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Avalanche Advisory for 2017-12-30 06:06:56

  • EXPIRED ON December 31, 2017 @ 6:06 am
    Published on December 30, 2017 @ 6:06 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest
  • December 30, 2017 @ 6:06 am

    Advisory Hotline: (530) 926-9613

  • LOW avalanche danger and normal caution continue. Generally safe avalanche conditions exist. Sparse coverage and firm and icy slopes present significant travel hazards on Mt Shasta. 

  • 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

Normal caution is advised. The firm, icy, and thin snowpack continues to create backcountry travel hazards. Moving through steep terrain above treeline is challenging and dangerous. Arresting a fall in these conditions would be difficult. Watch out for rocks. Low angle slopes with smooth ground cover offer the best skiing and riding conditions.

  • Ski and ride one at a time in avalanche terrain.
  • Don’t regroup in run-out zones.
  • Avalanche rescue skills are always essential when you travel in avalanche terrain.


Advisory Discussion

The broken record is badly broken. While no day is ever the same, the snow and weather have stayed close. A re-cap of our season thus far: October and November storms laid a shallow snowpack at high elevations on Mount Shasta. During Thanksgiving week, it rained up to 10,000ft. This rain event was followed by cold and clear weather which capped the snow surface at 7,000ft and above with a crust, while below, it eliminated any existing snow on the ground. We have had two small storm events this December totaling 10 inches of snow and less than 1 inch of water. Otherwise, high pressure has dominated our weather pattern. Precipitation is well below average, and a large portion of our advisory area is free of snow.  Mt Shasta and Ash Creek Butte are the only areas with a (barely) usable snowpack. A warm storm system with modest precipitation is not expected until the first week of January. This weekend will be mostly sunny and westerly winds should die off by Sunday.


Recent Observations

The snowline slowly creeps upward. Very little coverage exists below 6,500ft. The height of snow ranges from 30-100cm between 6,500-9,500ft. The rain crust that formed on Thanksgiving continues to lock up the lower snowpack. This slick, icy layer is the primary snow surface near and above treeline. North and east aspects below treeline, 20-25cm of recycled powder (the December 3rd and December 20th storms) exists at the snow surface.  South and some west aspects, near and above treeline, patches of corn snow can be found. Snowpack stability is very good throughout the advisory area. Rocks, down trees, small tree tops and bushes are widespread.


Weather and Current Conditions

Weather Summary

A weak warm front is stetched across the forecast area this morning with Mt Shasta out of it's main grip. A few light showers might be seen this morning on the mountain with little to no accumulation. Dry air will descend over the area today, skies will clear and the strong westerly winds will die down above treeline.  High temps won't be as warm in most places. The short term forecast is uneventful. Chances of precipitation increase later in the first week of January. At this point, conflicting weather models suggest meager precip amounts and high snow levels...not exactly music to our ears. In a couple days, we will have a better idea on the details.

CLICK HERE for information from the NOAA Climate Prediction Center


THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 5.83 inches of water, normal is 14.70 inches, putting us at 39% of normal. For the month of December, we have received .29 inches of water, normal is 7.34 inches, which is 3% of normal. And finally for the year of 2017, we received 44.82 inches of water, normal is 42.70 inches, putting us at 104% of normal.

Always check the weather before you attempt to climb Mt 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) 26 26 56 35 1 N
Sand Flat (6750 ft) 38 32 49 39 15 0 0 0
Ski Bowl (7600 ft) 39 35 49 41 19 0 0 0
Grey Butte (8000 ft) 35 33 44 39 20 43 WNW
Castle Lake (5870 ft) 43 40 49 44 9 0 0
Mount Eddy (6509 ft) 39 37 53 44 2 7 WSW 11 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
  Saturday Saturday Night Sunday
Weather Chance of showers before 10am, otherwise clearing, partly sunny Partly cloudy Mostly sunny
Temperatures 47 deg. F. 35 deg. F. 47 deg. F.
Wind direction West East South
Wind speed 5-10 mph 5 mph 0-5 mph
Expected snowfall 0 in. 0 in. 0 in.
For 9000 ft to 11000 ft
  Saturday Saturday Night Sunday
Weather Chance of showers before 10am, otherwise clearing, partly sunny, windy Partly cloudy, windy Mostly sunny
Temperatures 33 deg. F. 33 deg. F. 34 deg. F.
Wind direction West West Southwest
Wind speed 30-40 mph, gusts higher 15-20 mph 5-10 mph
Expected snowfall 0 in. 0 in. 0 in.


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.