Information Update for February 20

The backcountry avalanche warning has been allowed to expire but  HIGH AVALANCHE DANGER exists on wind loaded terrain steeper than 30 degrees.

Good morning!  This is Steve Karkanen with an update to the West Central Montana Avalanche Center’s avalanche advisory issued on February 20.  This information is the responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight.

The high winds we experienced since Tuesday have diminished, temperatures are cooling and snowfall amounts have tapered off.  This morning,  SNOTEL data shows that most sites received around .50″ of SWE or about 5-6 inches of new snow.  Mountain temperatures are now in the high teens and low twenties and the wind speeds are down to a tolerable 11-15 mph.

The main avalanche problem to be looking for now are wind slabs and heavily drifted areas caused by the 50-60 mph winds since Tuesday.

The avalanche danger is HIGH  on wind loaded terrain steeper than 30 degrees. Very dangerous avalanche conditions exist.  Natural avalanches are likely, human triggered avalanches are very likely.  Travel in avalanche terrain is not recommended.  Any open terrain that has been recently wind loaded is dangerous.  Avoid avalanche paths and their run out zones.

On other terrain steeper than 30 degrees the avalanche danger is CONSIDERABLE. Natural avalanches are possible, human triggered avalanche are probable.  Storm snow slabs are the secondary avalanche concern as there are now several different storm snow/old snow surface interfaces that have not had adequate time to bond and adjust to this weeks heavy load.  The more deeply buried faceted layer that formed in late January is reactive in many of our stability tests.  The close call in the Spruce Creek area is a good example of this potential.

The bottom line is that you can’t trust this snowpack right now.

This includes areas above 5000 feet in the Bitterroot mountains from Lost Trail Pass to Hoodoo Pass, the Rattlesnake mountains north of Missoula and the southern Swan and Mission Mountains on Lolo National Forest Lands near Seeley Lake, MT.

Our field observers and avalanche specialists will be out in force today and I will issue an updated advisory tomorrow (Friday) morning by 0700.  Your information is vital to the strength of this program as well. So if you get out and see avalanche activity or simply excellent conditions, let us know.