Avalanche Advisory: Saturday - Dec 7, 2019

THIS AVALANCHE ADVISORY EXPIRED ON December 9, 2019 @ 6:55 am
Avalanche Advisory published on December 7, 2019 @ 6:55 am
Issued by Steve Mace - ESAC

Fresh, sensitive wind slabs will be the primary concern this weekend on northerly and easterly aspects at mid and upper elevations. Storm slab avalanches will also be a concern in shelterd areas on all aspects as new snow accumulates throughout the forecast area. With heavy snowfall and very strong winds impacting the area this weekend, we can expect the avalanche hazard to rise quickly throughout the day on Saturday and into Sunday. 

 

*Danger ratings can not be assigned accurately for multi-day advisories as conditions can change drastically from one day to the next. Daily Advisories with danger ratings will begin on December 20th.*

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advisory discussion

Be on the lookout for changing conditions this weekend as a major winter storm impacts the area. 1-3’ of heavy wet snow is expected throughout the weekend accompanied by gale-force winds. 

Expect fresh wind slabs to be most prevalent on northerly and easterly aspects.  It is important to remember that strong winds can distribute snow in unexpected ways. Be on the look out for wind deposits at lower elevations, further down slopes, and in more shelterd areas than you may typically expect to find them. Do your own localized assessments and be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions.   Surface clues such as blowing snow, recent cornice growth, and uneven snow surfaces can help you identify and avoid areas of recent wind deposit.

Expect the risk of storm slab avalanches to increase on all aspects as the snow starts to accumulate throughout the day on Saturday.  Storm Slabs will be most concerning at lower elevations and in terrain that is shelterd from the wind. Watch for signs of instability such as shooting cracks, wumphing, and recent avalanche activity, and be aware that loose unconsolidated sloughs can entrain quite a bit of snow and potentially carry a skier through some unpleasant terrain.  Heightened awareness is recommended in sheltered areas over 35°.

It is also important to remember that a thin preseason snowpack still exists throughout the forecast area.  While this weekend's snow will help to cover the remaining obstacles, thinly covered rocks and trees are still a real concern. Practice safe travel techniques and use conservative route choice if heading into the backcountry this weekend. 

 

Weather and CURRENT CONDITIONS
weather summary

*A Winter Storm Warning is in effect until noon on Sunday* 

 

Heavy snowfall and strong winds will continue throughout the day on Saturday as a winter storm makes its way through the area.  Total Snow accumulations of 1-3 feet are expected by midday on Sunday above 7000’ throughout the forecast area with the bulk of the precipitation expected at upper elevations. Strong southerly winds will accompany this snowfall with gusts as high as 90mph at upper elevations and 50mph at lower elevations.  

 The storm will intensify throughout the day on Saturday, with the most intense snowfall expected on Saturday night.  Very strong winds will continue throughout the evening with a chance of Thunderstorms on Saturday night. 

We can expect Snow showers to ease by midday on Sunday as this storm pushes through the area. Winds are expected to decrease throughout the day Sunday with moderate SW winds and ridgetop gusts in the 45-65 mph range expected at 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: Cloudy. Snow. Snow levels 7500 feet. Chance of precipitation is 90%. Cloudy. Snow and chance of thunderstorms. Snow levels below 7000 feet. Chance of precipitation is 95%. Mostly cloudy. Snow likely. Snow levels below 7000 feet. Chance of precipitation is 70%.
Temperatures: 31 to 37. deg. F. 21 to 26. deg. F. 24 to 30. deg. F.
Mid Slope Winds: South 20 to 35 mph with gusts to 60 mph. South 15 to 30 mph. Gusts up to 70 mph decreasing to 50 mph after midnight. Southwest around 15 mph. Gusts up to 45 mph decreasing to 35 mph in the afternoon.
Expected snowfall: 70% probability of 4 to 10 inches. 30% probability of 3 to 7 inches. | SWE = 0.40-0.65 inch. in. 70% probability of 7 to 13 inches. 30% probability of 12 to 16 inches. | SWE = 0.55-1.05 inches. in. 70% probability up to 3 inches. 30% probability of 3 to 6 inches. | SWE = up to 0.15 inch. in.
Over 10,000 ft.
Saturday Saturday Night Sunday
Weather: Cloudy. Snow. Snow levels 7500 feet. Chance of precipitation is 95%. Cloudy. Snow and chance of thunderstorms. Snow levels 7000 feet. Chance of precipitation is 95%. Mostly cloudy. Snow in the morning, then snow likely in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 80%.
Temperatures: 24 to 30. deg. F. 17 to 22. deg. F. 18 to 23. deg. F.
Ridge Top Winds: Southwest 35 to 45 mph with gusts to 85 mph. Southwest 35 to 55 mph with gusts to 90 mph decreasing to 30 to 45 mph with gusts to 65 mph after midnight. Southwest 25 to 40 mph with gusts to 65 mph decreasing to 20 to 30 mph with gusts to 45 mph in the afternoon.
Expected snowfall: 70% probability of 5 to 11 inches. 30% probability of 4 to 9 inches. | SWE = 0.50-0.75 inch. in. 70% probability of 9 to 15 inches. 30% probability of 12 to 16 inches. | SWE = 0.75-1.25 inches. in. 70% probability of 1 to 3 inches. 30% probability of 3 to 6 inches. | SWE = up to 0.15 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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