THIS AVALANCHE ADVISORY EXPIRED ON April 6, 2019 @ 6:37 am
Avalanche Advisory published on April 5, 2019 @ 6:37 am
Issued by Melissa Hendrickson - Idaho Panhandle Avalanche Center

St. Regis Basin/Silver Valley

bottom line

We are heading into a rain/snow mixed precipitation cycle this weekend. Expect avalanche danger to trend upwards through Saturday and Sunday as we recieve snow at the highest elevations and rain down lower. This is the last regular forecast of the season. 

How to read the advisory

St. Regis Basin/Silver Valley

How to read the advisory

We are heading into a rain/snow mixed precipitation cycle this weekend. Expect avalanche danger to trend upwards through Saturday and Sunday as we recieve snow at the highest elevations and rain down lower. This is the last regular forecast of the season. 

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Loose Wet
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Even though the sun isn't predicted to peak out today, warm temperatures and rain will increase the risk for wet slides. The free water added to the snowpack decreases the strength of the snowpack.  Expect the see wet slide activity increase as the rain increases.  

Avalanche Problem 2: Glide
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Unsure of what a glide crack is?  They are the obvious big "brown frowns" where the entire snowpack starts opening up and sliding downhill.  Rain, direct sun, and warm temperatures cause free water to lubricate the underlying bed surface and cause the glide cracks to open. Watch for large cracks on steep slopes and do your best to avoid lingering around underneath them.  

Avalanche Problem 3: Cornice
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Prolonged warm temperatures and rain continue to weaken cornices. This problem is easy to mitigate: don't hang out under them and continue to give them a wide berth on the ridge tops. Easy peasy. If you see a cleave or a crevasse-like crack where it is breaking away, definitly pay close attention to where you (or your 4 legged friend) is walking.

recent observations

Yesterday we toured to the FAA towers above Lookout Pass.  The morning had a supportive crust on all aspects, which turned into perfect corn skiing by noon.  But yesterday's weather was a little bit different than the predicted weather for today and the weekend.  The instabilities that are created by rain are not always obvious.  Don't commit to avalanche terrain if you are unsure if the snowpack is primed for wet avalanches.  

This is the last official forecast for the Silver Valley for this season.  If a drastic spring storm changes conditions we will post an update then.  In the mean time, practice safe spring avalanche habits.  

-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.

-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 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.

-On your ventures into the high country remember to respect our public lands. 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.

-Backcountry users 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: shovel, avalanche probe, a rescue beacon and a well-equipped first aid kit.

Have a safe spring!  Thanks for a great season. -Melissa

Weather and CURRENT CONDITIONS
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Rain Rain then Rain Likely Chance Rain/Snow then Chance Showers
Temperatures: 52 deg. F. 36 deg. F. 50 deg. F.
Wind Direction: SW SW SW
Wind Speed: 7-9 6-13, G26 10, G22
Expected snowfall: Rain 0.1 in. Rain 0.1 in. 0 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Rain/Snow and Breezy Rain/Snow and Breezy then Snow Likely and Windy Chance Snow Showers and Breezy
Temperatures: 41 deg. F. 32 deg. F. 38 deg. F.
Wind Direction: S SW SW
Wind Speed: 10-18 20-25 21-23
Expected snowfall: 0 in. 1-3 in. <.5 in.
Disclaimer

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.  For a recorded version of the Avalanche Advisory call (208)765-7323.