GALLATIN NATIONAL FOREST AVALANCHE ADVISORY
SUNDAY,  JANUARY 18TH, 1998

Good morning, this is Ron Johnson with your Gallatin National Forest Avalanche
 Advisory issued on Sunday, January 18th at 7:30 AM.  The next advisory will be
 issued tomorrow morning.  Today's advisory is sponsored by the Cooke City Bike
 Shack and the Yellowstone Yurt Hostel.  These advisories do not apply to
 operating ski areas.

Yesterday's quick hitting weather system dropped 2-6 inches of new snow over
 much of southwest Montana.  The exceptions were Big Sky  which got about 8
 inches and  the mountains around Cooke City which got  8-12 inches.  During
 the past 24 hours, ridgetop winds have been mostly from the southwest to west
 at about 10-20 mph with some gusts exceeding 30 mph.  Mountain temperatures
 were mostly in the 20's.  Why am I spending time telling you about past
 weather conditions?  One reason is that the past weather has a direct
 influence on the stability of the snowpack.  The other reason is that, this
 morning, I didn't have access to the Internet and I wasn't able to get any
 weather models or satellite photos which I normally use to develop some sort
 of weather "foreguess".  Luckily, every morning we chat with one one of the
 forecasters at the National Weather Service in Billings.   Here's today's
 forecast......clouds will be increasing as another fast moving Pacific weather
 system approaches our area.  This system should produce another round of snow,
 beginning late tonight or early tomorrow morning.   This system will favor the
 southern mountains with 4-8 inches of new snow possible by noon tomorrow.  The
 northern mountains may get another 2-5 inches.  Mountain temperatures should
 remain mostly in the 20's and ridgetop winds will be from the west to
 southwest at 20-30 mph.

This morning our message machine was loaded with reports from folks that had
 been out cruising in the backcountry.  Near Buck Creek Ridge, which is just
 south of Big Sky, a party triggered and saw the results of several large
 avalanches.  Most of the avalanches were about 2 feet deep  and ran on slope
 angles as low as 30 degrees.  They also mentioned that fractures which
 resulted from the collapsing of the snowpack,  propagated up and across the
 slope for quite a distance.  The Ski Patrol at Big Sky, reported another
 avalanche which was released using explosives.  This avalanche was 3-5 feet
 deep and released on a weak layer which was near the ground.  On Chestnut
 Ridge, which is just southeast of Bozeman, a small avalanche was triggered by
 a skier in an east facing gully.  This slide was about 14 inches deep and was
 on a recently wind loaded  slope that was steeper than 40 degrees.  Finally, a
 party of skiers reported some collapsing of the snowpack and evidence of wind
 loading on slopes near Ross Peak, in the Bridger Range.  Based on these
 observations plus dubious snow stability tests, these folks opted to stick to
 lower angled slopes.   

FOR TODAY,  FOR THE WASHBURN, SOUTHERN GALLATIN AND SOUTHERN MADISON RANGES
 (INCLUDING THE MOUNTAINS AROUND BIG SKY), THE LIONHEAD AREA, AND THE MOUNTAINS
 AROUND COOKE CITY I WOULD CALL THE AVALANCHE DANGER HIGH ON ALL SLOPES STEEPER
 THAN 35 DEGREES.  ON SLOPES BETWEEN 30 AND 35 DEGREES THE AVALANCHE DANGER IS
 CONSIDERABLE .  Remember that these conditions mean that human triggered
 avalanches are likely!

FOR TODAY, FOR THE NORTHERN MADISON, NORTHERN GALLATIN AND BRIDGER RANGES, I
 WOULD CALL THE AVALANCHE DANGER MODERATE ON ALL SLOPES STEEPER THAN 35 DEGREES
 WITH SPECIAL ATTENTION BEING GIVEN TO RECENTLY WIND LOADED SLOPES.  ON ALL
 OTHER SLOPES  I CONSIDER THE AVALANCHE DANGER TO BE MOSTLY LOW.    Remember
 that a moderate avalanche danger means that human triggered avalanches are
 possible!


The Friends of the Avalanche Center are putting on another fund raising slide
 show.  Pat Callis will be sharing slides and stories on his 44 years of
 climbing on Tuesday, January 20th at 7:30pm in the MSU SUB Ballroom A. 
 Admission is $3.  We hope to see you there.

The next advisory will be issued tomorrow morning by about 7:30 AM.   Call us
 with any snowpack or avalanche observations at 587-6984.  You can also log
 onto our internet home page and drop us an e-mail.   This advisory is also
 available on a recorded message at 587-6981 in Bozeman, 646-7912 in West
 Yellowstone, and 838-2341 in Cooke City, and from our home page at
 http://www.gomontana.com/avalanche.  You can also find a bunch of great
 avalanche information at http://www.avalanche.org and http://www.csac.org. 

 

END