Avalanche Advisory: Thursday - Dec 20, 2018 | Eastern Sierra Avalanche Center

Avalanche Problem 1: Wind Slab

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Strong SW winds today could find elusive patches of loose snow to blow around, some of which, if not blown into the atmosphere, could end up in small isolated pockets of fresh wind slab. Watch for small pockets of unstable snow on the leeward side of ridges, sidewalls of gullies, and around other features that promote drifting at mid and upper elevations on SE-E-N-NW facing slopes. Be wary of smooth hollow sounding snow. While a resulting avalanche is likely to be small, it could lead to a nasty fall in steep rocky terrain.

advisory discussion

In terms of stability, our underlying snowpack is holding strong. While some facets are forming near the surface, which could be a concern for future (fingers crossed) snow loads, at the moment there isn't too much to talk about besides the possibility of small isolated wind slabs on the surface. Winds over the past week have wreaked havoc on our snow surfaces. Firm and variable continue to be the words used to describe areas that are not sheltered from the wind. A fall on steeper exposed slopes could be hard to self-arrest, making crampons and ice axes recommended. While soft snow still exists in sheltered wooded areas, it is becoming thinner and thinner. Plenty of rocks, logs and stumps are poking thru or just barely buried waiting to snipe someone. Be careful out there and do your snow dances!

recent observations

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12/19 - June - Negatives: Stable wind slabs, snow conditions and weather.

12/19 - Mammoth - Off the back of Hemlock Ridge: sheltered snow conditions, moist snow.

12/19 - Mammoth - Sherwins: Moist surface snow.

Weather and CURRENT CONDITIONS

weather summary

Wind is again back to being the word of the day. Strong SW winds will increase thru today and remain strong thru tonight and into tomorrow as a result of a storm hitting the Pacific Northwest. Expect partly cloudy skies and mild temperatures reaching into the mid-40s around 10,000’. There is a slight chance of flurries after midnight, with no real accumulation expected.

Partly cloudy skies, cooler temperatures and strong SW winds are expected for Friday. A modest winter storm is on the radar for Sunday thru Monday, with some snow accumulation potential likely for Monday.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS

For 8,000 ft. to 10,000 ft.

	Thursday	Thursday Night	Friday
Weather:	Partly cloudy.	Partly cloudy. Slight chance of snow showers after midnight. Snow levels 7000 feet. Chance of precipitation is 10%.	Partly cloudy. Slight chance of snow showers in the morning. Snow levels 7000 feet. Chance of precipitation is 10%.
Temperatures:	44 to 49. deg. F.	25 to 30. deg. F.	36 to 42. deg. F.
Mid Slope Winds:	Southwest 15 to 20 mph with gusts to 45 mph.	Southwest 20 to 35 mph with gusts to 65 mph.	Southwest 15 to 30 mph. Gusts up to 60 mph decreasing to 35 mph in the afternoon.
Expected snowfall:	0 in.	trace in.	trace in.

Over 10,000 ft.

	Thursday	Thursday Night	Friday
Weather:	Partly cloudy then becoming sunny.	Partly cloudy then becoming mostly cloudy. Slight chance of snow showers after midnight. Snow levels 7000 feet. Chance of precipitation is 20%.	Partly cloudy. Slight chance of snow showers in the morning. Snow levels 7000 feet. Chance of precipitation is 10%.
Temperatures:	40 to 45. deg. F.	20 to 25. deg. F.	30 to 35. deg. F.
Ridge Top Winds:	Southwest 30 to 45 mph with gusts to 65 mph.	Southwest 35 to 50 mph increasing to 40 to 60 mph after midnight. Gusts up to 90 mph.	Southwest 40 to 60 mph with gusts to 100 mph decreasing to 20 to 30 mph with gusts to 45 mph in the afternoon.
Expected snowfall:	0 in.	trace in.	trace 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 Snowpack Summary is provided by the Eastern Sierra Avalanche Center, who is solely responsible for its content.