Avalanche Advisory: Saturday - Mar 23, 2019

THIS AVALANCHE ADVISORY EXPIRED ON March 24, 2019 @ 6:58 am
Avalanche Advisory published on March 23, 2019 @ 6:58 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Continued SW winds, the possibility of a few inches of new snow, and underlying firm sliding surfaces will keep avalanche danger MODERATE today at all elevations for fresh sensitive and older more stubborn wind slabs, especially around the Mammoth area. Human triggered avalanches will be possible.  Avalanche danger is less concerning for areas further south and north that have received less snow and wind this week. 

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
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    Large
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Wind slab avalanche conditions are remaining more sensitive than expected in some areas of the forecast zone.  Two different human triggered avalanches occurred yesterday in the Mammoth Lakes basin at high and low elevations.  Continued SW winds gusting into the 30s even at lower elevations, and the possibility of a few more inches of light snow today, will keep human triggering of fresh sensitive and older more stubborn avalanches very possible. Keep on the lookout for smooth deposits of slightly denser snow, signs such as shooting cracks, and clues such as cornice growth to help determine where these slabs may exist.  Do your own localized assessments before entering steeper exposed potentially wind-loaded terrain.  

advisory discussion

The Mammoth area has been a hotspot of avalanche activity all week since 6-10” of new snow fell Tuesday night and Wednesday, and 20-30mph SW to W winds continue to transport snow. Mammoth Mountain Ski Patrol reported widespread very sensitive storm slab and wind slab conditions on Wednesday and even into Thursday, and backcountry users triggered avalanches on Wednesday and Friday in the Lakes basin.  The widespread firm underlying melt-freeze crusts and old firm wind-board surfaces appear to be contributing factors in keeping avalanche conditions sensitive.  Multiple reports yesterday from areas south of Mammoth were of calm to light winds, but for Mammoth and potentially other areas, the winds continued to blow. Our zone is large, and variability is great.   

Weather and CURRENT CONDITIONS
weather summary

As a cold front pushes thru today expect mostly cloudy skies and chances of light snow (mostly before noon) with a few inches possible especially around Mammoth, and an inch or less for southern areas toward Bishop.  Temperatures should be cooler reaching the upper 20s around 10,000’ with breezy SW winds gusting into the 30s at lower elevations, and up to 40mph over ridge-tops.  

Tonight will be clear and cold with lows in the teens.  Tomorrow will be the clear day before unsettled weather returns for most of next week, with Tuesday night into Wednesday night looking to promise over a foot of snow for upper elevations. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy then becoming partly cloudy. Chance of snow in the morning, then chance of snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 55%. Clear. Sunny then becoming partly cloudy.
Temperatures: 29 to 39. deg. F. 12 to 18. deg. F. 34 to 44. deg. F.
Mid Slope Winds: Southwest 15 to 20 mph with gusts to 35 mph. West 15 to 20 mph. Gusts up to 30 mph in the evening. Light winds becoming south around 15 mph with gusts to 25 mph in the afternoon.
Expected snowfall: 70% probability of 1 to 4 inches. 30% probability of 4 to 6 inches. | SWE = up to 0.15 inch. in. 0 in. 0 in.
Over 10,000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy. Snow likely in the morning, then chance of snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 70%. Clear. Sunny then becoming partly cloudy.
Temperatures: 22 to 28. deg. F. 7 to 12. deg. F. 27 to 33. deg. F.
Ridge Top Winds: Southwest 15 to 30 mph with gusts to 40 mph. West 15 to 25 mph. Gusts up to 40 mph decreasing to 25 mph after midnight. Southwest 15 to 20 mph with gusts to 30 mph.
Expected snowfall: 70% probability of 1 to 4 inches. 30% probability of 4 to 6 inches. | SWE = up to 0.15 inch. 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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