Avalanche Advisory: Friday - Jan 17, 2020

THIS AVALANCHE ADVISORY EXPIRED ON January 18, 2020 @ 6:08 am
Avalanche Advisory published on January 17, 2020 @ 6:08 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

12”+ of new snow fell last evening with sustained extreme winds out of the SW.  Winds will continue to transport snow into dangerous wind slabs throughout today resulting in HIGH avalanche danger at tree line and above and CONSIDERABLE below tree line.  Sensitive storm slabs in sheltered terrain will contribute to the avalanche concern. Travel in avalanche terrain is not recommended.    

 

4. High

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Above Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

4. High

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Near Treeline
Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1: Wind Slab
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6-12” of new snow was recorded yesterday evening, with more likely falling at higher elevations.  Extreme winds out of the SW exceeded 100mph over ridge tops, and are forecasted to continue at very strong levels today.  Even though the snow has stopped falling, sustained winds will continue to build dangerous wind slabs throughout today on leeward terrain. NW-N-NE-E-SE-S facing slopes will be of most concern. Remember that wind can deposit snow much much faster than it can fall from the sky.  Underlying loose facet layers could lead to the potential of a smaller avalanche stepping down and becoming larger than expected. Natural avalanches will be likely and human triggered avalanches very likely, and will certainly be large enough to burry a person.  Avoid traveling on or under slopes that are potentially wind loaded.

 
Avalanche Problem 2: Storm Slab
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Up to a foot of new low density snow fell yesterday evening at mid-elevations on top of old snow surfaces that range from loose faceted grains to firm and slick.  Cold temperatures will make bonding slow. Human triggered avalanches will be likely in steep terrain sheltered from the wind.  Watch for signs such as shooting cracks and avoid steep convexities and confined gully features where even a loose snow avalanche could be consequential.           

 
recent observations

Weather Station - New snowfall amounts (mostly all falling between 4-8pm yesterday evening)

-Mammoth - Sesame (9014'): 6.5" (0.65"SWE)

-Mammoth Pass (9972'): 12"

-June Mtn (9148'): 11" (0.5" SWE)

-Tioga Pass (9972'): 9"

-Agnew Pass (9355'): 9"

-Rock Creek (9600'): 11"

-Sawmill above South Lake (11919'): 8"

Field Observations

-1/16 - Mammoth - Red Cone: Late storm onset, pre-storm snowpack.

-1/15 - June - Chicken Wing: Snowpack and facets.

-1/15 - VA Lakes: Faceted underlying snow.

-1/15 - Mammoth - Smugglers: Prestorm snowpack.

-1/15 - Mammoth - Sherwins: Prestorm snow.
 

Weather and CURRENT CONDITIONS
weather summary

High pressure settles in thru the weekend.  Expect partly cloudy skies today, highs in the upper 20s around 10,000’, and very strong SW to W winds decreasing in the afternoon. 

A chance for another small storm exists for Tuesday.   

 
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy. Partly cloudy then becoming mostly cloudy. Mostly cloudy then becoming partly cloudy.
Temperatures: 27 to 33. deg. F. 16 to 21. deg. F. 38 to 44. deg. F.
Mid Slope Winds: Southwest around 15 mph with gusts to 40 mph in the morning becoming light. Southwest around 15 mph with gusts to 35 mph. Southwest around 15 mph with gusts to 35 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: Partly cloudy. Partly cloudy then becoming mostly cloudy. Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet.
Temperatures: 21 to 29. deg. F. 12 to 17. deg. F. 31 to 39. deg. F.
Ridge Top Winds: West 20 to 30 mph with gusts to 50 mph decreasing to 15 to 20 mph with gusts to 35 mph in the afternoon. Southwest 15 to 30 mph. Gusts up to 35 mph increasing to 45 mph after midnight. Southwest 15 to 30 mph with gusts to 40 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer
This Avalanche Advisory is designed to generally describe avalanche conditions where local variations always occur. This product only applies to backcountry areas located outside established ski area boundaries. The information in this Avalanche Advisory is provided by the Eastern Sierra Avalanche Center, who is solely responsible for its content.

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