Avalanche Advisory: Tuesday - Mar 10, 2020

THIS AVALANCHE ADVISORY EXPIRED ON March 11, 2020 @ 6:36 am
Avalanche Advisory published on March 10, 2020 @ 6:36 am
Issued by Steve Mace - ESAC

LOW avalanche danger persists today at all elevations. Isolated areas of wind slab may exist on NW-N-E-SE aspects at Upper and middle elevations. Extreme terrain such as couloirs and unsupported slopes adjacent to cliff bands and rock outcroppings deserve extra consideration. Moderate winds and a chance of new snow today may lead to increased wind slab hazard by this evening.  It is possible the danger may rise to MODERATE near and above treeline by tomorrow morning if we see snow totals at the high end of the forecast.

1. Low

?

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

1. Low

?

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

1. Low

?

Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Moderate SW winds today will continue to transport and redistribute loose surface snow and may lead to fresh wind slab development on northerly aspects near and above treeline.  While triggering an avalanche large enough to bury a person is unlikely, small isolated areas of unstable snow may exist in extreme or complex terrain. Even a small avalanche today could prove to be consequential if it occurs in exposed or confined terrain. Field observations have observed high variability in the distribution of fresh wind deposits from the storm last Saturday, which brought 1-4” of new snow. Exposed leeward catchment zones, convex and unsupported slopes, and cross-loaded gully features near and above treeline deserve extra consideration. Keep an eye out for blowing snow today. Fresh drifts, uneven snow surface, and recent cornice growth are all clues that indicate nearby wind deposits. Do your own localized assessments and be suspect of terrain features that encourage drifting. 

Expect the Size and distribution of fresh wind slabs to increase this evening if we receive new snow totals on the high end of the forecast. This will be more likely in areas north on Mammoth, which may see up to 5” of snow overnight.

advisory discussion

While the brief storm last weekend and continued cold temperatures have led to improved riding conditions, overall coverage remains quite thin, and contiguous panels of snow are fleeting. This is particularly true on solar aspects and at lower elevations. Despite the recent addition of new snow thin coverage and variable surface conditions remain a significant hazard. Be wary of shallowly buried obstacles like rocks and fallen trees.  Move cautiously through terrain and be ready to encounter a wide variety of surface conditions.

Weather and CURRENT CONDITIONS
weather summary

We can expect to see mostly cloudy skies and increasing southwest winds today as a low-pressure system moves into the area. Temperatures will be near freezing today at mid-elevations. There is a chance of snow this afternoon and into the evening accompanied by moderate SW winds. Precipitation totals are not likely to be significant for much of the forecast area but areas north of mammoth may see up to 5” of snow by tomorrow morning. 

More quiet weather is on tap for the rest of the week with warming temperatures expected before the weekend.  Chances are good for another low-pressure system late this weekend or early next week that may bring more significant snowfall and strong winds.

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: Partly cloudy then becoming mostly cloudy. Chance of snow. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 35%. Mostly cloudy. Snow likely. Snow levels 7500 feet. Chance of precipitation is 50-60%...except 80% south of Tioga Pass. Mostly cloudy. Chance of snow. Snow levels 7500 feet. Chance of precipitation is 45%.
Temperatures: 34 to 44. deg. F. 26 to 32. deg. F. 36 to 44. deg. F.
Mid Slope Winds: Light winds becoming southeast around 15 mph in the afternoon. Gusts up to 30 mph. Southeast around 15 mph with gusts to 35 mph. Light winds.
Expected snowfall: 40% probability up to 1 inch. 60% probability no accumulation. | SWE = trace amounts. in. 70% probability up to 2 inches. 30% probability of 2 to 4 inches. | SWE = up to 0.25 inch. in. up to 1 inch. | SWE = less than 0.10 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 40%. Mostly cloudy. Snow likely. Snow levels 7500 feet. Chance of precipitation is 50-60%...except 85% south of Tioga Pass. Mostly cloudy. Chance of snow. Snow levels 7500 feet. Chance of precipitation is 50%.
Temperatures: 25 to 33. deg. F. 21 to 27. deg. F. 27 to 35. deg. F.
Ridge Top Winds: East 15 to 25 mph with gusts to 35 mph. East 15 to 30 mph with gusts to 40 mph. Northeast 15 to 20 mph with gusts to 35 mph.
Expected snowfall: 40% probability up to 1 inch. 60% probability no accumulation. | SWE = less than 0.10 inch. in. 60% probability of 1 to 3 inches. 40% probability of 3 to 5 inches. | SWE = up to 0.25 inch. in. up to 1 inch. | 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.

ESAC receives significant financial support from ...