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Avalanche Advisory for 2017-01-20 06:32:28

  • EXPIRED ON January 21, 2017 @ 6:32 am
    Published on January 20, 2017 @ 6:32 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

...A winter storm warning is in effect until 4pm PST this afternoon... winter storm watch is in effect from Saturday afternoon through Sunday afternoon...

Today and the weekend, another series of winter storms will add an additional 1 to 2 feet of snow on top of already several feet of new snow from the past two days. Wind slabs near and above treeline remain the primary concern. CONSIDERABLE to HIGH avalanche danger will continue for slopes steeper than 30 degrees. 

 

 

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Avalanche Problem 1: Wind Slab

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New snow and wind loading continue near and above treeline. Wind slabs have the potential to be large.  Stay off slopes steeper than 30 degrees and out from beneath avalanche paths. Look for blowing snow, cornice formation, wind pillows, and snow surface clues as to where wind slabs exist.  Avoid recently wind loaded terrain.

 

Avalanche Problem 2: Storm Slab

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Storm slabs remain possible today. An additional 6-8 inches of new snow fell overnight. Areas near treeline and below treeline will host the best storm slab potential. Signs of storm snow instabilities could be snow surface cracking, snow collapsing, and whumpfing.  Avoid slopes steeper than 30 degrees in areas where signs of unstable storm slabs are present.

Avalanche Problem 3: Cornice

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Ridgelines within the forecast area still hold small to large cornice features, particularly on the west side in the Castle Lake and Cliff Lake areas. Rapid accumulation of new storm snow will add weight to remaining cornices. Either new cornices could be easily triggered and/or new snow will add weight to old cornices and cause the whole feature to break off. 

Forecast Discussion

We are right back at it here in good ol' Mt Shasta. The piles of snow are growing and we love it! Heavy snow falls currently this morning and will continue to do so. The Everitt Memorial Highway road status is unknown at this time. As of yesterday afternoon, we heard that plows were working on the road, but with heavy snow and wind again this morning, that could compromise things. Winter will delivery another kick in the keister this weekend with several feet of new snow along with hurricane force winds on Sunday. The NWS has issued a winter storm warning in effect until 4pm today and also a winter storm watch in effect from Saturday afternoon through Sunday afternoon. The avalanche danger will remain elevated with wind slabs leading the avalanche problem charge, and storm slabs/cornices close behind. If you can make it into the backcountry, things could be a little dicey. Batten the hatches, hang on to your hats and tighten your boots because it's on!  

 

 

Recent Observations

Temperatures are 1 to 2 degrees cooler this morning with heavy snow falling. Windy conditions have kicked up in town and in the hills, blowing west/southwest/south. Yesterday, observations were made on Gray Butte via the Ski Park and also the Old Ski Bowl area via snowmobile and Old McCloud road. While we thought we fixed the weather station, it is still down. We'll keep working on this issue and thanks for being patient. Don't forget about the Sand Flat site, as it has snow depth also. Very deep snow was encountered yesterday. Whatever was your choice of recreation, it was not for the faint of heart. Visibility was difficult. However, for a very brief moment from about 8,000 feet, we were able to catch a glimpse at the upper mountain. Surprisingly, we did not see any obvious signs of recent avalanches but our window was short and narrow. What looked like a small crown on the east aspect of Green Butte was observed, but not notable. Overall, the snow appeared mostly smooth with isolated scalloped areas. Snow conditions near treeline were superb with light density snow to your hearts delight. Heavier, wet snow began at about 5,500 to 6,000 feet upon descending. Above 8,000 feet, wind slabs began to show. Snowpit tests have indicated a right side up snowpack structure and good stability. This again is a little surprising... but also we have not been able to, nor would really feel it's safe, to make our way onto steeper terrain where it could be a totally different ballgame. At this point, we are receiving a lot more snow and wind, continuing to load leeward slopes. While yesterday it seemed like only steeper (>37 degrees), unsupported, wind loaded slopes above treeline were the major concern, with the new additional weight of the current storm snow, lower angle slopes will continue to be a concern (>30 degrees). It has been difficult to get around to many areas due to deep snow and poor visibility. We want to stress that just because we are not seeing a lot of obvious clues for instability... this does not give the green light to shred. Things could be much different elsewhere so pay attention out there!

 

Weather and Current Conditions

Weather Summary

We are in it now. Heavy snow impacts the forecast area again this morning. Already we have several inches on the ground and upwards of 6+ inches on the mountain. Expect a good dose of snow for the weekend. Precipitation will continue through today, a very brief high pressure area will give us a short break on Saturday and then another extremely windy system will replace it on Sunday. Snow levels will be around 3,000 to 3,500 feet for the duration of the weekend. Precip totals are predicted to be near 2 inches of snow/water equivalent by Sunday morning... and then some more with very strong wind. More on that later. The bottom line, winter has it's grip on Mt Shasta this weekend. Be safe out there!

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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...

Old Ski Bowl - (7,600ft) Not recording data at this time.  We are working to get this station up and running again ASAP. Sand Flat (6,750 feet) is recording 6 new inches of snow in the last 24 hours with a total of 86 inches.

Grey Butte - 8,000 feet, the current temperature is 18 degrees F. Temperatures have ranged from 18 F to 24 F.  Winds have averaged 10-15 mph with gusts to 28 mph, blowing out of the west/southwest.

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

Castle Lake - 5,600 feet, the current temperature is 24 degrees F. Temperatures have ranged from 24 F to 30 F. Snow on the ground totals 70 inches with about 5-7 inches new snow and little settlement.

Mt Eddy - 6,500 feet, the current temperature is 22 degrees F. Temperatures have ranged from 21 F to 27 F. Snow on the ground measures 76 inches with 2-4 inches new snow and little settlement.  Winds have averaged 2-4 mph with gusts to 23 mph, blowing southeast to southwest.

THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 29.95 inches of water, normal is 19.69 inches, putting us at 152% of normal.  For the month of January and for the year of 2017, we received 8.79 inches of water, normal is 4.48 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: 23
Max. temperature in the last 24 hours: 29
Average wind direction during the last 24 hours: West/Southwest
Average wind speed during the last 24 hours: 10-15 mi/hr
Maximum wind gust in the last 24 hours: 28 mi/hr
New snowfall in the last 24 hours: 6+ inches
Total snow depth: 86 inches

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Friday
(4 a.m. to 10 p.m.)
Friday Night
(10 p.m. to 4 a.m.)
Saturday
(4 a.m. to 10 p.m.)
Weather Snow before 10am, then snow showers after 10am. The snow could be heavy at times. Breezy. Chance of precipitation is 100%. Snow showers. Chance of precipitation is 100%. Snow showers before 4pm, then snow after 4pm. Chance of precipitation is 100%.
Temperature (°F) 27 22 27
Wind (mi/hr) South 15-25 mph South 10-20 mph South 15-25 mph
Precipitation SWE / Snowfall (in) / 5-10 / 4-8 / 3-6
For 9000 ft to 11000 ft
  Friday Friday Night Saturday
Weather Snow before 10am, then snow showers after 10am. The snow could be heavy at times. Wind chill values as low as -17. Windy. Chance of precipitation is 100%. Snow showers. Wind chill values as low as -17. Windy. Chance of precipitation is 100%. Snow showers before 4pm, then snow after 4pm. Wind chill values as low as -17. Windy. Chance of precipitation is 100%.
Temperature (°F) 13 9 13
Wind (mi/hr) Southwest 25-35 mph, decreasing in afternoon Southwest 8-12 West/Southwest 40-50 mph
Precipitation SWE / Snowfall (in) / 8-12 / 5-9 / 3-7

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.