Avalanche Advisory: Monday - Feb 11, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 12, 2019 @ 5:39 am
Avalanche Advisory published on February 11, 2019 @ 5:39 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Up to 3ft+ of snow fell over the weekend with strong winds.  Breezy west winds will continue today.  Avalanche danger is CONSIDERABLE at mid and upper elevations, and MODERATE at low elevations due to wind slabs and to a lesser extent storm slabs and loose-dry avalanches.  Human triggered avalanches remain likely. 

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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Up to 3ft+ of cold light snow fell at mid-elevations between Friday night and yesterday around noon, accompanied by strong to extreme winds from the Southwest, West, and Northwest. Lighter breezy west winds will continue today, still strong enough to transport snow in exposed areas at mid and upper elevations.  Smaller fresh wind slabs forming today will be easily triggered.  Larger slabs developed over the weekend will likely still be sensitive, but more stubborn to trigger.  Watch for areas of denser wind deposited snow, especially below ridgelines, sidewalls of gullies, and around other features that promote drifting.  Careful snowpack evaluation, cautious route-finding and conservative decision-making is essential.

Avalanche Problem 2: Storm Slab
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In areas protected form the wind, the low-density snow over the weekend has had some time to settle. While this will be more stable in some areas, in other areas it could be more likely to have a larger soft slab release rather than less consequential loose-dry releases.  Watch for subtle slope convexities for likely trigger points, and be aware of the increased danger of terrain traps such as gullies.  Evaluate the snow carefully before committing to steeper sheltered terrain.    

Avalanche Problem 3: Loose Dry
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The cold temperatures last night and today will keep the low-density snow over the weekend soft and unconsolidated in many sheltered areas.  Loose-dry sloughs in steep terrain could easily be large enough to sweep a skier or rider off their feet and result in a burial, especially in the confines of a chute or a slope ending in a terrain trap.  Ride one at a time, keep an eye on your partner, manage slough carefully, and recognize the potential for a larger storm-slab release.    

advisory discussion

Many more avalanche fatalities occur during the first beautiful day of blue skies and light winds after a big storm than during the actual HIGH danger rating days during the storm. Keep this in mind today, and choose your terrain wisely.  

Deep snow emersion continues to be a very real concern with another 3ft+ of new low-density snow over the weekend.  Falling into a tree-well head-first could be extremely difficult or impossible to get out of on your own.  Ski and ride with a partner, keep a close eye on one another, and give trees a wide berth. If you do end up stuck upside down in the snow, remember first to remain CALM and use deliberate motions to dig yourself out.   

recent observations
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2/10 - Mammoth Area - Sherwins -Multiple easy clean failures in storm snow in test pit, most noteable slightly more dense wind deposited snow at surface ontop of less dense.    

2/09 – Mammoth Area – Sherwins –wind slab development & deep snow

2/09 – Mammoth Area – Red Cone – wind slab and deep snow

2/09 – Bishop Creek –Bardini Canyon/Table Mtn – winds, snow conditions

2/09 - Bishop Creek –Table Mtn –wind slab development

2/09 - Mammoth Area -Sherwins-Sensitive wind slab conditions

Weather and CURRENT CONDITIONS
weather summary

Our one full day of sunshine this week is today.  Below zero temperatures last night will rise into the low 20s around 10,000’, with breezy west winds.  Snowfall starts again Tuesday night, with another major warmer and wetter storm projected for Wednesday and Wednesday night.  More chances of snow and colder temps return thru the end of the week. 

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: Sunny. Clear. Sunny then becoming partly cloudy. Slight chance of snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 10%.
Temperatures: 23 to 29. deg. F. 4 to 10. deg. F. 24 to 32. deg. F.
Mid Slope Winds: West around 15 mph with gusts to 40 mph. Southwest 15 to 20 mph. Gusts up to 35 mph increasing to 45 mph after midnight. Southwest 15 to 25 mph. Gusts up to 45 mph increasing to 60 mph in the afternoon.
Expected snowfall: none in. none in. No accumulation. | SWE = trace amounts. in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy then becoming sunny. Clear. Sunny then becoming partly cloudy. Slight chance of snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 15%.
Temperatures: 15 to 20. deg. F. 1 below to 5 above zero. deg. F. 17 to 22. deg. F.
Ridge Top Winds: West 25 to 35 mph with gusts to 55 mph decreasing to 15 to 30 mph with gusts to 40 mph in the afternoon. Southwest 15 to 30 mph with gusts to 45 mph increasing to 25 to 35 mph with gusts to 60 mph after midnight. Southwest 25 to 40 mph increasing to 30 to 50 mph in the afternoon. Gusts up to 80 mph.
Expected snowfall: none in. none in. No accumulation. | SWE = trace amounts. 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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