelers should use caution, should always
carry and know how ot use avalanche safety equipment, and expose no
more than a single person at a time to any potential danger.
Below 5,000 ft. elevation we're rating the avalanche danger as LOW. A
more shallow snow there is often anchored by vegetation and terrain
features and generally stable with only isolated areas of instability.
Natural avalanches are very unlikely, while human triggered avalanches
are unlikely. Backcountry travel is generally safe, but normal caution
is still advised on any steep, open slope.
WEATHER FORECAST & AVALANCHE OUTLOOK:
The weather forecast is for a dirty high pressure ridge to rebuild over
NW Montana Tuesday. By Wednesday a warm flow of more moist Pacific air
is expected to push into the region giving us our next chance for
precipitation. Temperatures are forecasted to be seasonable, beginning
Tuesday peaking in daylight hours in the mtns. in the mid to upper 30's
and dropping into the 20's at night. By Thursday temps are expected
to cool slightly as a NW flow develops. Orographic lifting is
anticipated to produce light snowfall Tuesday night and into Thursday.
Light S-SW'erly winds Tuesday should gradually increase and shift by
Thursday to more W'erly. We are not anticipating any significant
changes in the current level of avalanche danger, but with some new
snowfall, a bit of wind, combined with the current weak surface snow in
some locations we could see an increase in danger in isolated pockets..
The next regularly scheduled update of this advisory message will be
Friday, February 29th.