THIS AVALANCHE FORECAST EXPIRED ON March 28, 2019 @ 7:00 am
Avalanche Forecast published on March 27, 2019 @ 7:00 am
Issued by Steve Reynaud - Tahoe National Forest

CONSIDERABLE avalanche danger will exist at all elevations due to wind slab, storm slab, and loose wet avalanche problems.  A storm will bring heavy snow to our forecast area today and tonight.  Human triggered avalanches are likely with natural triggered avalanches possible.

3. Considerable

?

Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

?

Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

?

Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Wind slab avalanches will be likely today on NW-N-NE-E-SE aspects in near and above treeline terrain.  Gale force SW winds will transport new snow and create large wind slabs today in wind exposed areas.  Wind slab development may also be possible on other aspects or in below treeline areas with ridge wind gusts near 100mph.

Avoid steep wind loaded terrain and areas near or below wind loaded slopes and cornices.  Widespread blowing snow is expected in all but the most protected below treeline areas.   

Avalanche Problem 2: Storm Slab
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Storm slab avalanches will be likely on all aspects in near and below treeline terrain.  1 to 2 feet of new snow is forecasted to fall by tonight or early Thursday morning.  Storm slab weakness could occur within the new storm snow or at the old snow/new snow interface.  Storm slabs could have wet slab characteristics as daytime warming and the potential for rising snow levels occurs today.

Look for cohesion of the new storm slabs or heavier snow over lighter snow.  Cracking or collapsing will indicate potential weakness within the new storm slab.  Utilize lower angle terrain to help limit exposure to steeper slopes.

Avalanche Problem 3: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

As daytime warming occurs today along with the potential for rising snow levels, loose wet avalanches will become likely on all aspects.  Depending on warming, most loose wet avalanche activity should be limited to areas below 7500'.  Loose wet avalanches could involve the current storm snow and also the recent storm snow that sits on top of an old surface crust.  Roller balls and pinwheels will be an indicator that the surface snow is decreasing in strength and larger loose wet avalanches could occur.   

  

recent observations

*  More sun was seen on Hidden Peak (West Shore area) with a poor overnight refreeze of the snow surface.  Small loose wet avalanches (D1) involving the top 2-3'' of snow were easy to trigger on steeper slopes between 8400-6800' range.

*  Warm conditions existed on Silver Peak (Pole Creek area) with 2-3'' of new snow above 8000'.  Small roller balls occurred while down skiing with light rain below 6800'. 

*  Observations from Trimmer Peak (Luther Pass area) showed a variety of snow surfaces with little signs of instabilities.

Weather and CURRENT CONDITIONS
weather summary

A winter storm warning remains in effect until 11pm tonight.  The general timing of this storm has slowed and should start to ramp up in the Tahoe Basin by 6am this morning.  Heavier snow is expected in the late afternoon into evening hours.  1 to 2' of snow is still forecasted along the Sierra Crest by late tonight/early Thursday morning.  Snow levels should remain near 7000', although they have been as high as 7500' overnight.  Gale force SW winds will continue with ridge gusts near or exceeding 100mph.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 28 to 32 deg. F.
Max. temperature in the last 24 hours: 29 to 37 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 50 to 80 mph
Maximum wind gust in the last 24 hours: 116 mph
New snowfall in the last 24 hours: 0 to 1'' snow, .10 to .40'' rain inches
Total snow depth: 109 to 156 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 100%. Cloudy then becoming partly cloudy. Snow showers in the evening, then chance of snow showers after midnight. Snow levels below 7000 feet. Chance of precipitation is 95%. Partly cloudy then becoming mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 55%.
Temperatures: 31 to 36. deg. F. 19 to 24. deg. F. 27 to 33. deg. F.
Mid Slope Winds: Southwest 20 to 30 mph with gusts to 70 mph. Southwest 15 to 25 mph with gusts to 55 mph. Southwest 15 to 25 mph with gusts to 40 mph.
Expected snowfall: 80% probability of 6 to 12 inches. 20% probability of 12 to 17 inches. | SWE = 0.55-1.05 inches. 80% probability of 4 to 8 inches. 20% probability of 2 to 4 inches. | SWE = 0.20-0.45 inch. Up to 2 inches. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Cloudy. Snow. Snow levels 7000 feet. Chance of precipitation is 100%. Mostly cloudy. Snow showers in the evening, then chance of snow showers after midnight. Snow levels below 7000 feet. Chance of precipitation is 100%. Partly cloudy then becoming mostly cloudy. Chance of snow showers. Snow levels below 7000 feet. Chance of precipitation is 55%.
Temperatures: 28 to 33. deg. F. 15 to 20. deg. F. 23 to 28. deg. F.
Ridge Top Winds: Southwest 30 to 50 mph with gusts to 105 mph. Southwest 25 to 40 mph with gusts to 80 mph. Southwest 20 to 30 mph with gusts to 60 mph.
Expected snowfall: 80% probability of 9 to 15 inches. 20% probability of 15 to 20 inches. | SWE = 0.65-1.10 inches. 80% probability of 4 to 10 inches. 20% probability of 2 to 4 inches. | SWE = 0.30-0.55 inch. Up to 2 inches. | SWE = less than 0.10 inch.
Disclaimer

This avalanche forecast is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This forecast covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. This forecast applies only to backcountry areas outside established ski area boundaries. This forecast describes general avalanche conditions and local variations always occur. This forecast expires 24 hours after the posted time unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the avalanche forecast call (530) 587-3558 x258