Avalanche Advisory: Saturday - Dec 22, 2018

THIS AVALANCHE ADVISORY EXPIRED ON December 23, 2018 @ 6:15 am
Avalanche Advisory published on December 22, 2018 @ 6:15 am

Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

Bottom Line

How to read the advisory

Human triggered avalanches will be possible today in isolated areas or extreme terrain on SE-E-N-NW facing slopes in upper to middle elevations. Avalanches today may be small in size, but they can still pose a hazard when traveling in exposed terrain. Evaluate snow and terrain carefully, especially convex rolls and unsupported slopes. Early season obstacles exist!

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Above Treeline

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Near Treeline

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Below Treeline

Avalanche Problem 1: Wind Slab

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The extreme southerly winds of yesterday began to mellow around 530pm and by 900pm they became light to calm up high. Although not much snow transport was observed along the Mammoth crest yesterday there were reports of significant visible snow transport along the 395 corridor between Mammoth and Bishop on the higher peaks. Yesterday’s brief snowfall loaded specific areas N-NE from 4-6” deep, but there was no reported or observed avalanche activity in the Mammoth area. New snow was wet and well bonded to old snow surfaces, but travelers should still be on the lookout for loaded wind features and pillows today. It’s possible with last night’s clear conditions and cooler temperatures that loaded snow could stiffen up a bit and build enough tension to be affected by skier pressure.

advisory discussion

The new snow yesterday coupled with strong to extreme winds loaded lee slopes primarily on the N-NE in the mid to upper terrain where topography is conducive to capturing or slowing down blowing snow. Seek out low-consequence test slopes to see if new loaded snow is sensitive and pay attention to red flags such as drummy sounding snow or shooting cracks. Always be observant for specific terrain features such as terrain traps, convex loaded slopes or slopes over exposed rock, cliff or trees. Although we have a pasting of fresh new snow on the shady aspects, the biggest danger out there right now is thin and variable conditions everywhere. Areas around the Mammoth crest and specific sheltered NE high alpine couloir features hold the deepest snow from 120-160cm while lower terrain such as the Sherwins have around 60-70cm of snow at their maximum. Snow depths drastically decrease as you descend and 15-30cm snow depth is standard in the low lying areas.

recent observations

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12/21 - Mammoth Area - Mammoth Crest snow conditions

12/20 - Virginia Lakes Area - snow conditions

12/19 - June Lake Area - Negatives snow conditions

Weather and CURRENT CONDITIONS

weather summary

A beautiful day is on tap for Saturday with sunny to partly cloudy conditions. Temperatures will be above freezing at both the mid and upper elevations and winds are forecasted to be light to moderate out of the West. A calmer day wind wise will be a nice rest from the blustery conditions we have been experiencing most of last week. Freezing temperatures from the teens to mid-20’s are expected tonight with continued calm weather into Sunday. A moderate winter storm is expected to move through the area Christmas Eve and with it perhaps up to a foot of snow for the mountains, hopefully more!

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:	Sunny then becoming partly cloudy	Mostly cloudy	Partly cloudy
Temperatures:	39 to 44. deg. F.	20 to 25. deg. F.	38 to 44. deg. F.
Mid Slope Winds:	Light winds.	Southwest 10 to 15 mph with gusts to 35 mph.	West 10 to 15 mph in the morning becoming light. Gusts up to 30 mph.
Expected snowfall:	0 in.	0 in.	0 in.

Over 10,000 ft.

	Saturday	Saturday Night	Sunday
Weather:	Partly cloudy	Mostly cloudy	Partly cloudy
Temperatures:	34 to 39. deg. F.	16 to 21. deg. F.	32 to 37. deg. F.
Ridge Top Winds:	West 10 to 15 mph. Gusts up to 25 mph in the afternoon.	Southwest 15 to 25 mph with gusts to 40 mph.	West 15 to 20 mph with gusts to 35 mph.
Expected snowfall:	0 in.	0 in.	0 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.