Winds picked up during the last 24 hours with gusts hitting 26 mph. Wind slabs and wind loaded slopes should be anticipated and avoided today. Look for new windslabs near ridgetops on on micro terrain features like gullies or other areas that can collect wind blown snow. The possibility of a shallow wind slab stepping down into the layer of buried surface hoar mid pack is also likely, if you trigger a shallow wind slab it could turn into a much bigger problem very quickly. The prime northerly slopes that are harboring the persistent weak layers are also the slopes that are most likely to have freshly deposited wind slabs today. Obvious signs of windslabs are recent drifting, wind deposited pillows or a sudden change in the consistency of the snowpack from soft to firm. Shooting cracks produced by your skis or sled are also a sure sign you are on a windslab.
This week's storm just added up to an inch of Snow Water Equivalent or SWE in 24 hours in some areas throughout the West Central. Temperatures went up during the storm as well with warmer temperatures forecasted today. Those factors added to the effects of the wind just added a significant load and strain for a shallow, early season snowpack, especially one harboring multiple persistent weak layers. Buried surface hoar from early December is widely distributed throughout the area and can be found 12-18 inches down in the snowpack. A layer of sugary depth hoar is also lingering near the ground on any slope that held early season snow. Both of these layers are going to be closer to the tipping point with the added weight of new and wind blown snow and are more likely to produce human triggered avalanches over the next few days than they were prior to the storm. Surface hoar problems are also much more likely to propagate over larger distances when they are widely distributed. This means that you could remotely trigger a slide or that a slide you trigger could spread out quickly.
Thanks to the Friends of the Payette Avalanche Center for a great season opener last night. Big thanks also to Broken Horn Brewery for hosting us and providing great food and drinks. If you haven't checked it out already, see our FB page or the education page on the FPAC site for a list of all of the upcoming classes. Get some knowledge and Know Before You Go.
|0600 temperature:||26 deg. F.|
|Max. temperature in the last 24 hours:||26 deg. F.|
|Average wind direction during the last 24 hours:||SW|
|Average wind speed during the last 24 hours:||8 mph|
|Maximum wind gust in the last 24 hours:||23 mph|
|New snowfall in the last 24 hours:||NA inches|
|Total snow depth:||NA inches|
SHORT TERM...Today through Monday...Gusty winds noted across the
forecast area this morning, with a few locations in eastern Oregon
also reporting fog. Generally dry conditions expected this morning
through Sunday afternoon with mild temperatures. An approaching
trough on Sunday will spread showers across eastern Oregon on
Sunday night, with activity spreading into southwestern Idaho by
Monday morning. Most activity is currently anticipated to be
confined to the higher elevations, but conditions will continue to
be monitored as this upcoming system approaches.
.LONG TERM...Monday night through Thursday...Models are all fairly
similar in showing some sort of weak split trough over the region
through a majority of the week. Most of the energy that moves
towards the west coast remains well south of the forecast area. This
pattern would give the region a slight threat of snow showers each
day with little in the way of snow accumulations. Temperatures for
the period should be near or slightly above normal.
This avalanche advisory is provided through a partnership between the Payette National Forest and the Payette Avalanche Center. This advisory covers the West Central Mountains between Hard Butte on the north and Council Mountain on the south. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires at midnight on the posted day unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.