Avalanche Advisory: Monday - Mar 16, 2020

THIS AVALANCHE ADVISORY EXPIRED ON March 17, 2020 @ 7:00 am
Avalanche Advisory published on March 16, 2020 @ 7:00 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Over a foot of new snow fell overnight in some areas, and another foot plus of new snow is possible at higher elevations today, with SE winds blowing at ideal wind slab building speeds.  This will lead to HIGH avalanche danger today above treeline and CONSIDERABLE at treeline and below due to dangerous wind slabs. Storm slabs and loose sloughs will also be of concern.  Be conservative today, and especially avoid traveling on or under steep wind loaded slopes. Natural and human triggered avalanches large enough to injure and bury a person are likely.  Areas around Mammoth and north are more concerning than areas with less new snow further south.  

 

4. High

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

3. Considerable

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

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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Winds have been decreasing overnight and today’s winds will be weaker than yesterday’s, blowing out of the Southeast gusting up to 40mph. These moderate speeds will be much more ideal for more widespread wind slab building.  Much less stripping of exposed slopes will occur today and deposition will occur in more predictable areas.  Watch for denser wind deposited snow just below ridgelines, the sidewalls of gullies, and across slopes around rock outcrops.  Use clues such as blowing snow, cornice formation and shooting cracks to help you avoid areas of dangerous wind deposits. A windslab avalanche today could injure or bury a person.     

 
Avalanche Problem 2: Storm Slab
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In areas sheltered from the wind, storm slabs resulting from the new snowfall overnight and today could be sensitive to a human trigger.  Be wary of steep convexities and slopes that end in a gully or depression.  Do your own localized stability assessments before entering steeper more consequential terrain.  Observations yesterday found storm snow to be bonding well, but today could be a different story.  

 
Avalanche Problem 3: Loose Dry
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As snow continues to fall throughout today, loose dry sloughs resulting from your turns in steep terrain could sweep you off your feet and drag you into obstacles and result in injury or worse especially if the slope ends in a gully or depression.    

 
advisory discussion

Yesterday’s snowfall was less than expected, winds stripped more snow than expected, and danger levels did not reach HIGH as forecasted.  Today’s reality is likely much more dangerous than yesterdays.  

 

And remember, a shallow snowpack with many obstacles existed prior to this new snow. Sharks in the form of rocks, stumps and logs are lurking just below this new snow surface!   

 
Weather and CURRENT CONDITIONS
weather summary

The low pressure system that was expected to more heavily impact our area remained further off coast than expected yesterday, stalling more substantial snow fall until last night and today.  

 

A foot plus of new snow is expected today at higher elevations along the crest, with 4-10” lower down.  Winds will be out of the southeast  with temperatures reaching the mid 20s F around 10,000’.  Snowfall will taper off tonight, and light snow with minimal accumulation is expected for Tuesday.       

 
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 95%. Mostly cloudy. Snow in the evening, then chance of snow after midnight. Snow levels below 7000 feet. Chance of precipitation is 85%. Partly cloudy. Chance of snow through the day. Snow levels below 7000 feet. Chance of precipitation is 30%.
Temperatures: 27 to 35. deg. F. 10 to 16. deg. F. 24 to 32. deg. F.
Mid Slope Winds: Southeast 15 to 25 mph with gusts to 35 mph. Southwest around 15 mph with gusts to 30 mph. Southwest around 15 mph with gusts to 25 mph.
Expected snowfall: 70% probability of 3 to 8 inches. 30% probability of 8 to 12 inches. | SWE = 0.30-0.55 inch. in. 80% probability of 1 to 4 inches. 20% probability of 4 to 8 inches. | SWE = up to 0.20 inch. in. 30% probability up to 1 inch. 70% probability no accumulation. | SWE = less than 0.10 inch. in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 95%. Mostly cloudy. Snow in the evening, then chance of snow after midnight. Snow levels below 7000 feet. Chance of precipitation is 85%. Partly cloudy then becoming mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 30%.
Temperatures: 20 to 26. deg. F. 3 to 8. deg. F. 15 to 23. deg. F.
Ridge Top Winds: Southeast 15 to 30 mph with gusts to 40 mph. Southwest 15 to 20 mph with gusts to 30 mph. Southwest 15 to 25 mph.
Expected snowfall: 70% probability of 5 to 10 inches. 30% probability of 10 to 14 inches. | SWE = up to 0.70 inch. in. 80% probability of 2 to 4 inches. 20% probability of 4 to 8 inches. | SWE = up to 0.30 inch. in. 30% probability up to 1 inch. 70% probability no accumulation. | SWE = less than 0.10 inch. 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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