THIS AVALANCHE ADVISORY EXPIRED ON April 11, 2017 @ 6:51 am
Avalanche Advisory published on April 10, 2017 @ 6:51 am
Issued by Andrew Kiefer - Mt Shasta Avalanche Center
bottom line

The avalanche danger is MODERATE near and above treeline. Human triggered wind slab avalanches are possible. New snow and southwesterly winds continue to form shallow wind slabs on NW-N-NE-E-SE aspects near and above treeline. Natural avalanches are unlikely. LOW avalanche danger exists 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 and above treeline. Human triggered wind slab avalanches are possible. New snow and southwesterly winds continue to form shallow wind slabs on NW-N-NE-E-SE aspects near and above treeline. Natural avalanches are unlikely. LOW avalanche danger exists 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

Human triggered wind slab avalanches remain possible on W-NW-N-NE-E-SE aspects near and above treeline. Natural wind slab avalanches are unlikely today, and any wind slab avalanche would likely be small. Snow is still available for transport, and westerly and southerly winds are creating shallow, fresh wind slabs. Wind slabs will most likely be triggered on leeward slopes 35 degrees and steeper that are unsupported, have a convex shape, or that are just below ridgelines.     

advisory discussion

Overall, snowpack stability is good throughout the advisory area. Isolated pockets of fresh wind slab do continue to pose a hazard for backcountry travelers. Be sure to identify features of concern, and avoid steep wind loaded slopes, especially those with high consequence run-outs. Another significant winter storm is set for later in the week. Southerly winds will be steadily ramping up tomorrow, and heavy precipitation is expected by Wednesday night.

We will issue our last avalanche advisory of the season this Sunday, April 16th.

recent observations

The advisory area picked up 2-3 inches of snow over the past 24 hours and temperatures remained below freezing 6000ft and above. Skies were mostly cloudy throughout the day yesterday, with brief periods of sunshine. Winds have been blowing out of the west and south over the past several days. Wind speeds yesterday were light to moderate.

The recent storm snow settled several inches over the weekend, and overall, stability is improving. Snow is available for transport, and any snowpack instability is associated with fresh wind-loaded snow. The only avalanche observed or reported in the past several days occurred naturally on the northwest side of Green Butte Ridge on Friday. Southerly winds loaded this slope, which extends down into Avalanche Gulch. The avalanche had impressive propagation, but only ran a short distance and had a maximum crown height of 1ft.  

CURRENT CONDITIONS Weather observations from Bunny Flat
0600 temperature: 27 deg. F.
Max. temperature in the last 24 hours: 33 deg. F.
Average wind direction during the last 24 hours: west
Average wind speed during the last 24 hours: 10-15 mph
Maximum wind gust in the last 24 hours: 20 mph
New snowfall in the last 24 hours: 2 inches
Total snow depth: 122 inches
weather

Today will bring mostly cloudy skies with scattered snow showers in the morning. Little to no snow accumulation is expected. Conditions look to dry out by the afternoon, and the cloud cover will gradually break down throughout the day. High temperatures at the 6000ft level will reach the upper 30’s F. The dry and clear weather window will be short lived, as a strong low-pressure system will move into the area by tomorrow afternoon. This system looks to bring plenty of precipitation as well as gusty southerly winds. Winter will continue throughout the week with significant snowfall on Wednesday night and Thursday.

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In Mt Shasta City at 0500, we have a current temperature of 36 F

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

Sand Flat - 6,750 ft. The current temperature is 27 degrees F. Temperatures have ranged from 27 F to 33 F. Snow on the ground totals 122 inches with 2 inches of new snow, and 1 inch of settlement.

Old Ski Bowl - 7,600ft. The current temperature is 23 degrees F. Temperatures have ranged from 13 F to 32 F. Snow on the ground totals 207 inches with 3 inches of new snow and 2 inches of settlement.

Grey Butte - 8,000 feet. The current temperature is 22 degrees F. Temperatures have ranged from 15 F to 28 F. Winds have averaged 10-20 mph with gusts to 28 mph, blowing primarily from the west/southwest.

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

Castle Lake - 5,800 feet. The current temperature is 28 degrees F. Temperatures have ranged from 22 F to 39 F. Snow on the ground totals 111 inches with 2 inches of new snow and 2 inches of settlement.

Mt Eddy - 6,500 feet, the current temperature 24 degrees F. Temperatures have ranged from 15 F to 30 F. Snow on the ground measures 105 inches with 2 inches of new snow and 1 inch of settlement. Winds have averaged 1-3 mph with gusts to 21 mph blowing out of the south/southeast.

THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 53.42 inches of water, normal is 36.47 inches, putting us at 146% of normal. For the month of April, we have received 3.96 inches of water, normal is 1.01 inches, which is 392% of normal. And finally for the year of 2017, we received 32.26 inches of water, normal is 21.26 inches, putting us at 152% 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: Scattered snow showers mainly before 11am. Mostly sunny. Chance of precipitation 30%. Mostly Cloudy An 80% chance of snow showers.
Temperatures: 35 deg. F. 25 deg. F. 37 deg. F.
Wind direction: south south/southwest south
Wind speed: 12-17 mph 5-9 mph 13-21 mph
Expected snowfall: 0-.5 in. 0 in. 2-4 in.
For 9000 ft. to 11000 ft.
  Monday Monday Night Tuesday
Weather: Scattered snow showers, mainly before 11am. Windy. Wind chill values as low as -14 F. Becoming mostly sunny in the afternoon. Mostly cloudy and windy Snow likely and windy. Chance of precipitation is 70%.
Temperatures: 16 deg. F. 16 deg. F. 21 deg. F.
Wind direction: west/southwest south/southwest south/southwest
Wind speed: 36-41 mph 26-33 mph, gusting to 50 mph 40-50 mph, gusting to 80 mph
Expected snowfall: 0-.5 in. 0 in. 3-5 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.