You are here

Avalanche Advisory for 2017-01-06 06:58:19

  • EXPIRED ON January 7, 2017 @ 6:58 am
    Published on January 6, 2017 @ 6:58 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

Today, MODERATE avalanche danger prevails for all aspects and elevations. The avalanche danger will gradually increase to CONSIDERABLE or HIGH danger tonight into tomorrow. A winter storm watch is in affect beginning this evening. Southwesterly winds will increase and abundant precipitation is in the forecast.  Persistent slab avalanches are unlikely today, but should be monitored as this wet winter storm will rapidly add weight to the snowpack. Human triggered wind slabs remain possible today.
 

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

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

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

Both old and new wind slabs still exist in the backcountry. Visible blowing over recent days forming new wind slabs as well as old wind slabs lurk near and above treeline. Human trigger of said slabs is possible. Look for clues such as drifting snow, cornices, and wind pillows to identify areas of recent wind loading and subsequent wind slab formation. Identify and avoid areas where wind slabs are likely to exist. This problem is most likely to be found near and above treeline on NW-N-NE-E-SE facing slopes but could be found in more isolated areas on other aspects or below treeline. Loaded slopes steeper than 37 degrees could produce small to large scale avalanches. Weak layers could include the old snow/new snow interface or anywhere within recent storm snow.

 

Avalanche Problem 2: Persistent Slab

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

While we have not seen any avalanches occur on the 12/23 or 1/1 persistent weak layers, snowpit tests have produced continued easy to moderate failures from both layers. Today, it's unlikely to trigger any persistent slab avalanches. However, a potent winter storm on tap for this weekend could bring several inches of water and/or feet of new snow. All this weight to the snowpack could ignite these weak layers and produce a large and destructive avalanche. Remember, these weak layers have been most notable on near treeline cold, shady aspects (NW-N-NE-E) throughout the advisory area. This layer exists as rounding facets and is now buried by 2-4 feet of new snow and even more after this weekends storm. As new snow continues to increase the load on the snowpack, large persistent slab trending to deep slab avalanches are an increasing concern. Any avalanches that either initially fail on or step down to this weak layer will be large and destructive. Recent snowpit data has shown variability on the degree of weakness in this layer from one location to another, but it is still a problem. 

Forecast Discussion

We've taken storm slabs off the list of avalanche problems today but wind slabs and our persistent slab problems remain. While the overall avalanche danger has been decreasing over the past few days, it is not impossible for one to trigger a lurking wind slab. Our persistent slab problem remains as a reminder that those weak layers still exist.  With this weekends incoming storm, those layers could be activated by heavy, wet snow adding too much weight for the snowpack to handle. We will quickly progress back into considerable to high avalanche danger this weekend. As always, know before you go! Check the avalanche forecast, know how to use your equipement, ski and ride one at a time in avalanche terrain, don't regroup in run out zones. 

Reminders! Avalanche Awareness, tonight at 7pm at the Shasta Mountain Guides storefront in Mt Shasta. Tomorrow, Companion Rescue clinic, meet at The Fifth Season at 9am. Details on our website. Also, the Backcountry Film Festival, a fundraiser for the Mt Shasta Nordic Center, is Saturday! Check their website for details. (www.mtshastanordic.org

=============================================================

LOCAL AREA ROAD, NORDIC, AND SNOWMOBILE PARK STATUS:

The Sand Flat cross country ski trails are in good shape and ready for your cross country skis and snow shoes.  These are backcountry routes marked with blue diamonds on trees.  Trails are not groomed.  Snow shoers, please blaze a parallel trail to cross country skiers staying out of the skin track.  These trails can be accessed via the Everett Memorial Highway.  Thank you, and enjoy!

The Mt. Shasta Nordic Center is OPEN for the season! Take advantage of this wonderful venue. Groomed trails accomodate both classic and skate skiing styles. Rentals available. Visit their website for more details.  http://www.mtshastanordic.org

The Pilgrim Creek & Deer Mountain Snowmobile Parks are open, however there is no snow at these locations currently. One must drive down the 19 road (Military Pass) for several miles to get to consistent snow before unloading. Private industry is logging out there so watch out for log trucks. Head to our "Education" tab on our website and find the snowmobile section for trail information, grooming status, and other sledder resources.

The Castle Lake Road is OPEN. The Everett Memorial Highway is OPEN. The Castle Lake and Everett Hwy are plowed year round to the trailheads. The roads are not always first priority, so your dawn patrol powder mission might be ceased if the plow has not made it up yet. Siskiyou County does a great job keeping the roads clear. Be respectful of the plow drivers if you encounter them. If you get to Bunny Flat before or during when the plow is there, please park on the uphill, LEFT side of the parking lot as you drive in. This is uphill and lookers right of the bathrooms. Thank You!

The Five Red Flags of Avalanche Danger any time of year include: 1) Recent/current avalanche activity 2) Whumphing sounds or shooting cracks 3) Recent/current heavy snowfall 4) Strong winds transporting snow 5) Rapid warming or rain on snow.

