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Avalanche Advisory for 2017-01-16 07:03:12

  • EXPIRED ON January 17, 2017 @ 7:03 am
    Published on January 16, 2017 @ 7:03 am
  • Issued by Andrew Kiefer - Mt Shasta Avalanche Center

LOW avalanche danger exists in the backcountry on all aspects and at all elevations.  A wind slab problem remains the primary concern near and above treeline.  Natural and human-triggered avalanches are unlikely.  LOW danger does not mean that no danger exists.  Continue to evaluate the snowpack, and 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.

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

Avalanche Problem 1: Wind Slab

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

Wind slabs have the potential to exist on all aspects near treeline and above treeline.  Natural and human triggered wind slab avalanches are unlikely.  The wind slab problem exists in isolated areas, and has become stubborn to trigger.  Unsupported terrain features, gullies, couloirs, and rocky outcrops near cliff bands are the areas where the wind slab problem is most likely to be encountered.  Avoid these steep and complex terrain features that hold wind-loaded snow.   Practice good travel techniques, and only expose one skier or rider at a time to avalanche terrain.  Regroup in islands of safety, and be aware of what is above you and below you.  Use visual observations to identify the wind slab problem.

Forecast Discussion

The snowpack continues to consolidate and show signs of improving stability.  The most recent avalanche activity occurred several days ago during last week’s storm.  Lingering wind slabs remain the primary concern, and snowpack assessment should target this problem.  Cornices are becoming unreactive, but still exist on ridgelines and exposed terrain features.  Continue to identify and avoid these unpredictable snow formations.  Upper elevation (>10,000 feet) terrain still holds the greatest potential for avalanches.  With warm temperatures expected today, isolated loose wet instabilities are possible on sun-exposed slopes.  This problem is not expected to cause significant concern for backcountry users.

Recent Observations

Beautiful, sunny weather continued yesterday throughout the advisory area.  Highs reached the low 40’s, and winds were calm.  A tour on Grey Butte revealed no signs of recent avalanche activity, consolidation of the snowpack, and good stability.  Lingering wind slabs and cornices found in the area all formed during our last storm, and appeared unreactive, or very stubborn to trigger.  Several old and large cracks within the cornice formations were found along ridge top, but it has been several days since any cornice failure has occurred.  Snow surfaces were variable.  Northerly shady slopes above 6000ft continue to hold dry, cold powder.  The sun has significantly affected southerly slopes, and both supportable and breakable crusts exist.  Westerly aspects are variable, and wind affected snow is easy to find.  Skiers ventured high on the east side of Mt. Shasta yesterday and found firm conditions and wind scoured snow in upper elevations.  Middle and low elevations revealed good skiing and soft, cold snow in wind-protected areas.

 

Weather and Current Conditions

Weather Summary

A major pattern change is in store for this week, as a quiet high-pressure ridge transitions to another active, high impact series of storms.  For MLK Day today, dry weather will continue, and skies will be mostly sunny with highs in the mid 40's to lower 50's at the 6000ft level.  Winds will blow out of the northeast at 5-10mph.  Freezing levels will range from 7000-8000ft, and skies will become partly cloudy tonight and tomorrow. Southerly flow will move in place by Tuesday evening.  Precipitation is expected to begin by Wednesday morning, and a mix of rain and snow will continue through the end of the week.

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In Mt Shasta City at 0500, we have a current temperature of 30 F.

On Mt Shasta (South Side) in the last 24 hours...

Old Ski Bowl - 7,600 feet, the current temperature is 33 degrees F.  Temperatures have ranged from 26 F to 40 F. Snow on the ground totals 111 inches with a no new snow and 1 inch of settlement

Grey Butte - 8,000 feet, the current temperature is 37 degrees F. Temperatures have ranged from 33 F to 41 F.  Winds have averaged 5-10 mph with gusts to 21mph, blowing out of the northwest.

Mt Eddy Range (West side of Interstate-5)... 

Castle Lake - 5,600 feet, the current temperature is 30 degrees F. Temperatures have ranged from 22 F to 34 F. Snow on the ground totals 53 inches with no new snow and 1 inch of settlement.

Mt Eddy - 6,500 feet, the current temperature is 41 degrees F. Temperatures have ranged from 32 F to 42 F. Snow on the ground measures 58 inches with no new snow and 2 inches of settlement.  Winds have averaged 2-4 mph with gusts to 16 mph, blowing out of the west/southwest.

THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 28.27 inches of water, normal is 18.81 inches, putting us at 150% of normal.  For the month of January and for the year of 2017, we received 7.11 inches of water, normal is 3.60 inches, putting us at 196% 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.

CURRENT CONDITIONS at Bunny Flat (6950 ft)
0600 temperature: 22
Max. temperature in the last 24 hours: 33
Average wind direction during the last 24 hours: Northwest
Average wind speed during the last 24 hours: 0-5 mi/hr
Maximum wind gust in the last 24 hours: 10 mi/hr
New snowfall in the last 24 hours: 0 inches
Total snow depth: 62 inches

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Monday
(4 a.m. to 10 p.m.)
Monday Night
(10 p.m. to 4 a.m.)
Tuesday
(4 a.m. to 10 p.m.)
Weather Mostly Sunny Partly Cloudy Increasing Clouds
Temperature (°F) 46 34 44
Wind (mi/hr) East/Northeast 10-15 Northeast 5-10 South 15-20 mph
Precipitation SWE / Snowfall (in) / 0 / 0 / 0
For 9000 ft to 11000 ft
  Monday Monday Night Tuesday
Weather Mostly Sunny and Windy Partly Cloudy Increasing Clouds and Windy
Temperature (°F) 34 33 34
Wind (mi/hr) North 20-25 mph West 0 West/Southwest 30-35 mph
Precipitation SWE / Snowfall (in) / 0 / 0 / 0

Disclaimer

This advisory 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 advisory expires on midnight of the date it was posted unless otherwise noted.