Avalanche Advisory: Monday - Jan 25, 2021

THIS AVALANCHE ADVISORY EXPIRED ON January 26, 2021 @ 6:44 am
Avalanche Advisory published on January 25, 2021 @ 6:44 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Up to 5” of low-density snow fell quickly last night, and another 1-3” are expected thru today accompanied by ideal windspeeds for wind slab formation.  Human triggered wind slab avalanches will be possible in areas where deeper denser wind-drifted snow deposits exist. Avalanche danger is MODERATE near and above treeline, and LOW in sheltered trees. Evaluate snow and terrain carefully and identify features of concern.  

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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    Certain
    Very Likely
    Likely
    Possible
    Unlikely
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    Historic
    Very Large
    Large
    Small

2-4” of light snow fell Saturday, up to 5” more fell last night especially around Mammoth, and another 1-3” are possible today. Winds finally settled into a consistent SW flow yesterday, and should continue thru today at light to moderate (20-30mph) speeds, which should easily transport this low-density snow.  Watch for fresh deposits of denser wind drifted snow especially on the leeward side of ridgelines and sidewalls of gullies on NW-NE-SE facing slopes.  While relatively small, these drifts will likely be sensitive today, and triggering one could lead to a nasty ride through obstacle-ridden terrain.  

advisory discussion

Firm underlying surfaces are widespread underneath this new light low density snow.  Ski or boot crampons could be quite helpful in moderately steep terrain even at lower elevations.     

Weather and CURRENT CONDITIONS
weather summary

As the first in a series of low-pressure systems for this week winds down, 1-3” of additional snowfall thru today is possible especially around Mammoth.  Expect a cloudy chilly day with highs reaching the mid-teens around 10,000’ and light to moderate W to SW winds in the 20-30mph range at mid to upper elevations.  

Tuesday should be a sunny calm day before a real season-changing storm is continuing to look more and more likely starting late Tuesday night with snowfall finally expected to be measured in feet!  A Winter Storm Warning is in effect for Tuesday night thru early Friday morning.    

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: Cloudy. Snow likely in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 75%. Cloudy. Chance of snow in the evening. Snow levels below 7000 feet. Chance of precipitation is 45%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 16 to 22. deg. F. 1 to 7. deg. F. 17 to 25. deg. F.
Mid Slope Winds: West 15 to 20 mph with gusts to 40 mph. Northwest around 15 mph with gusts to 35 mph. Light winds becoming southwest around 15 mph in the afternoon.
Expected snowfall: 80% probability of 1 to 3 inches. 20% probability no accumulation. | SWE = up to 0.15 inch. in. 40% probability up to 1 inch. 60% probability no accumulation. | SWE = less than 0.10 inch. in. 0 in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Cloudy. Snow likely in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 80%. Mostly cloudy. Chance of snow in the evening. Snow levels below 7000 feet. Chance of precipitation is 45%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 5%.
Temperatures: 8 to 15. deg. F. 4 below to 2 above zero. deg. F. 9 to 17. deg. F.
Ridge Top Winds: West 15 to 20 mph with gusts to 40 mph. West around 15 mph with gusts to 30 mph. West around 15 mph with gusts to 25 mph.
Expected snowfall: 80% probability 1 to 3 inches. 20% probability no accumulation. | SWE = up to 0.20 inch. in. 40% probability up to 1 inch. 60% probability no accumulation. | SWE = less than 0.10 inch. 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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