Avalanche Advisory published on March 27, 2017 @ 6:50 am
This Avalanche Advisory expires in 3 hours, 2 minutes
This advisory is valid for 24 hours
Issued by Andrew Kiefer - Mt Shasta Avalanche Center
bottom line

The avalanche danger is MODERATE near treeline and above treeline.  Wind slabs exist in leeward terrain, primarily on S-SE-E-NE-N aspects. Precipitation will taper off by the early afternoon, but steady, westerly winds will continue. Watch for blowing snow and fresh wind slab development throughout the day. The avalanche danger is LOW below treeline.      

How to read the advisory


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

2. Moderate

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Above Treeline

2. Moderate

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Near Treeline

1. Low

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Below Treeline

The avalanche danger is MODERATE near treeline and above treeline.  Wind slabs exist in leeward terrain, primarily on S-SE-E-NE-N aspects. Precipitation will taper off by the early afternoon, but steady, westerly winds will continue. Watch for blowing snow and fresh wind slab development throughout the day. The avalanche danger is LOW below treeline.      

  • Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Wind Slab
  • Character ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Westerly winds have blown throughout the recent storm series, creating wind slabs near and above treeline. S-SE-E-NE-N facing aspects above the 8000ft level are the areas where the wind slab problem is most likely to be found.  Moderate to strong northwest winds are expected today, and wind slabs will continue to grow in size and distribution.  Watch for blowing snow, cornice formation, and textured snow surfaces to help identify lee slopes and cross-loaded terrain features.  Avoid wind-loaded slopes 35 degrees and steeper.

 

recent observations

Above the 6000ft level, 4-6 inches of new snow fell over the past 24 hours.  The recent snowfall has been paired with a cooling trend, and overnight lows were near 20 degrees F at all of our remote weather stations.  Westerly winds have blown over the past 72 hours, and have organized to the northwest overnight with gusts near 35 mph.

The south side of Mount Shasta experienced light snowfall throughout the day yesterday with very limited visibility in the alpine.  Snow levels were near 5000ft.  The upper snowpack presents 30-40 inches of well bonded, settled snow received over the past week with no significant layers of concern.  There are several melt-freeze crusts within the upper layers snow, the most recent of which formed on Saturday.  Four to five inches of new snow sat atop this most recent and supportable crust yesterday in areas between 7000-9000ft.  Blowing snow was observed near and above treeline, and easterly aspects were actively loading throughout the day.   

CURRENT CONDITIONS Weather observations from Bunny Flat
0600 temperature: 23 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: Westerly
Average wind speed during the last 24 hours: 5-10 mph
Maximum wind gust in the last 24 hours: 15-20 mph
New snowfall in the last 24 hours: 5 inches
Total snow depth: 117 inches
weather

Precipitation will continue this morning, as an upper level trough of low-pressure affects the advisory area.  Snow levels will be near 4500ft.  The snowfall and rain will taper off by the early afternoon, as high-pressure begins to build.  Skies will steadily clear overnight and into tomorrow, allowing for a short break in the unsettled weather pattern.  The next storm is set to arrive on Wednesday, and will bring little precipitation and warm temperatures.  Sunny springtime weather is expected by the weekend.

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In Mt Shasta City at 0500, we have a current temperature of 32 F.

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

Sand Flat - 6,750 ft, the current temperture is 23 degrees F.  Temperatures have ranged from 23 F to 33 F.  Snow on the ground totals 117 inches with 5 inches of new snow and 1 inch of settlement.

Old Ski Bowl - 7,600ft. the current temperature is 21 degrees F.  Temperatures have ranged from 21 F to 31 F.  Snow on the ground totals 199 inches with 7 inches of new snow and little settlement. 

Gray Butte - 8,000 feet, the current temperature is 17 degrees F. Temperatures have ranged from 17 F to 28 F.  Winds have averaged 10-20 mph with gusts to 35 mph, blowing west/southwest and shifting northwest.

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

Castle Lake - 5,800 feet, the current temperature is 23 degrees F. Temperatures have ranged from 23 F to 36 F. Snow on the ground totals 104 inches with 4 inches of new snow and little settlement. 

Mt Eddy - 6,500 feet, the current temperature is 20 degrees F. Temperatures have ranged from 18 F to 34 F. Snow on the ground measures 104 inches with 4 inches of new snow and 1 inch of settlement. Winds have been southerly averaging 2-3 mph with gusts up to 13 mph.

THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 49.15 inches of water, normal is 34.79 inches, putting us at 141% of normal.  For the month of March, we have received 5.84 inches of water, normal is 5.29 inches, which is 110% of normal. And finally for the year of 2017, we received 27.99 inches of water, normal is 19.58 inches, putting us at 143% 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.

Two-Day Mountain Weather Forecast Produced in partnership with the Medford NWS
For 7000 ft. to 9000 ft.
  Monday Monday Night Tuesday
Weather: 90% chance of snow showers before 11am, then 30% chance snow of snow showers. Partly cloudy Mostly Sunny
Temperatures: 36 deg. F. 24 deg. F. 46 deg. F.
Wind direction: West North North
Wind speed: 9-16 mph 17 mph 14-16 mph
Expected snowfall: .5-1 in. 0 in. 0 in.
For 9000 ft. to 11000 ft.
  Monday Monday Night Tuesday
Weather: Windy. 90% chance of snow showers before 11am, then 30% chance snow showers. Wind chill values as low as -16. Partly cloudy and windy. Wind chill values as low as -4. Mostly sunny and windy.
Temperatures: 21 deg. F. 21 deg. F. 29 deg. F.
Wind direction: West/Northwest North/Northwest North/Northwest
Wind speed: 36-41 mph 60-70 mph 28-33 mph
Expected snowfall: 1-2 in. 0 in. 0-1 in.
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.
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