THIS AVALANCHE ADVISORY EXPIRED ON February 1, 2020 @ 6:41 am
Avalanche Advisory published on January 31, 2020 @ 6:41 am
Issued by Kevin Davis - Idaho Panhandle Avalanche Center

Selkirks/Cabinets

bottom line

There are multiple weak layers in the uper two feet of the pack right now. The warmer temperatures today and tomorrow will weaken those layers and rain will add weight. Natural avalanches could be possible today and tomorrow. It might be a good weeekend to watch a football game or something.

How to read the advisory

Selkirks/Cabinets

How to read the advisory

There are multiple weak layers in the uper two feet of the pack right now. The warmer temperatures today and tomorrow will weaken those layers and rain will add weight. Natural avalanches could be possible today and tomorrow. It might be a good weeekend to watch a football game or something.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Storm Slab
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The new snow from last night could be adding up to about 4-6 inches. From snow depth readings it is hard to tell but the snow water equivalent is showing 24 hour increases of .5 to .7 which is in the 4-6 inch range. This new snow is falling on a thin surface crust. Watch for the bond at this interface. Also, see how the new snow has effected the weak layers in the upper two feet. You should be able to get the information you need quickly with a quick test pit. These layers will weaken with warming temperatures today and particularly with rain.

Avalanche Problem 2: Wet Slab
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I say a wet slab problem due to the fact that the freezing level is expected to go up to and over 7,000 feet today. There is a good chance that precipitation will be falling as rain up high on all aspects. We did not find a wet slab problem yesterday in the Selkirks but at least the upper portion of the snowpack is going to get wet and heavy. This could create natural wet slab avalanches. Wet slabs are hard to predict and to escape. If you think you might trigger a slide today or Saturday, don't mess with it. You're not likely to walk away. Eric and I saw natural avalanches high on an east aspect that slid naturally on Wednesday. This same layer will be prone to triggering today from the warm, wet weather. This could step down to deeper layers.

advisory discussion

Since the weather, and the snow conditions will not be conducive to pushing the boundaries today and tomorrow I suggest staying off big terrain features while this atmospheric river passes. Temperatures tonight will be above the freezing mark adding to the instability of the snow on Saturday. Conditions could be sloppy. The cold returns Saturday night and this should give us another solid ice crust. It looks like more snow is in the forecast for next week so hopefully we will be back in the powder business soon.

recent observations
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LIke I said, we saw class 2 slides on an east aspect that released on Wednesday in the new snow. They were about 6-10 inches deep and ran the whole length of the slope in steep terrain. Closer to where we were on Flattop we saw shallow releases just below the cornices on a north aspect and a couple cornice breaks. A thin crust had formed over the new snow. Snow from Thursday night is falling on this thin crust. The easy shears in the upper two feet and how they popped out clean had my attention yesterday and it had me thinking that I would not want to be on any big or steep terrain.  Seeing the natural slides confirmed my fears. If you're out today and tomorrow check the snow constantly as the temperature warms and as rain adds weight. Winds will be strong but is not the big factor in the weather. Once the snowpack warms wind transport will be minimal. Pay attention if you do see windloading early on before the pack gets wet. 

Weather and CURRENT CONDITIONS
weather summary 
.SYNOPSIS...
Another round of light valley rain and moderate accumulating
mountain snow will arrive tonight. Temperatures Friday and
Saturday will be well above average with many locations climbing
into the upper 40s and 50s. The passage of a strong cold front
on Saturday may produce strong gusty winds across the Columbia
Basin, Palouse, and West Plains. A cooler weather pattern is
expected next week with a risk more low elevation snow by
Tuesday night into early Wednesday.


&&

.DISCUSSION...
Today and Tonight: The region will still be under the influence
of a shallow ridge allowing the feed of moisture and warm air to
bring widespread rain showers and mountain snow to the above
5000ft for the Cascades to start. An approaching Low toward BC
will bring a warm front through the region on Friday. This will
bring an increase winds for Basin with southerly sustained winds
in the upper teens/low 20s and gusts near 30 MPH. Temperatures
will be unseasonable warm in the upper 40s to low 50s for highs
and the low 40s and upper 30s for lows. The increasing warm air
will increase the midlevel snowpack melt and could lead to some
local rises on the Idaho Panhandles small rivers and creeks. There
is also a small chance of some mud or rock slides in the
Panhandle.

...Strong Winds Possible on Saturday...

Saturday: Winds will major issue for the day. As the low continues
to track through Southern BC and Alberta, it will carry a cold
front through the region during the afternoon. Models still have a
spread on the windspeeds but are still expected to be stronger
than normal for the type of event. Winds will continue to
strengthen through the morning as the gradients near the surface
tighten when the region gets wedged in between the warm and cold
fronts. The winds are expected to be the strongest across the
Basin with sustained into the 20s and low 30s and gusts reaching
into the high 40s MPH. While winds are the main concern, melting
snow in the midlevels and lights showers are expected to bring
rises to small rivers and streams for the region. Once the cold
fronts moves through winds will begin to decline and cooler dry
air will fill in behind it. It will bring a decline in
temperatures to near season normals for this time of yours.
Temperatures are expected to be in the low 50s and upper 40s prior
to frontal passage. The lows overnight will be in the 20s to
upper teens.
Weather observations from the Region
0600 temperature: 31 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: SSW
Average wind speed during the last 24 hours: calm mph
Maximum wind gust in the last 24 hours: mph
New snowfall in the last 24 hours: 4-6 inches
Total snow depth: 122 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Spokane NWS
For 2000 ft. to 4000 ft.
Friday Friday Night Saturday
Weather: Rain. Snow level 4600 feet rising to 7800 feet in the afternoon. Chance of precipitation is 90%. Rain likely. Snow level 6400 feet lowering to 5400 feet after midnight . Increasing clouds, with a temperature rising to around 47 by 1am. Chance of precipitation is 70%. Rain, mainly before 4pm. Snow level 5200 feet lowering to 4600 feet in the afternoon. Chance of precipitation is 90%.
Temperatures: 45 deg. F. 47 deg. F. 46 deg. F.
Wind Direction: SW SW SW
Wind Speed: 7-9mph 13-15mph, gusts to 24 17-20mph, gusts to 32
Expected snowfall: 1/2 in. nil in. <1/2 in.
For 4000 ft. to 6000 ft.
Friday Friday Night Saturday
Weather: Snow before 8am, then rain. Snow level rising to 8000 feet in the afternoon. Chance of precipitation is 100%. Rain likely before 9pm, then rain and snow likely between 9pm and 1am, then a chance of snow after 1am. Snow level 6500 feet lowering to 5900 feet after midnight. Chance of precipitation is 60%. Snow, mainly before 4pm. Temperature rising to near 35 by 9am, then falling to around 29 during the remainder of the day. Chance of precipitation is 90%.
Temperatures: 35 deg. F. 34 deg. F. 35 deg. F.
Wind Direction: SW SW SW
Wind Speed: 14-22mph, gusts to 36. 22-25mph, gusts to 41. 28-31mph, gusts to 49.
Expected snowfall: 2-4 in. <1/2 in. 1-2 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.