Avalanche Advisory: Thursday - Jan 2, 2020

THIS AVALANCHE ADVISORY EXPIRED ON January 3, 2020 @ 6:54 am
Avalanche Advisory published on January 2, 2020 @ 6:54 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

MODERATE avalanche danger exists today at all elevations due to new wind slabs formed by yesterday and last night’s very strong NW winds.  Human triggering of sensitive wind slabs will be possible on the leeward side of certain exposed terrain features.   

 

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    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
  • Size ?
    Historic
    Very Large
    Large
    Small

More snow transport than expected occurred with yesterday’s very strong winds, with some sensitive small wind slabs being triggered at mid-elevation on the leeward side of an exposed ridge.  Winds increased even more last night gusting into the 90 mph range over high ridge tops, and are expected to continue today gusting up to 60mph before decreasing this afternoon.  While these winds are predominantly out of the NW, wind directions have been variable at lower elevations.  Beware of new dense snow deposits on the leeward side of ridges, sidewalls of gullies and across slope depressions.  Watch for clues such as blowing snow, cornice formation and shooting cracks, and do your own localized assessments before committing to steep consequential terrain. Larger fresh slabs may actually be found at mid-elevations due to the limited amount of loose snow available for transport up high.  

 
advisory discussion

While wind slabs are by far the greatest concern today, with fully sunny skies, slightly warmer air temperatures, and slightly less wind, small loose wet point releases will be possible today on sunny aspects as they warm.  Last night’s clear skies allowed for a fairly solid refreeze of slopes, so this concern should remain small.  

 
recent observations
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1/1 - June - Negatives:  Lots of wind transport, sensitive wind slabs at mid-elevations.

1/1 - Mammoth Lakes Basin to Pika Peak: Wind transport.

1/1 - Mammoth Lakes Basin - TJ Bowl: Winds, small rollerballs.

1/1 - Mammoth Area - Solitude ridge: Warm snow, small rollerballs.

Weather and CURRENT CONDITIONS
weather summary

Sunny skies and mild temperatures with highs in the mid to upper 30s around 10,000’ are on tap for today.  The strong winds yesterday and last night will continue today, but more in the moderate range blowing out of the NW over ridgetops and from the south at some mid-elevations.

 

More sun, mild temperatures and less wind are expected for Friday before winds and clouds increase again on Saturday.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Thursday Thursday Night Friday
Weather: Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%. Clear then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 37 to 42. deg. F. 20 to 25. deg. F. 40 to 46. deg. F.
Mid Slope Winds: Northwest around 15 mph. Gusts up to 40 mph decreasing to 30 mph in the afternoon. Light winds. Light winds becoming southwest around 15 mph with gusts to 30 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Thursday Thursday Night Friday
Weather: Sunny. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 0%. Clear then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 0%. Partly cloudy then becoming mostly cloudy. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 32 to 37. deg. F. 21 to 26. deg. F. 35 to 41. deg. F.
Ridge Top Winds: Northwest 25 to 35 mph with gusts to 60 mph decreasing to 15 to 30 mph in the afternoon. Northeast 15 to 20 mph with gusts to 35 mph. Light winds becoming southwest 15 to 25 mph with gusts to 35 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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