|
|
|
 
|
| 4.9.2010 |
|
|
This is Janet Kellam with the Sawtooth National Forest Avalanche Center with General Snow and Weather Information on Friday, April 9, 2010.
This is our last update, so we have included some avalanche safety tips for spring backcountry sliding and riding. Thank you everyone, for your support this winter.
Upper Elevations:
Recent storms and very strong winds at upper elevations mean that winter-like avalanche conditions are lingering in the high country. Anticipate very different conditions than you find at low elevations and closer to Hailey and Ketchum.
Extra caution is necessary for steep, upper elevation areas, especially if any wind loading or scouring has occurred. Many of these slopes have variable snow cover and a shallower snowpack than you may anticipate. This means a weaker snowpack than typical April conditions. The base of the snowpack this year consists of exceptionally weak depth hoar in a number of locations. Due to this weak base layer we expect a large avalanche cycle in the future at upper elevations when overnight temperatures remain above freezing for several nights.
In many places, the old surface hoar and facet layers are deeply buried and remain dormant, but human triggered and natural avalanches at upper elevations the past few weeks are reminders that we can't forget about them entirely. Careful snowpack evaluation and cautious route-finding are still recommended, we simply don't have a consistently solid spring snowpack in the high country this year.
Low Elevations:
Corn snow and spring conditions have been very good at lower elevations around Ketchum and Hailey due to cold nights and warm days. The only concern here is for when conditions get too soft and mushy late in the day and wet slides become possible. Wet slides become increasingly possible with poor overnight freezes. North of Ketchum and further back in the mountains spring conditions are slow to evolve.
Weather:
check the National Weather Service logo/link on our home page and the Baldy/Titus weather stations
http://www.sawtoothavalanche.com
SPRINGTIME BACKCOUNTRY BASICS:
Timing: Get out early, follow the sun as slopes heat up and be home by early afternoon. There's great snow conditions to be had, but stay heads up in alpine areas and at upper elevations where the snowpack may be more winter-like.
New Snow: New snow will be more sensitive to the sun's heating than older snow. Spring temperatures and sunshine are intense and will initially decrease the stability of any new snowfall on steeper slopes. Watch for newly formed wind slabs poorly bonded to crust layers or perched on top of lighter density snow. It is still important to dig down and see just how well the snow layers are bonded together, how wet or how weak the underlying snowpack may be.
Temperatures: Pay close attention to how deep the overnight freezes penetrate the snowpack. Watch for spring rain events or a dramatic warm-up, either of which lead to increased avalanche danger. Clear skies help to promote a good freeze, clouds create a greenhouse warming effect.
Safe Travel Practices: We continue to recommend safe travel practices such as one person exposed on a slope at a time, closely watch each other, carry avalanche beacons, probes and shovels and be well practiced with them.
SPECIAL THANKS to all our sponsors this season for their generous support!!
The Friends of the Sawtooth Avalanche Center, The City of Ketchum, Blaine County Search and Rescue, the Twin Falls-Shoshone BLM, the Idaho State Department of Parks and Recreation, the Wattis Dumke Foundation, the Sawtooth Society, Mountain Niceness Productions, Smiley Creek Lodge, Idaho Power Company, The Deer Creek Fund in the Idaho Community Foundation, The Elephant's Perch, Woodside Motorsports, and Backwoods Mountain Sports.
And most of all, thanks to all of you for being a part of the Avalanche Center!
See you next season!
Announcements:
We will leave our weather stations up until late spring, check our home page for links. http://www.sawtoothavalanche.com
The National Weather Service will issue daily mountain weather forecasts for our area until April 15th.
http://www.wrh.noaa.gov/pih/avalanche/get_sag.php
Your observations are invaluable! Keep them coming throughout this spring. They help us produce more accurate advisories which in turn helps you. If you get into the backcountry, let us know what you see out there - especially if you see or trigger any avalanches. Call (208)622-0099 or fill out the observer form on our website:
http://www.sawtoothavalanche.com/submit_observation.php
For Idaho road closures check http://511.idaho.gov
For a recording of this advisory, call the Avalanche Hotline - (208)622-8027.
This information only applies to the backcountry and does not apply to highway programs or operating ski areas. Changing conditions and local variations may occur.
|
|
|
|
|
|
