Eastern Sierra Avalanche Advisory - 3/3/17

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THIS AVALANCHE ADVISORY EXPIRED ON March 4, 2017 @ 6:50 am
Avalanche Advisory published on March 3, 2017 @ 6:50 am
Issued by Josh Feinberg - Eastern Sierra Avalanche Center
bottom line

Mostly stable avalanche conditions will exist through the backcountry today (Friday).  This doesn’t mean that avalanches will be impossible.  Warm temperatures could result in natural loose-wet point releases on steep sunny slopes that aren’t kept cool by today’s breezy conditions, and small isolated wind slabs sensitive to human triggering could exist in mid to upper elevations. 

How to read the advisory

Bottom Line

Mostly stable avalanche conditions will exist through the backcountry today (Friday).  This doesn’t mean that avalanches will be impossible.  Warm temperatures could result in natural loose-wet point releases on steep sunny slopes that aren’t kept cool by today’s breezy conditions, and small isolated wind slabs sensitive to human triggering could exist in mid to upper elevations. 

Avalanche Problem 1: Loose Wet
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As warm temperatures and sunny skies are expected again through the area today, loose wet avalanches may become possible on steep sunny slopes that aren’t kept cool by breezy SW winds.  These are most likely to originate near rock-bands which warm up from the sun.  One such slide was witnessed yesterday around noon in the June lake area.  Breezier conditions today will make this less likely as these winds will help keep wind-exposed slopes cool.  Increasing clouds in the afternoon will also help keep slopes cool.  Based on these predictions, steep southeasterly facing slopes will be of most concern mid to late morning.  While a resulting avalanche will likely remain small, it could still knock a rider off balance, partially bury someone in a terrain trap, or in a rare occasion entrain more snow and become larger and more threatening. 

Avalanche Problem 2: Wind Slab
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Strong SW winds reeked havoc on all but the most sheltered slopes during this past monday's small storm before calm conditions prevailed for the past 4 days giving windslabs a good period of time to stabilize.  Very isolated areas may still exist where a shallow old windslabs may still be sensitive to a human trigger.  Also with today’s increasing winds, new isolated windslabs may form near rare areas where soft transportable snow still exists.  Such a wind slab would be most concerning in steep complex terrain where even a small failure could knock someone off balance and result in a nasty fall. 

advisory discussion

We are coming to the end of one of our few small high pressure windows of the season so far.  Sunshine, calm winds and mild temperatures have persisted since Tuesday giving us all a needed break from storms and a reminder about why we all love California!  The latest storm on Monday dropped 1-7" of new snow (with greater amounts near Mammoth and June), and lots of wind out of the SW.  This left some great powder skiing in sheltered locations, and a wide variety of wind-affected snow and pockets of wind slab elsewhere.  The past few days have given these wind slabs a chance to heal for the most part, but small loose-wet point releases starting near rock-bands on solar aspects have begun as slopes have warmed. Today as winds begin to increase ahead of the next moderate storm coming in Saturday night, new small isolated wind slabs may form in the rare exposed areas that still have loose snow available for transport at mid to upper elevations.  Small loose-wet avalanches will be more of a limited concern on slopes with rock-bands being warmed by the sun, yet not cooled too much by the increasing winds, until clouds increase and slow this warming down even more.  

weather

Today (Friday) will begin sunny with mild temperatures and Increasing clouds and winds ahead of a moderate winter storm which will impact our area Saturday night into Sunday.  Expect high temperatures around 40 at 10,000’ and increasing winds out of the SW with gusts reaching 55mph this afternoon above 10,000’.   

For Saturday, expect partly cloudy skies, cooling temperatures with highs around 30 at 10,000’, and strong SW winds gusting up to 85mph above 10,000’.

For Saturday night thru Sunday Morning, a short intense band of snowfall is expected with 1-2ft of accumulation as a cold front pushes through the area, with snow levels below 6000’ and dropping.  Ridgetop winds will be over 100mph.  Lingering snow showers are expected thru the day Sunday before high pressure builds for next week.  

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Friday Friday Night Saturday
Weather: Sunny then becoming partly cloudy Mostly cloudy Partly cloudy
Temperatures: 40 to 48 deg. F. 23 to 28 deg. F. 35 to 45 deg. F.
Wind direction: SW SW SW
Wind speed: 5 to 15 mph with gusts to 25 mph 10 to 20 mph with gusts to 40 mph 15 to 30 mph. Gusts up to 50 mph increasing to 65 mph in the afternoon
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
  Friday Friday Night Saturday
Weather: Sunny then becoming partly cloudy Partly cloudy then becoming mostly cloudy Partly cloudy
Temperatures: 34 to 40 deg. F. 21 to 25 deg. F. 25 to 35 deg. F.
Wind direction: SW SW SW
Wind speed: 15 to 25 mph. Gusts up to 35 mph increasing to 55 mph in the afternoon 25 to 40 mph. Gusts up to 55 mph increasing to 75 mph after midnight 30 to 50 mph with gusts to 85 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.

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