Idaho Panhandle Avalanche Center

Backcountry Forecast

Contact:  Kevin Davis (208) 265-6686, Ed Odegaard (208) 245-6209

This message available by calling (208) 765-7323 or toll-free at 1-866-489-8664.

E-mail address:  kgdavis@fs.fed.us, eodegaard@fs.fed.us, mailto:jrolson@fs.fed.us, mailto:dfrigard@fs.fed.us

This is Kevin Davis from the Idaho Panhandle National Forest Avalanche Center.  Today is April 10^th and this is our last update of the season.  The following are some helpful hints to guide you in your spring trips to the mountains.  Our sincere thanks to the Idaho State Parks and Recreation Department for their support of the weekly Avalanche Advisory.  We had another great winter of collaboration on avalanche classes and you can count on us continuing and expanding that in the future.  The IPNF Avalanche Center would also like to thank those that assisted with our avalanche observations; Silver Mountain and Schweitzer Mountain Ski Patrols, and Lookout Pass Ski Area, Selkirk Powder Company, Shep Snow, and everyone who phoned in or emailed us, your assistance is invaluable and we enjoyed working with you and look forward to working with you in the coming winters.

 SPRING TOURING TIPS

Spring is generally a safe time to travel in the mountains but there are some rules to live by.  The safest and best conditions will exist after a good nighttime freeze.  Dig a pit to see how deeply the freeze penetrated.  This will give you an idea of how quickly the snow will become slushy and unstable.  Get on the slopes early before the temperatures get too warm or the sun gets too intense.  Mountain temperatures above 50 degrees should be an indicator that conditions are becoming unstable.  Strong radiation can penetrate deep into the pack and destabilize weak layers.  Steep south facing slopes are affected most rapidly by strong sun.  If you are into the slush up to your boot-tops or you’re laying on the throttle to move its time to get off the slope.  By planning your route to take you to slopes just as they come into the sun and begin to thaw you can enjoy good, safe sliding.  Always be careful around rock outcroppings because they hold heat and weaken the snow for some distance around them.  Rain always weakens the snow pack and this time of year rain can lubricate ice crusts making the overlying layers more prone to slide.  When we do get new snow watch for the type of surface it is bonding to.  New snow on an ice crust that is experiencing melting during the day can be extremely unstable, especially if it is wind-loaded.  In general, new snow will be more sensitive to radiation.  Surface hoar can also be a weak layer in the spring so check under the new snow accumulation to make sure you’re not dealing with that little devil.  Finally, keep track of extended periods of thawing, not only during the day but most importantly overnight.  This will also decrease snow stability.  Night-time temperatures below freezing are a must for good sliding conditions, and safe sliding conditions.  The more nights in a row that freezing conditions occur, the more stable the snow is likely to be.  Freezing conditions will usually accompany clear nights while overcast nights tend to trap heat. 

In the high country the Panhandle is averaging around 80% of average for snowpack and the Clearwater region is slightly higher at about 88% of an average snowpack this year.  The pack may melt out a little earlier this year but we do have enough low elevation snow in most places that will allow us easier access at most trailheads and forest service roads.  On your ventures into the high country remember to respect old terra firma, the brown stuff, that sticks to your boots and tracks on the way up.  Don’t rut up the roads and trails in your truck or ATV trying to get an extra 100 feet.  Park before you get to the muddy sections and try to avoid them as much as possible.  Just like your tracks in the snow, leave no trace.

It sound like the next few days hold snow in the forecast with possibly 3-5 inches of accumulation at the higher elevations.  Winter weather may persist into next week so be thinking about potential slab avalanche conditions with new snow and for a 24 hour period after the storm.  Check to see if the new snow is loading up over a layer of surface hoar.  Eric Morgan was high up in the Selkirks this week and he found powder on a north aspect.  Like we indicated in last weeks advisory, be checking the upper pack above the thick ice crust in the short term as most stability issues will be related to this layer.  Once it is gone, melted out or consolidated, you’ll be looking at deeper crust layers, old surface hoar, and finally the weak base, but I’ll bet you’ll be long into you mountain bike or 4-wheeler by then.  Have a great spring.  We’ll be back next year with the first winter snows.

Avalanche conditions change for better or worse continually. Backcountry travelers should be prepared to assess current conditions for themselves, plan their routes of travel accordingly, and never travel alone. Backcountry travelers can reduce their exposure to avalanche hazards by utilizing timbered trails and ridge routes and by avoiding open and exposed terrain with slope angles of 30 degrees or more. Backcountry travelers should carry the necessary avalanche rescue equipment such as a shovel, avalanche probe or probe ski poles, a rescue beacon and a well-equipped first aid kit.

Have a safe and pleasant weekend.