Avalanche Advisory: Wednesday - Jan 6, 2021

THIS AVALANCHE ADVISORY EXPIRED ON January 7, 2021 @ 6:42 am
Avalanche Advisory published on January 6, 2021 @ 6:42 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

While avalanche danger has dropped to LOW today, small Isolated wind slabs that could be sensitive to a human trigger are still a concern. Be wary of dense snow deposits in steep terrain, particularly on a convex roll or where the slope is unsupported above a cliff particularly on NW to NE to SE aspects.   

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

1-3” of dense snow fell on Monday accompanied by extreme SW winds at all elevations.  Avalanche activity was reported in the Sherwins yesterday morning, likely occurring naturally Monday night from active wind-loading.  Yesterday was calm and mild, allowing the bulk of the potentially concerning wind slabs to bond. Last night SW winds ramped up to moderate levels again, however with minimal loose snow available for transport, fresh wind slab formation will be quite limited. All that being said, keep on the lookout for small isolated areas where a person could trigger an older stubborn wind slab or a fresher more sensitive wind slab. These are most likely to be found below ridgelines and the sidewalls of gullies on NW to NE to SE aspect, but due to the extreme winds on Monday, could be found in sheltered terrain as well. Steep unsupported slopes and convex rolls are more likely trigger points.  Do your own quick hand-pit tests to see how easily dense surface snow pops off.  Remember even a small slide can be consequential with our obstacle-ridden thin snow pack.   

advisory discussion

Our thin snowpack still has weak snow buried in many places. Although pit-tests continue to show that it has potential to fail (with increasingly hard force), an actual persistent slab avalanche is very unlikely without a significant new load of snow to offset the snowpack’s balance.  That being said, it is not impossible that an isolated wind-loaded area exists where a buried weak layer could be triggered. It's always important to practice safe travel protocols just in case, such as exposing one person at a time to steep terrain. We will keep monitoring these layers, with hopes that a new heavy load will come before too long! 

recent observations
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-1/5 – Mammoth – Sherwins: Avalanche activity.

-1/5 – Mammoth Lakes Basin – Red Cone Ridge to Sherwins: Wind effects.

-1/4 – VA Lakes - Red Lake Bowl: light snowfall, strong winds, dense snow deposits

-1/4 – VA Lakes – Red Lake Bowl: Small dense windslabs 2-6” thick

-1/4 – Mammoth – Sherwins: light snowfall, strong winds, thin dense snow deposits

Weather and CURRENT CONDITIONS
weather summary

Partly cloudy skies are expected today with mild temperatures reaching the mid 30s around 10,000’, and moderate SW winds gusting into the 30s at mid and upper elevations.  Weak storm systems move thru Northern California today and Thursday, unfortunately our region will stay dry with only increased winds and clouds.  High pressure ridging sets in over the weekend, and looks to remain in place at least thru mid January keeping conditions mild and dry. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy then becoming mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 35 to 43. deg. F. 18 to 24. deg. F. 35 to 41. deg. F.
Mid Slope Winds: Southwest around 15 mph with gusts to 30 mph. West around 15 mph in the evening becoming light. Gusts up to 35 mph. Light winds. Gusts up to 25 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy then becoming mostly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 28 to 34. deg. F. 14 to 19. deg. F. 28 to 34. deg. F.
Ridge Top Winds: Southwest 15 to 20 mph with gusts to 35 mph. Southwest 15 to 25 mph with gusts to 45 mph. Light winds becoming southwest around 15 mph with gusts to 30 mph in the afternoon.
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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