Avalanche Advisory: Monday - Dec 2, 2019

THIS AVALANCHE ADVISORY EXPIRED ON December 3, 2019 @ 6:31 am
Avalanche Advisory published on December 2, 2019 @ 6:31 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

Wind slab and new snow instabilities on Northerly and Easterly aspects near and above tree line will be of greatest concern Monday. The Mammoth area saw an additional 20” plus of snow Sunday combined with SW winds. The Thanksgiving storm cycle has seen totals reaching 6ft of snowfall with 5” of water. Although the snowpack has already begun to settle and adjust deep snow immersion and buried early season obstacles also remain primary hazards. Evaluate snow and terrain carefully and identify features of concern.

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Below Treeline
advisory discussion

Snow sports enthusiasts will be very thankful for the Thanksgiving storm cycle which has transformed the Sierra very rapidly from a late autumn desiccated landscape back into winter with a substantial blanket of snow. It’s great to be back writing about snow after a 4 month hiatus where we skied deep into July on last season’s hefty snowpack.  

Cold temperatures brought snow levels down to 2000ft and deposited upwards of 4’ of settled snow in the Mammoth Area at the 9000ft elevation. Observations have been limited in the alpine with the most avalanche activity being recorded at the ski area on Friday 11/29 where there were some significant natural and explosive triggered wind slab avalanches on northerly aspects around the 9-10000ft elevation. Wind slabs ranged from 12” to 4ft in depth.  With continued strong SW winds and substantial amount of new snowfall on all aspects, be particularly aware of areas conducive to capturing wind transported snow. Northerly aspects will be of main concern with SW winds slated to continue for the forecast area.  With the season starting off with a bang, it’s a good time to hone and re-visit the skills of companion rescue and proper travel protocols in avalanche terrain. Be sure to double check that all your equipment is in proper working order and to refine and perk up those avalanche hunter observations. Be on the lookout for red flags such as recent avalanche activity, shooting cracks, whoompfing of the snowpack, and fat pillowed snow features.

If you’re getting out and about, please post any pertinent avalanche or snow condition observations to the ESAC observation page.

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12/1: Mammoth Rock – Sherwins- Snow conditions

12/1: Mammoth Area – Earthquake Dome – Snow conditions

12/1: Convict Area – Mono Jim Pk – Conditions

Weather and CURRENT CONDITIONS
weather summary

Snow showers in the Sierra today (2-6”) with continued SW winds and temperatures hovering in the high 20sF to low 30sF. After a break in activity Tuesday the next storm targets the Eastern Sierra and Mono County on Wednesday. Stormy conditions are predicted to continue with another system moving in for next weekend with additional snow accumulation.

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 in the morning, then snow and rain likely in the afternoon. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 80%. Mostly cloudy. Chance of snow. Snow levels 7500 feet. Chance of precipitation is 50%. Mostly cloudy. Slight chance of snow through the day. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 15%.
Temperatures: 31 to 36. deg. F. 22 to 27. deg. F. 30 to 35. deg. F.
Mid Slope Winds: South around 15 mph. Gusts up to 45 mph decreasing to 30 mph in the afternoon. Light winds. Gusts up to 25 mph in the evening. Light winds.
Expected snowfall: 80% probability of 2 to 5 inches. 20% probability up to 2 inches. | SWE = 0.25-0.50 inch. in. 80% probability of 1 to 3 inches. 20% probability of 2 to 3 inches. | SWE = up to 0.20 inch. in. No accumulation. | SWE = less than 0.10 inch. in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels 7000 feet increasing to 8000 feet in the afternoon. Chance of precipitation is 90%. Mostly cloudy. Snow likely. Snow levels 8000 feet. Chance of precipitation is 55%. Mostly cloudy. Slight chance of snow through the day. Snow levels 7000 feet increasing to 8000 feet in the afternoon. Chance of precipitation is 20%.
Temperatures: 26 to 31. deg. F. 19 to 24. deg. F. 25 to 31. deg. F.
Ridge Top Winds: Southwest 20 to 35 mph. Gusts up to 60 mph in the morning. South 15 to 25 mph. Southwest around 15 mph. Gusts up to 25 mph in the morning.
Expected snowfall: 80% probability of 3 to 6 inches. 20% probability up to 3 inches. | SWE = 0.25-0.50 inch. in. 80% probability of 1 to 3 inches. 20% probability of 2 to 3 inches. | SWE = 0.15-0.25 inch. in. No accumulation. | SWE = less than 0.10 inch. 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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