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Avalanche Advisory for 2018-01-11 06:26:50

  • EXPIRED ON January 12, 2018 @ 6:26 am
    Published on January 11, 2018 @ 6:26 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

LOW avalanche danger exists at all elevations. Isolated wind slabs may exist above 9000 ft on N-NE-E-SE-S aspects. Be aware of falling rime ice. Wear a helmet. Smooth, firm snow surfaces exist on some slopes. A long slide for life is possible without immediate self arrest. Know how to use your ice axe and crampons.

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: Wind Slab

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    Very Likely
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Strong winds were transporting snow above 9000 ft yesterday on Mount Shasta. Wind loading is likely on N-NE-E-SE-S aspects. LOW avalanche danger does not mean NO avalanche danger. Monitor changing conditions if ascending above 9000 ft. Look for cornice formation and shooting cracks in drifted snow as evidence of the wind slab problem. If in doubt, avoid convex slopes greater than 35 degrees. Look at connected terrain and consider the consequences of being carried down hill by a small avalanche.

Advisory Discussion

The snowpack below 9000 ft is locked up tight. Above, the wind slab problem is a small concern, but one to take seriously. The rime ice plastered on the crags of ridges continues to be a hazard. Warming temperatures will cause this ice to dislodge and plummet down upon skiers and climbers in the coming days. Wear a helmet. Hard chunks of ice can function just like a rock. 

Mt Shasta is the only zone within the forecast area that holds a usable snowpack for winter recreation at this time. Castle Lake and The Eddy Mountains as well as much of the areas east of Mt Shasta are snow free or very thin.

Recent Observations

Continued trouble shooting on the Ash Creek Butte weather station brought us out to the east side yesterday. Pilgrim Creek Snowmobile Park is still snowless. One is able to drive all the way to the Brewer Creek trailhead turnoff, off Military Pass road, and beyond with a good 4WD vehicle (muddy). Approximately 1 inch (2.5cm) new snow was on roadway at this point. Up on the Ash Creek Loop road (snowmobiles), a tad more new snow was observed, 2-3 inches (5-7cm). Patches of bare road existed in some areas. We don't advise riding out here currently. Winds aloft could be heard below treeline. Near and above treeline, gusty winds were blasting all day, 25-35 mph out of the west/northwest. Giant plumes of blowing snow were visible above 9,000 feet on Mt Shasta through a few brief doughnut holes in the clouds. The minimal amount of new snow was too moist below and near treeline to experience wind transport. Some slopes held a thin zipper crust. Mostly cloudy skies and low fog was the trend for the day. We did not observe any signs of instability or recent avalanches in the Ash Creek Butte area. We were not able to sight any recent crown lines on the east side of Mt Shasta either. Temperatures have warmed a bit this morning and daytime highs will be even warmer this weekend.

Weather and Current Conditions

Weather Summary

The second of two weak frontal systems will move across the area today bringing a touch of precipitation. We could see up to a tenth of an inch of water. Temperatures have warmed and snow levels will hover near 7,100 feet. Most notable are high winds out of the west, near and above treeline. Steady speeds of 35 mph with gusts up to 50 mph are expected, especially in exposed areas, along ridge lines and the upper mountain. Friday, weather will begin to clear and sunny skies will commence the weekend as a ridge of high pressure sets up, bringing warmer temps. Next week, everyone is getting excited from murmurs of wet, unsettled weather lasting through the week and perhaps beyond. Wax'em and gas'em...we are getting excited too.  

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THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 7.81 inches of water, normal is 17.60 inches, putting us at 44% of normal. For the month of January and 2018, we have received 1.98 inches of water, normal is 2.39 inches, which is 82% of normal. 

Always check the weather before you attempt to climb Mount Shasta. Further, monitor the weather as you climb. Becoming caught on the mountain in any type of weather can compromise life and limb. Be prepared.

24 Hour Weather Station Data @ 5:00 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) 41 36 44 40 1 N
Sand Flat (6750 ft) 33 27 36 33 11 0 0 1
Ski Bowl (7600 ft) 33 23 36 32 24 0 0 0
Gray Butte (8000 ft) 31 22 36 30 24 49 NW
Castle Lake (5870 ft) 38 28 40 35 0 0 0
Mount Eddy (6509 ft) 38 26 39 33 2 11 WSW 0 0 0
Ash Creek Bowl (7250 ft) Station down
Ash Creek Ridge (7895 ft) Station down

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Thursday Thursday Night Friday
Weather Mostly cloudy with a 30% chance of snow. Mostly cloudy with a 30% chance of rain and snow showers Mostly cloudy with a 20% chance of rain and snow showers in AM, then partly cloudy in PM.
Temperature (°F) 40 31 44
Wind Direction South Southwest South
Wind Speed (mi/hr) 10-15 mph 10-15 mph 0-5 mph
Expected Snowfall (in) <.5 <.5 0
For 9000 ft to 11000 ft
  Thursday Thursday Night Friday
Weather Mostly cloudy, 60% chance of snow, mainly after 10am, windy 50% chance of snow showers, mostly cloudy, windy Chance of snow showers in AM, clearing to partly cloudy, windy
Temperature (°F) 27 23 32
Wind Direction West West West
Wind Speed (mi/hr) 35-45 mph 40-50 mph 20-30 mph
Expected Snowfall (in) 1-2 1-2 0

Disclaimer

This advisory does not apply to Ski Areas or Highways and is for the Mount Shasta, Castle Lake and Mount Eddy backcountry. Use this information for guidance only. You may find different conditions in the backcountry and should travel accordingly. This advisory expires on midnight of the date it was posted unless otherwise noted.