You are here

Avalanche Forecast for 2019-12-12 06:13

  • EXPIRED ON December 13, 2019 @ 6:13 am
    Published on December 12, 2019 @ 6:13 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

While not expected to pose a major concern, remain attentive to small, isolated wind slabs above treeline on S-SE-E-NE aspects from a few inches of fresh snow and strong W/SW wind.  Expect MODERATE danger above treeline and generally LOW danger near and below treeline on Mount Shasta. Other areas within the forecast area still host shallow snowpack conditions.

 

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

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

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

Forecast Hotline: (530) 926-9613

Avalanche Problem 1: Wind Slab

  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Small, isolated wind slabs may be encountered above treeline on Mount Shasta, primarily on easterly facing aspects. West/Southwest winds have been and will continue to be strong enough to transport freshly fallen snow. Wind slabs may not be large enough to bury a backcountry user, but could cause one to loose their balance and initiate a fall. Look for blowing snow, cornice formation and surface scouring as clues to where new wind slabs might exist.

Forecast Discussion

A nice looking jet stream delivering spurts of wet weather over the next couple days. Significant snow accumulation is not expected unfortunately, but something is better than nothing! West/Southwest wind and bits of new snow may contribute to small wind slab formation. Life threatening avalanche danger is not expected, though always use safe travel practices (one at a time in avalanche terrain; don't regroup in run out zones) and look for red flags of avalanche danger such as recent avalanches, wind blowing snow, cracking or collapsing in the snowpack.

Recent Observations

Submit Snowpack Observations
Submit Avalanche Observations
  • In the last 24 hours at treeline on Mount Shasta, temperatures have ranged from 25 to 30°F with average wind speeds of 13 mi/hr, gusts to 25 mi/hr out of the west/southwest.
  • Precipitation began at 1300 hours yesterday and persisted until midnight last night. Snow struggled to accumulate with only about 1 to 2 inches of new snow at 8,000 feet. Snow levels were near Sand/Bunny Flat area, 6,500 to 7,000 feet.
  • Snow surfaces have been generally smooth albeit variable - soft, thin wind crusts, breakable sun crusts, and wind affected chalk. Start zones have smooth, crusty bed surfaces. 
  • Hazards still lurk beneath the snow surface.
  • No red flags or other signs of instability have been encountered.

Weather and Current Conditions

Weather Summary

A northern hemispheric pattern shows a wave number of 4 to 5 around the globe, which usually indicates a progressive weather pattern. The jet stream is directly focused on Northern California and Southern Oregon. This will bring a continued series of quick moving systems onshore in rapid succession. The Cascades should see 1.5 to 3 inches of water all said and done. Snow levels will lie near 6,500 feet today, lowering to 5,500 feet tonight and tomorrow...thus a few inches of snow here and there over the course of the next couple days. Wind will be a factor in higher terrain. Gusty south/southwest winds up to 40 mi/hr can be expected this afternoon, especially in the Shasta Valley. Saturday will bring cooler air, though precipitation will diminish.

24 Hour Weather Station Data @ 4:00 AM

Weather Station Temp (°F) Wind (mi/hr) Snow (in) Comments
Cur Min Max Avg Avg Max Gust Dir Depth New Water Equivalent Settlement
Mt. Shasta City (3540 ft) 39 29 43 36 2 N
Sand Flat (6750 ft) 33 29 33 31 30 1 n/a 0
Ski Bowl (7600 ft) 30.5 25.5 30.5 27.5 40.6 1.7 0.34 1.3
Gray Butte (8000 ft) 29 24.5 29.5 26.5 13 25 W
Castle Lake (5870 ft) 0 0 0 0 0 0 0 down
Mount Eddy (6509 ft) 34 28 34.5 31 2 12 SSE 27 1 0
Ash Creek Bowl (7250 ft) down
Ash Creek Ridge (7895 ft) down

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Thursday
(4 a.m. to 10 p.m.) 		Thursday Night
(10 p.m. to 4 a.m.) 		Friday
(4 a.m. to 10 p.m.)
Weather Rain and snow, breezy, chance of precipitation 90%. Snow levels near 6,500 feet. Snow showers, chance of precipitation 90%. Snow levels near 6,500 feet, lowering to 5,500 feet. Snow showers, breezy, chance of precipitation 100%. Snow levels near 5,500 feet.
Temperature (°F) 36 29 33
Wind (mi/hr) Southwest 20-25 Southwest 10-15 Southwest 10-15
Precipitation SWE / Snowfall (in) 0.24 / 0-1 0.04 / 1-2 0.38 / 3-5
For 9000 ft to 11000 ft
  Thursday Thursday Night Friday
Weather Snow, windy. Wind chill values as low as -12 F. Chance of precipitation 90%. Snow showers, windy. Wind chill values as low as -13 F. Chance of precipitation 90%. Snow showers, windy. Wind chill values as low as -10 F. Chance of precipitation 100%.
Temperature (°F) 19 16 20
Wind (mi/hr) West 35-40 West 30-35 West 30-35
Precipitation SWE / Snowfall (in) 0.24 / 3-5 0.04 / 2-4 0.38 / 4-8

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2024 (the wet season) 7.77 9.93 78
Month to Date (since Dec 1, 2024) 5.09 2.57 198
Year to Date (since Jan 1, 2024) 45.51 37.93 120

Disclaimer

This forecast does not apply to Ski Areas or Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy backcountry. Use this information for guidance only. You may find different conditions in the backcountry and should travel accordingly. This forecast expires 24 hours after the posted time unless otherwise noted.