Recent Observations

Clear blue skies and a gorgeous day greeted backcountry enthusiasts yesterday. The parking lot at Bunny Flat was fairly devoid of users, but those that did venture out likely found some good riding conditions. Conditions above treeline are variable. Windy locales on the mountain are hosting firm, wind packed powder, sastrugi features and some firm, icy areas along ridgelines. Gullies and less windy areas, softer snow can be found. Near treeline, it's a bit of a blend of wind affected snow, wind slabs and softer powder snow. A thin sun crust was noted on sunny, southerly aspects below 8,000 feet two days ago and could still be found in select areas. Below treeline, soft powder snow should not be hard to find though debris falling from the giant Red Firs has compacted and hardened snow near the bases of the big firs. 

We have no new and notable snowpack or avalanche observations. Upwards of 6 inches of settlement has occured in the snowpack over the past several days. Winds have had their moments, mostly from the SW, W and NW with a few easterly bursts. Wind transport of snow has been visible on the upper mountain, however less so at mid-mountain levels. 

This morning, an inversion is in place with temps in Mt Shasta in the single digits and below zero in a few spots. In the mountains, temperatures are in the high teens to low twenties. 

 

 

 

Weather and Current Conditions

Weather Summary

A winter storm watch is in effect from this evening through Saturday evening. Very cold temperatures this morning, below zero in some places locally and record setting in Klamath Falls which sits at -19F. That is 10 degrees cooler than their record for today of -9 from 1977. In Agrimet Station in Lorella, OR, it is 27 degrees below zero!! Burr. 

From the looks of things this morning, get ready for a bit of a maelstrom over the weekend and into next week. From Friday night to Wednesday of next week, precipitation forecasts are calling for upwards of 6.75 inches of water for Mt Shasta. We are going to see this start out as snow, switch to rain and then hopefully back to snow by the end of the period. Indeed the temperatures are going to rise as a warm front enters the area today and tomorrow. Snow levels will reach 7 - 8,000 feet by Saturday evening. Flooding is a concern from massive amounts of run off due to rain on snow. Winds will howl on the mountain all weekend out of the southwest. So, while all the water is great for reservoirs, powder hounds will sag their heads thinking about rain on snow. 

===========================================================

In Mt Shasta City at 0500, we have a current temperature of 6 F with clear skies.

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

Old Ski Bowl - 7,600 feet, the current temperature is 21 degrees F.  Temperatures have ranged from 7 F to 23 F. Snow on the ground totals 87 inches with no new snow and 2 inches of settlement

Grey Butte - 8,000 feet, the current temperature is 24 degrees F. Temperatures have ranged from 9 F to 24 F.  Winds have averaged 10 mph with gusts to 28 mph, easterly in nature.

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

Castle Lake - 5,600 feet, the current temperature is 14 degrees F. Temperatures have ranged from 6 F to 15 F. Snow on the ground totals 46 inches with no new snow and 1 inch of settlement.

Mt Eddy - 6,500 feet, the current temperature is 17 degrees F. Temperatures have ranged from 9 F to 19 F. Snow on the ground measures 48 inches with no new snow and 3 inches of settlement.  Winds have averaged 2-4 mph with gusts to 11 mph, blowing southwest in direction.

THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 22.56 inches of water, normal is 16.38 inches, putting us at 137% of normal.  For the month of January and for the year of 2017, we received 1.40 inches of water, normal is 1.17 inches, putting us at 119% 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: 8
Max. temperature in the last 24 hours: 20
Average wind direction during the last 24 hours: Easterly
Average wind speed during the last 24 hours: 5-10 mi/hr
Maximum wind gust in the last 24 hours: 25 mi/hr
New snowfall in the last 24 hours: 0 inches
Total snow depth: 53 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 Clear this morning with Increasing clouds Snow, mainly after 10pm. The snow could be heavy at times. Breezy, Chance of precipitation is 80%. Snow. The snow could be heavy at times. Windy. Chance of precipitation is 100%.
Temperature (°F) 23 25 33
Wind (mi/hr) East, becoming south/southeast 5-10 mph South 10-15 mph South 15-20 mph
Precipitation SWE / Snowfall (in) / 0 / 3-5 / 9-13
For 9000 ft to 11000 ft
  Friday Friday Night Saturday
Weather Increasing clouds. Wind chill values as low as -1. Breezy, A 50 percent chance of snow, mainly after 10pm. Mostly cloudy. Wind chill values as low as -4. Windy. Snow. The snow could be heavy at times. Wind chill values as low as -6. Windy. Chance of precipitation is 100%.
Temperature (°F) 19 19 22
Wind (mi/hr) West/Southwest 5-15 mph South/Southwest 0 Southwest 40-50 mph
Precipitation SWE / Snowfall (in) / 0 / 3-7 / 12-18

Disclaimer

This advisory does not apply to Ski Areas or Highways and is for the Mt. Shasta, Castle Lake and Mt. Eddy back country. Use this information for guidance only. You may find different conditions in the back country and should travel accordingly. This advisory expires on midnight of the date it was posted unless otherwise noted.