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Avalanche Advisory for 2014-04-06 06:39:28

  • EXPIRED ON April 7, 2014 @ 6:39 am
    Published on April 6, 2014 @ 6:39 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

MODERATE avalanche danger may form on sun exposed E-SE-S-SW-W aspects during the warmest portions of the day, especially above treeline. Loose wet snow avalanches will be possible on slopes steeper than 35 degrees. Larger slab avalanches remain unlikely, however small to medium wind slab avalanches triggered by a skier/climber will be possible today.
Overall, LOW avalanche danger exists for all other areas.

Carry a beacon, shovel and probe and know how to use them!

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

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: Loose Wet

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Spring sun with warm daytime highs will allow for loose wet snow instabilities like roller balls, pinwheels, and loose wet snow sluffs to occur today. While most of these loose wet avalanches should remain too small to bury a person, they could still push a person into an area with undesireable consequences or where terrain traps exist. Larger slab avalanches remain unlikely today; however, they are not impossible, especially on wind loaded aspects.


 

Avalanche Problem 2: Wind Slab

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Wind out of the northwest caused some new wind loading and formed small new wind slabs up to 2-4 inches thick by the afternoon yesterday. These very small wind slabs did not grow large enough to cause problems for backcountry travelers. Continued northwesterlies today could increase the size of the newly formed wind slabs.Use caution on leeward aspects, NE - E - SE - S. Wind slabs will be most sensitive to trigger during the next 24-48 hours.

Recent Observations

Yesterdays observations on Gray Butte, Green Butte and in various areas of the Old Ski Bowl indicated that the snowpack continues to settle and consolidate. Formal snowpit tests did not reveal any signs of instability associated with the recent storm snow or wind slabs. Snowpit data in said areas indicated that the near crust facets (weak snow under an old crust) continues to gain strength.

Of biggest concern for today will be wet-loose avalanches within the top 4-6 inches or more of new snow on top of our widespread crust layer. Sunny slopes E - SE and S facing saw widespread roller ball and pin wheel action yesterday as temperatures warmed into the afternoon. Small to medium size wet loose slides were easily triggered within the top layer of snow. While we will get some refreeze, we will likely see more of that today. These wet loose slides generally start small and entrain more snow as they slide down the hill. Slopes steeper than 35 degrees and E - SE and S facing will see most of this action today. With the warming trend occuring, I expect a general decline in the avalanche danger and a move toward more spring corn by mid week!

Wind out of the northwest did cause some new wind loading and formed small new wind slabs up to 2-4 inches thick by the afternoon. These very small wind slabs did not grow large enough to cause problems for backcountry travelers. Continued northwesterlies today could increase the size of the newly formed wind slabs. I don't expect said slabs to gain enough size to pose a real threat, but use caution regardless on leeward aspects, NE - E - SE - S. Wind slabs will be most sensitive to trigger during the next 24-48 hours.

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For climbers, conditions have been excellent on all routes. With the recent new snow however, be sure to thoroughly read this avalanche advisory. Over snow travel with the new snow will be difficult (i.e. post-holing) without snowshoes/skis/splitboard at this time. The season for climbing Mt Shasta is going to be shifted forward this year. On a normal year with ample snow on the ground, good climing conditions usually start in April and can go all the way into July sometimes. This year is not the case...the best conditions to climb Shasta this year will be NOW through April and potentially May. The extent of good climbing conditions will hinge on our Spring weather. More snow could potentially extend the season and warm days with shining sun will shorten it. While the mountain looks like it's got a thick blanket of snow on it, in reality there is only about 2-5 feet of snow on the ground, depending on aspect and elevation. Good climbing conditions, in general, means snow on the mountain. As the snow melts, rockfall increases and a climb of Shasta becomes more dangerous. All in all, sooner than later will be best for climbing Shasta. Check the climbing advisory on our webpage also!

PLEASE NOTE: Snow conditions on most routes are smooth and firm, especially in the AM hours. Conditions as such have lead to accidents due to slip/falls and failure to self arrest. A slip and fall on smooth, firm and sometimes icy snow can result in a slide for life on the steeper slopes of Mt Shasta. Self arrest skills with an ice axe and proper crampon use are essential for a safe climb. Do not under estimate the importance of proper knowledge and skills with your ice axe/crampons/self arrest techniques. Further, an avalanche beacon, shovel and probe are recommended for any climbers attempting Shasta currently. Lastly, with snow on  mountain, the rockfall danger has been low. However, rime ice can plaster exposed rocks on Shasta this time of year. As the days warm, the rime ice will flake off and fall onto climbers below, especially on the Avalanche Gulch route. Ice is like a rock and a HELMET should always be worn.

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While Northgate, Brewer Ck and Clear Ck trailheads are officially closed, the bathrooms are still open with packout bags inside, and one can still access the Mt Shasta Wilderness. However, your summit pass and wilderness permits must be purchased at McCloud or Mt Shasta Ranger Stations. NO DOGS are allowed in the Mt Shasta Wilderness OR Sierra Club Property. Thanks!

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Terrain:  Remember most of the terrain that we like to play on is greater than 30 degrees.  Avalanches are possible on anything steeper than 30 degrees.  Avoid cornices, rock bands, terrain traps and runout zones of avalanche paths.

