Avalanche Advisory: Monday - Feb 18, 2019

THIS AVALANCHE ADVISORY EXPIRED ON February 19, 2019 @ 6:28 am
Avalanche Advisory published on February 18, 2019 @ 6:28 am
Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

The avalanche danger is MODERATE at Upper to Mid elevations today. LOW avalanche danger resides at lower elevations. WIND SLAB and CORNICES are the biggest hazards present today. Although overall snowpack conditions are stabilizing, identifying features of concern, and carefully moving into more committing terrain will need focused evaluation.

2. Moderate

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

2. Moderate

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

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
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Winds shifted to a Northerly orientation last night and will be prevailing at moderate speeds today. There is plenty of transportable snow on the northern aspects to be redistributed and form fresh wind slab on SOUTHERLY and WESTERLY aspects. In fact, be aware that wind slab could be residing on ALL ASPECTS at higher and middle elevations as previous storm winds were consistently blowing from the south and west. It is forecast to be mostly cloudy today and cold, but also pay attention, if the sun does comes out, that solar gain could help loosen fresh deposits on solar aspects. Take note that a RAIN CRUST was created up to around 10000ft during Feb 14/15. Not only does this shiny, firm crust present a fall hazard to riders, but makes a good sliding surface for freshly deposited wind slab on aspects that were previously wind scoured down to this crust (again…think south and west aspects). Although new snow has been shown to be bonding fairly well to this rain layer where it was buried, pay attention to where it may now just be getting covered up by new cold wind deposits with less bonding potential.

Avalanche Problem 2: Cornice
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The high alpine country has been in the clouds for seemingly weeks, and for the most part observations of the higher ridgelines have been few and far between. With a clear afternoon yesterday, it was apparent there has been significant CORNICE growth primarily on EASTERLY and NORTHERLY aspects throughout the range. Give these curling wavelike features a wide berth and make sure you are well on terra firma on the windward side of ridges where cornices reside. Cornice fall not only is hazardous if it gives way beneath you, but can affect travelers if it falls from above when you are travelling on slopes below. Cornice fall can be the big trigger that starts avalanches on slopes below as the falling blocks can be of tremendous weight and scale. Cold temps and forecasted cloudy skies should keep these relatively locked up today, but if sunnier conditions prevail, be aware that solar gain could contribute to loosening freshly formed cornices on easterly aspects.

advisory discussion

THANKS TO ALL OUR VOLUNTEER OBSERVERS.  It has been a great help to have all the additional snowpack information during our massive storm cycle of February.  Keep up the good work as this is a great community effort.  Enjoy and be safe out there!!!

recent observations
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2/17 – Mammoth Area – Punta Bardini – Snow Conditions/Buried rain layer

2/17 – Rock Creek Area - Red Mountain – Cornices & rain crusts

2/17 – Mammoth Area – Sherwins –Evidence of Large Avalanche from previous storm cycle

2/16 – Bishop Creek –Table Mtn - rain crust, snow conditions

2/16 – Mammoth Area – Red cone - sensitive surface conditions

2/15 – Lee Vining Area - Lundy Canyon – Rain effects and new snow

Weather and CURRENT CONDITIONS
weather summary

Very cold conditions with mostly cloudy skies are on tap for today. Be prepared for temps in the low teens (11-19F) below 10000ft and single digit temperatures (3-8F) above 10000ft. Scattered snow showers are also expected with moderate to strong northerly winds. Up to 1” of snow is forecast for the mountains today. It is supposed to clear up tonight and with it temperatures could drop into the negative range where inversions occur. A slider system with light cold snow is still looking good for our area beginning Wednesday.

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: Mostly cloudy. Scattered snow showers. Snow levels below 7000 feet. Chance of precipitation is 25%. Partly cloudy then becoming clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 11 to 19. deg. F. 2 below to 4 above zero. deg. F. 21 to 27. deg. F.
Mid Slope Winds: North around 15 mph with gusts to 35 mph. North around 15 mph with gusts to 35 mph. North around 15 mph. Gusts up to 35 mph.
Expected snowfall: Up to 1 inch. | SWE = trace amounts. in. No accumulation. | SWE = none. in. No accumulation. | SWE = none. in.
Over 10,000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Isolated snow showers. Snow levels below 7000 feet. Chance of precipitation is 20%. Partly cloudy then becoming clear. Snow levels below 7000 feet. Chance of precipitation is 0%. Sunny. Snow levels below 7000 feet. Chance of precipitation is 0%.
Temperatures: 3 to 8. deg. F. 5 below to zero. deg. F. 14 to 19. deg. F.
Ridge Top Winds: North 15 to 30 mph with gusts to 45 mph. North 15 to 30 mph with gusts to 50 mph. North 20 to 30 mph with gusts to 50 mph.
Expected snowfall: Up to 1 inch. | SWE = trace amounts. in. No accumulation. | SWE = none. in. No accumulation. | SWE = none. 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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