Avalanche Advisory: Sunday - Feb 7, 2021

THIS AVALANCHE ADVISORY EXPIRED ON February 8, 2021 @ 7:00 am
Avalanche Advisory published on February 7, 2021 @ 7:00 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

LOW avalanche danger exists at all elevations.  LOW does not mean NO. Concern still exists for an unlikely but not impossible scenario where a rider could trigger a large persistent slab avalanche in steep complex shady terrain at all elevations. It may be possible to find an old stubborn wind slab to trigger on a steep unsupported slope at upper elevations as well.  

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: Persistent Slab
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  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Sugary faceted snow exists in many places under a robust settled slab of snow from the end of January storm.  While snow-pit test results are still concerning, the snowpack has had time to adjust and it is becoming more and more unlikely that a rider could trigger an avalanche on these buried weak layers.  None-the-less, if an avalanche was triggered it would likely be large and potentially deadly.  E-NE-N-NW slopes where continuous snow existed prior to this last storm are of greatest concern, with potential on W and SE aspects as well. The northern half of the forecast zone is where more continuous old snow existed.  Complex terrain steeper than 35°, an unsupported slope, and a shallow point of snow near rocks is where an isolated trigger point for an avalanche may exist.  What makes this a particularly tricky problem is that there aren’t warning signs, and slope cuts and stomps aren’t safe as they would likely result in the avalanche breaking above you.     

Avalanche Problem 2: Wind Slab
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  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
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    Very Large
    Large
    Small

Strong to Extreme Winds were blowing for several days up until 2 days ago from the SW and then N.  While time has passed to allow new slabs to bond, it may not be impossible to find an area where an old stubborn wind slab could be triggered.  Steep complex terrain above treeline is where you might find a firm panel of unsupported snow that could break loose under you.  

advisory discussion

Sunny skies, warm temperatures and light winds will be with us again today and result in the warming of southerly facing slopes.  Rollerballs will be possible, but should remain small and fairly inconsequential.  If you do notice yourself sinking deep into the snow, it is time to find less steep, or shady terrain,

It is always a tough decision for forecasters to drop the danger rating for persistent slab problems, as a certain degree of uncertainty almost always exists, and a resulting avalanche would likely be large and consequential. While test results are becoming less concerning in some areas, they are still propagating energetically in other areas where they are likely to remain concerning for a long while. Test results are just one piece of the puzzle. It is important for you to put your own thought and analysis in deciding what terrain to ride.

Weather and CURRENT CONDITIONS
weather summary

Another mild day is on tap with sunny skies and temperatures reaching the mid to upper 30s around 10,000’. Relatively light west winds are expected with gusts into the 30mph range. 

A chance of insignificant light flurries is possible for Tuesday, and models are showing a glimmer of hope for the end of the week / weekend for more snow.  

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Sunday Sunday Night Monday
Weather: Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 37 to 45. deg. F. 24 to 30. deg. F. 35 to 43. deg. F.
Mid Slope Winds: West around 15 mph with gusts to 25 mph. West around 15 mph with gusts to 30 mph. Southwest 10 to 20 mph with gusts to 40 mph.
Expected snowfall: No accumulation. | SWE = none. in. No accumulation. | SWE = none. in. No accumulation. | SWE = none. in.
Over 10,000 ft.
Sunday Sunday Night Monday
Weather: Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 30 to 38. deg. F. 22 to 30. deg. F. 27 to 32. deg. F.
Ridge Top Winds: West to northwest 20 to 30 mph with gusts to 40 mph. West 15 to 25 mph. Gusts up to 30 mph increasing to 40 mph after midnight. Southwest 20 to 30 mph with gusts to 50 mph.
Expected snowfall: No accumulation. | SWE = none. in. No accumulation. | SWE = none. in. No accumulation. | SWE = none. 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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