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Avalanche Forecast for 2021-04-04 06:40

  • EXPIRED ON April 5, 2021 @ 6:40 am
    Published on April 4, 2021 @ 6:40 am
  • Issued by Ryan Sorenson - Mount Shasta Avalanche Center

Spring has sprung, and the climbing season has begun. Increased rockfall and concern for other climbing-related hazards such as slips and falls on smooth icy surfaces have moved to the top of the list. Springtime avalanche problems are still on the radar as well. Watch for loose wet avalanches on warming sunlit slopes, especially on long steep slopes that could entrain enough wet snow or areas with terrain traps. 

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

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: Normal Caution

  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Very Likely
  • Size ?
    Very Large

Clear skies and cool temperature likely allowed a decent refreeze last night. Expect the spring sun to melt through this fast today. Watch for sluffs of wet loose snow on steep, sunlit slopes. Loose, wet snow that begins sliding downhill can gather more wet snow as it moves. Traditional pit tests don't work for loose-wet slides, but rollerballs, pinwheels, and wet, sticky, ankle-deep snow are signs to watch for. Loose-wet slides are usually slow-moving and too small to cause major problems for backcountry travelers. Still, long steep slopes that could entrain enough wet snow or areas with terrain traps should be approached cautiously during the hottest hours of the day.  

Forecast Discussion

The pictures are most telling, but if you haven't heard yet, we've had dry winter that is 48% of normal for precipitation and accompanied by A LOT of wind. The mountain above the treeline is a scoured, rocky heap, and climbs this season will host more risk than normal. The optimal climbing season has been pushed months earlier this year. If you plan to climb the south side of Mount Shasta, now is the time. The climbing routes around The Heart and through the Redbanks in Avalanche Gulch are already narrow and/or melted out. If ascending anywhere below exposed rocks, keep your head up and helmet on! 

The Bunny Flat trailhead is the only open trailhead accessible by vehicle at this time. We will post photos and information regarding other trailheads and routes as access is gained. Except for Bunny Flat, all summit passes, wilderness permits, and human waste packout bags must be attained at the McCloud or Mt. Shasta Ranger Stations (self-issue) or at The Fifth Season in Mt. Shasta.

Avalanche Gulch from yesterday, 4.3.21 [Photo: Sorenson]

Recent Observations

Mixed high altitude clouds, a few lens-shaped, hung above Mount Shasta yesterday, keeping things gray.  This slightly delayed snow surfaces' softening, but the warm spring temperature had conquered by mid-afternoon, and snow surfaces at lower elevations turned sicky, moist, and heavy. Reports from local spring skiers were in the mediocre to acceptable range. Rockfall is still a major concern on the upper mountain. Climbers reported numerous falling golfball to baseball-sized rocks above Lake Helen yesterday morning.  Strong westerly winds kept snow surfaces firm at upper elevations. No recent avalanches have been observed.

Over the past 24 hours, temperatures at our Old Ski Bowl weather station have averaged 41.5 °F, with a 33.5 °F low and a 50 °F high. Winds on Gray Butte averaged 7 mi/hr, maxed out at 12 mi/hr and a minimum of 5 mi/hr, predominantly out of the west/southwest. An average depth of 66 inches (170 cm) was measured at the Sierra Alpine Hut (Horse Camp). A snow depth of 62-64 remains over on the west side in the Castle Lake Basin and Eddy Mountains. 

Snow surfaces near the Red Banks yesterday morning, 4.3.2021

Weather and Current Conditions

Weather Summary

Spring has sprung, and sunny skies will prevail. A similar story to most of the days this winter will play out again. Low pressure moving close to the area will allow some clouds and wind to filter through late this evening, but high pressure will block the moisture from reaching Mount Shasta. Expect clear skies, then increasing clouds this evening. After that, dry and mild conditions will linger throughout the week and into the foreseeable future. 

24 Hour Weather Station Data @ 3:00 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) 35 34 67 50.5 1 N
Sand Flat (6750 ft) 32 32 52 42 Snow sensor down
Ski Bowl (7600 ft) 33 33 50 41 72.8 0 0 1.7
Gray Butte (8000 ft) 34.5 34.5 44 39.5 7 31 SW
Castle Lake (5870 ft) 37 36.5 58 46.5 62 0 0.5
Mount Eddy (6509 ft) 34 34 49.5 43 2 5 S 62 0 0.8
Ash Creek Bowl (7250 ft) 33 14 33 23.5 69.4 0 0.5
Ash Creek Ridge (7895 ft) 34.5 34 41.5 37.5 16 31 S

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
(4 a.m. to 10 p.m.)
Sunday Night
(10 p.m. to 4 a.m.)
(4 a.m. to 10 p.m.)
Weather Sunny Partly cloudy Sunny
Temperature (°F) 56 30 44
Wind (mi/hr) South 5-10 West 5-10 Northwest 5-10
Precipitation SWE / Snowfall (in) 0.00 / 0 0.00 / 0 0.00 / 0
For 9000 ft to 11000 ft
  Sunday Sunday Night Monday
Weather Sunny and windy Partly cloudy and windy Sunny and windy
Temperature (°F) 33 26 30
Wind (mi/hr) Southwest 20-30 West 20-30 Northwest 40-45
Precipitation SWE / Snowfall (in) 0.00 / 0 0.00 / 0 0.00 / 0

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2022 (the wet season) 17.15 35.81 48
Month to Date (since Jun 1, 2023) 0.00 0.35 0
Year to Date (since Jan 1, 2023) 13.57 20.60 66


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.