Avalanche Advisory: Monday - Mar 23, 2020 | Eastern Sierra Avalanche Center

THIS AVALANCHE ADVISORY EXPIRED ON March 24, 2020 @ 7:00 am
Avalanche Advisory published on March 23, 2020 @ 7:00 am

Issued by Josh Feinberg - Eastern Sierra Avalanche Center

Bottom Line

Winds are the primary architect of avalanches. Of course an architect can’t build without materials, which the last few day’s have provided plenty of in the form of up to 8” of loose dry snow sitting quietly just waiting to be manipulated, with another 1-3” possible today. MODERATE Avalanche danger will rise throughout today as increasing SW winds build dangerous windslabs on terrain at tree-line and above, possibly reaching CONSIDERABLE at upper elevations. Human triggering of avalanches will be possible, if not likely, and could be large enough to burry a person, with chances of an isolated natural avalanche as well. Loose dry point releases and sloughing remain a concern.

3. Considerable

Above Treeline

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

2. Moderate

Near Treeline

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

1. Low

Below Treeline

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

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

Avalanche Problem 1: Wind Slab

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Light snowfall over the past 4 days combined with the calmest winds we’ve seen all season have resulted in widespread areas of soft unconsolidated snow. As winds increase today out of the SW with gusts over 40mph over ridge tops, and another 1-3" of new snowfall possible today, fresh sensitive wind slabs will form quickly just below ridge lines, sidewalls of gullies, and around rock outcrops at tree line and above. Pay attention to clues such as blowing snow, cornice formation and shooting cracks to help you identify and avoid steep areas of denser deeper wind deposited snow where triggering an avalanche will be likely. An isolated natural avalanche at upper elevations could occur.

Avalanche Problem 2: Loose Dry

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Small point releases could occur from steep rocky terrain, especially as winds increase throughout today. Be aware of what is above you and manage your slough carefully In steep confined terrain at tree-line and above. NW-N-NE facing slopes are of most concern.

advisory discussion

After some discussion, we decided to drop The persistent slab problem yesterday despite a deeper underlying poor snowpack structure that can be found in many areas. The new snow from this past week has settled well, and without any reports of avalanches breaking down in deeper weak layers and the discontinuity that has been found across slopes, it is time to remove this as a problem. That doesn’t mean that a deeper slab avalanche is impossible, just very unlikely at this point. It is always important to do your own localized assessments and practice safe travel protocols by spreading out and exposing one person at a time to steeper slopes.

A shallow snowpack exists in many areas and sharks abound! Be aware of rocks and logs lurking just under the snow surface ready to snipe you. There have been some serious injuries already this past week. Tone it down, this is especially not a time to get hurt!

recent observations

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-3/23 - Bishop Area - Buttermilk Country: New snow, loose dry natural activity, no winds.

-3/23 - June - Mt. Wood: New snow, loose dry sloughing, no winds.

-3/23 - Mammoth Lakes Basin: Snow conditions and weather.

Weather and CURRENT CONDITIONS

weather summary

The last few days of surprisingly calm winds will change today as another weak low pressure system moves eastward across southern California bringing increased winds, snow showers and possible thunder. 1-3” of new snow is likely throughout today as SW winds increase with gusts into the 40mph range in the afternoon. High temperatures should reach 30°F around 10,000’.

SW winds will increase more dramatically overnight as a stronger cold front moves in from the Pacific Northwest, with ridge top gusts into the 80s after midnight. Snow showers continue through Thursday until sunshine and high pressure returns on Friday thru the weekend.

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:	Partly cloudy. Chance of thunderstorms and snow showers through the day. Snow levels below 7000 feet. Chance of precipitation is 35%.	Partly cloudy then becoming clear. Chance of thunderstorms and snow showers through the night. Snow levels below 7000 feet. Chance of precipitation is 25%.	Sunny. Chance of thunderstorms and snow showers through the day. Snow levels below 7000 feet. Chance of precipitation is 35%.
Temperatures:	30 to 40. deg. F.	20 to 25. deg. F.	28 to 38. deg. F.
Mid Slope Winds:	Light winds becoming southwest 15 to 25 mph in the afternoon. Gusts up to 40 mph.	Southwest 15 to 25 mph. Gusts up to 45 mph increasing to 65 mph after midnight.	Southwest 15 to 25 mph with gusts to 50 mph.
Expected snowfall:	80% probability up to 2 inches. 20% probability of 1 to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability up to 3 inches. 10% probability of 1 to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability of 1 to 3 inches. 10% probability of 1 to 2 inches. \| SWE = less than 0.10 inch. in.

Over 10,000 ft.

	Monday	Monday Night	Tuesday
Weather:	Mostly cloudy then becoming partly cloudy. Chance of thunderstorms and snow showers. Snow levels below 7000 feet. Chance of precipitation is 45%.	Partly cloudy. Chance of thunderstorms and snow showers through the night. Snow levels below 7000 feet. Chance of precipitation is 35%.	Partly cloudy. Chance of thunderstorms and snow showers. Snow levels below 7000 feet. Chance of precipitation is 40%.
Temperatures:	21 to 29. deg. F.	15 to 20. deg. F.	19 to 27. deg. F.
Ridge Top Winds:	West around 15 mph increasing to southwest 20 to 35 mph in the afternoon. Gusts up to 45 mph.	Southwest 25 to 35 mph with gusts to 50 mph increasing to 35 to 55 mph with gusts to 80 mph after midnight.	Southwest 25 to 35 mph. Gusts up to 60 mph decreasing to 45 mph in the afternoon.
Expected snowfall:	80% probability up to 2 inches. 20% probability of 1 to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability up to 3 inches. 10% probability of 1 to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability up to 3 inches. 10% probability of 1 to 2 inches. \| 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.