Avalanche Advisory: Tuesday - Mar 26, 2019 | Page 2

THIS AVALANCHE ADVISORY EXPIRED ON March 27, 2019 @ 6:50 am
Avalanche Advisory published on March 26, 2019 @ 6:50 am

Issued by Chris Engelhardt - Eastern Sierra Avalanche Center

Bottom Line

The avalanche danger will be MODERATE at Upper and Middle elevations. WIND SLAB avalanches will be possible to trigger primarily on N-E aspects and could develop on ALL ASPECTS due to extreme alpine winds and the possible addition of new snowfall (1-2” today). Evaluate snow and terrain carefully both on the way up and down today!

2. Moderate

Above Treeline

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

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.

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

Avalanche Problem 1: Wind Slab

Type ?
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Certain

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Historic

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Large

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Be on the lookout for fresh and sensitive wind slab primarily on NORTHERLY-EASTERLY slopes. SOUTHERLY winds at optimal speeds have been actively loading transportable snow to leeward slopes with extreme gusts redistributing snow in dynamic and unpredictable ways both at high and mid elevations. There has been multiple reported skier triggered avalanches over the previous 3 days where skiers/riders have triggered wind slabs in steep confined terrain and while ascending convex wind loaded slopes. These human triggered slides have been large enough to carry a person down slope and partially bury them in some cases (D2 scale). These reported slides have been reported on not only northerly aspects, but also on SE aspects. CORNICE FAILURE has also been reported as a possible trigger in some observed avalanches. Pay attention for actively transporting snow, firm harder slab residing above softer weaker snow, freshly formed cornices, and red flags such as shooting cracks, and drummy, hollow sounding snow.

Avalanche Problem 2: Cornice

Type ?
Aspect/Elevation ?
Likelihood ?

Certain

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Likely

Possible

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Historic

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Avoid CORNICES particularly on EASTERLY aspects. Cornice fall not only is hazardous if it gives way beneath you, but can affect travelers on slopes below. Pay specific attention to overhead hazards if your ski objective requires you to ascend slopes or coloirs below hanging cornices. Think twice before spending time exposed to freshly formed overhead cornices. Cornice fall can be the big trigger that starts avalanches on slopes below as the falling blocks can be of tremendous weight and scale. Give these curling wavelike features a wide berth and make sure you are well on terra firma if travelling on top of ridges where cornices reside.

recent observations

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3/24 – Bridgeport Area – Kettle Peak –Skier triggered avalanche

3/25 – Mammoth Area – Mammoth Crest “Jaws” – cornice collapse

3/25 - Lundy Canyon - Deer Creek - Strong to Extreme winds

3/24 – Big Pine Area/Birch Lake–“The Thumb” – (reported 3/25) Skier triggered avalanche

3/24 – Bridgeport Area – Matterhorn – Skier triggered avalanches

3/24 – Bishop Area/Buttermilk Country - Basin Mtn – Skier triggered small avalanche on SE aspect

3/23 – Lee Vining – Ripper Chute – (reported 3/24) Skier triggered avalanche/partial burial

Weather and CURRENT CONDITIONS

weather summary

SW winds will continue to rake the Sierra with gusts up to 70mph with consistent strong to extreme velocities for the mid to higher elevations. It will be mostly cloudy with rain and snow possible at the 8-10000elev band and chance of snow showers (up to 2”) above 10000ft elev. Above freezing temperatures are forecast for mid to lower elevation bands at 32-42F. 27-33F will be keep things relatively cooler above 10000ft. A WINTER STORM WARNING goes into effect tonight at 11pm through 11pm Wednesday. Peak precipitation rates are supposed to occur during the daylight hours Wednesday where we could see snowfall rates of 1-2” per hour. Above 7000ft the Sierra is expecting 1-2’ of snow with upwards of 3’ in localized areas!

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

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

	Tuesday	Tuesday Night	Wednesday
Weather:	Mostly cloudy. Chance of snow and rain. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 20%.	Mostly cloudy. Chance of snow and rain. Snow levels 7500 feet decreasing to below 7000 feet after midnight. Chance of precipitation is 25%.	Cloudy. Snow in the morning, then snow showers in the afternoon. Snow levels 7000 feet. Chance of precipitation is 100%.
Temperatures:	32 to 42. deg. F.	24 to 29. deg. F.	30 to 39. deg. F.
Mid Slope Winds:	Southwest 15 to 30 mph with gusts to 65 mph.	Southwest 20 to 30 mph with gusts to 75 mph.	South 20 to 35 mph with gusts to 75 mph.
Expected snowfall:	Up to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability of 1 to 4 inches. 10% probability up to 1 inch. \| SWE = up to 0.15 inch. in.	80% probability of 7 to 13 inches. 20% probability of 3 to 7 inches. \| SWE = 0.55-0.80 inch. in.

Over 10,000 ft.

	Tuesday	Tuesday Night	Wednesday
Weather:	Mostly cloudy. Chance of snow through the day. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 30%.	Mostly cloudy. Chance of snow through the night. Snow levels 7500 feet. Chance of precipitation is 40%.	Cloudy. Snow in the morning, then snow showers in the afternoon. Snow levels 7000 feet. Chance of precipitation is 100%.
Temperatures:	27 to 33. deg. F.	18 to 23. deg. F.	22 to 28. deg. F.
Ridge Top Winds:	Southwest 30 to 45 mph with gusts to 70 mph.	Southwest 30 to 50 mph. Gusts up to 65 mph increasing to 90 mph after midnight.	Southwest 35 to 55 mph with gusts to 90 mph.
Expected snowfall:	Up to 2 inches. \| SWE = less than 0.10 inch. in.	90% probability of 1 to 4 inches. 10% probability up to 1 inch. \| SWE = up to 0.15 inch. in.	90% probability of 8 to 14 inches. 10% probability of 4 to 8 inches. \| SWE = 0.50-1.00 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.