Avalanche Advisory: Saturday - Feb 29, 2020

THIS AVALANCHE ADVISORY EXPIRED ON March 1, 2020 @ 6:33 am
Avalanche Advisory published on February 29, 2020 @ 6:33 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

LOW avalanche danger exists at all Elevations. If new snow accumulations start earlier than expected Saturday, be on the lookout for isolated pockets of Wind Slab on terrain features conducive to capturing transported snow. Avalanche danger may ramp up to CONSIDERABLE for the early morning hours of Sunday if we see the high end of forecasted snow totals (12”) combined with extreme SW winds.

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
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Strong SW winds and cloudy conditions should keep loose wet concerns in check for solar aspects, but surface warming and unsupportable snow should be evaluated with last night’s weak re-freeze and continuing warm temperatures for lower elevations today. Overall conditions are predicted to dramatically change overnight with a quick, but heavy shot of new snow along the Sierra crest in the early morning hours of Sunday. 5-12” of potential new snow combined with strong to extreme SW winds may dramatically bump up the Avalanche Hazard to the CONSIDERABLE range by daybreak Sunday. While everybody is eager for fresh snow and some softer conditions, we should be cognizant of the incredibly firm, slick and shallow residing old snow surfaces that the new snow will be falling on.

If new snow begins to accumulate during the day Saturday, hazardous pockets of wind slab may develop on N-NE aspects on terrain features that collect snow such as gullies, couloirs, and areas adjacent to ridgeline and rockbands. Riders should be observant and adjust travel plans in case snow accumulations and deposition ramp up with expected strong SW winds. Be prepared for developing pockets or ribbons of cold new snow that will easily want to move down slope on hard, wind shorn slick surfaces. New snow accumulations will be sitting on boiler plate, firm conditions if you’re attempting north facing couloirs or high exposed alpine slopes. 

Weather and CURRENT CONDITIONS
weather summary

An abrupt change to our seemingly perpetual sunny skies will begin Saturday with cloudy skies and blustery SW winds in the mountains. Temperatures will remain warm, reaching the high 40sF at lower mountain elevations and hovering around freezing above 10000ft. SW Winds will ramp up throughout the day from the 30mph range up to 55mph with gusts as high as 85mph on ridgetop. Upwards of  5-12” of snow is forecast for the Sierra crest possibly starting as early this evening, but more than likely the brunt of the storm hitting in the early morning hours of Sunday.

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. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 0%. Partly cloudy then becoming mostly cloudy. Chance of snow showers through the night. Snow levels below 7000 feet. Chance of precipitation is 50%. Mostly cloudy. Snow showers likely in the morning, then snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 85%.
Temperatures: 37 to 47. deg. F. 14 to 20. deg. F. 18 to 26. deg. F.
Mid Slope Winds: Southwest 20 to 35 mph with gusts to 55 mph. Southwest 25 to 40 mph decreasing to 20 to 30 mph after midnight. Gusts up to 60 mph. Northwest 15 to 25 mph with gusts to 45 mph.
Expected snowfall: 0 in. 70% probability of 1 to 4 inches. 30% probability of 4 to 6 inches. | SWE = up to 0.25 inch. in. 80% probability of 1 to 4 inches. 20% probability of 3 to 6 inches. | SWE = 0.15-0.25 inch. in.
Over 10,000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 5%. Partly cloudy then becoming mostly cloudy. Chance of snow showers through the night. Snow levels below 7000 feet. Chance of precipitation is 55%. Mostly cloudy. Snow showers likely in the morning, then snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 85%.
Temperatures: 27 to 35. deg. F. 7 to 13. deg. F. 12 to 18. deg. F.
Ridge Top Winds: Southwest 30 to 45 mph increasing to 35 to 55 mph in the afternoon. Gusts up to 85 mph. Southwest 40 to 55 mph decreasing to 30 to 45 mph after midnight. Gusts up to 80 mph. Northwest 15 to 30 mph with gusts to 45 mph.
Expected snowfall: 0 in. 70% probability of 1 to 4 inches. 30% probability of 4 to 7 inches. | SWE = up to 0.30 inch. in. 80% probability of 2 to 5 inches. 20% probability of 4 to 7 inches. | SWE = up to 0.30 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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