Weather:  Most of our areas avalanche danger will occur 24-48 hours after a storm. We still can see persistent weak layers from time to time and we always will be sure to let you know about that!  Heed the basic signs: Wind (significant snow transport and depositions), Temperature (rain/snow/rain/snow, which in turn weakens the snowpack), and Precipitation (Snow or rain add weight and stress to the current snowpack).

SnowpackIf snow accumulates, give the snowpack a chance to adjust to the new snow load before you play on or near steep slopes (greater than 30 degrees).  Most direct action avalanches occur within 24-48 hours of recent snowfall.  Watch for obvious signs of snowpack instability such as recent natural avalanche activity, collapsing of the snowpack (often associated with a “whumphing” sound), and shooting cracks. If you see these signs of instability, limit your recreation to lower angle slopes.

Human Factor: Don’t forget to carry and know how to use avalanche rescue gear. You should NOT be skiing or climbing potential avalanche slopes without having beacons, shovels, and probes.  Only one person in a group should be exposed to potential avalanche danger at a time.  Remember, climbing, skiing, and riding down the edge of slopes is safer than being in the center.  Just because another person is on a slope doesn’t mean that it is safe.  Be an individual!  Make your own decisions.  Heed the signs of instability: rapid warming, “whumphing” noises, shooting cracks, snowing an inch an hour or more, rain, roller balls, wind loading, recent avalanche activity.

 


 

    Weather and Current Conditions

    Weather Summary

    In Mt Shasta City this morning at 0500, we have clear skies with a current temperature of 48F.

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

    Old Ski Bowl - 7,600 feet. The Old Ski Bowl weather station has no new snow in the last 24 hours. The current temperature is 34F with a low of 21F and a high of 38F. Total snow depth is 74 inches with 3 inches settlement.

    Gray Butte - 8,000 feet - The current temperature is 31F. Temps have ranged from a low of 22F to a high 36F.  Winds have been calm, 4 mph and variable in direction up until 2000. Since then, the northwesterlies have turned on and have averaged 15-20 with max gusts topping out at 35 mph from the NW also.

    Castle Lake and Mt Eddy (West side of I-5)... 

    Castle Lake - 5,600 feet, the current temperature is 36F with a low of 28F and a high of 44F. Castle Lake has received no new snow and hosts a current snowpack of 7 inches with 2 inches settlement at the weather station.

    Mt Eddy - 6,500 feet, the current temperature is 35F with a low of 27F and a high of 40F. Mt Eddy has received no new snow and the current snow depth total is 29 inches. Winds have averaged 2-3 mph, with gusts to 14 mph, out of the southeast.

    THIS SEASON: Since September 1st , we have received 13.77 inches of water, normal is 36.71 inches, putting us at 37% of normal. For the year of 2014, Mt Shasta has received 10.95 inches of water with normal being 20.83 inches which puts us at 52% of normal. And lastly, for April we sit at 93% of normal, receiving .54 inches of water, normal is .58 inches. Mt Shasta finished off March at 73% of normal, accumulating 4.37 inches of water with normal being 5.96 inches.

    WEATHER SYNOPSIS:

    Temperatures and northwest winds will increase today. With the jet stream overhead, northwest winds have kicked in since 2000 last night and will peak in the AM hours before dying off later tonight as the jet shifts eastward. A warm bubble pushes its way into our area this morning and by Monday, we will see drastically warmer daytime highs in the mid 60s for town. So, as mentioned before, warming and drying continues and we should get that in full effect by this afteroon. The work week looks to be mostly clear and sunny with southwest flow and calm winds. Temps will cool a bit as the week progresses.

    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. It is not uncommon for late season storm to arrive and create winter conditions on Shasta.  Be prepared.

    CURRENT CONDITIONS at Bunny Flat (6950 ft)
    0600 temperature: 34
    Max. temperature in the last 24 hours: 38
    Average wind direction during the last 24 hours: Variable, NW @ 2000 to present
    Average wind speed during the last 24 hours: 10-20 mi/hr
    Maximum wind gust in the last 24 hours: 35 mi/hr
    New snowfall in the last 24 hours: 0 inches
    Total snow depth: 74 inches

    Two Day Mountain Weather Forecast

    Produced in partnership with the Medford NWS

    For 7000 ft to 9000 ft
      Sunday
    (4 a.m. to 10 p.m.)
    Sunday Night
    (10 p.m. to 4 a.m.)
    Monday
    (4 a.m. to 10 p.m.)
    Weather Scattered clouds in AM, clearing and becoming sunny Mostly clear Sunny
    Temperature (°F) 55 34 62
    Wind (mi/hr) Northwest 5-15 mph Northwest 5-10 mph East, becoming south in PM 5-10 mph
    Precipitation SWE / Snowfall (in) / 0 / 0 / 0
    For 9000 ft to 11000 ft
      Sunday Sunday Night Monday
    Weather Scattered clouds in AM, clearing and becoming sunny Mostly clear Sunny
    Temperature (°F) 35 25 42
    Wind (mi/hr) Northwest 30-40 mph with gusts higher North 0 Southwest 10-20 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 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.