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Avalanche Advisory for 2015-03-27 07:01:02

  • EXPIRED ON March 28, 2015 @ 7:01 am
    Published on March 27, 2015 @ 7:01 am
  • Issued by Jon Dove - Shasta-Trinity National Forest

The avalanche danger is currently LOW for all elevations and aspects.  Loose wet snow instabilities, roller balls, and pin wheels are possible on S-SE-E aspects, especially in the afternoon.  Slides large enough to bury a person are unlikely, however, they can knock one off their feet and push them into undesirable terrain.  Normal caution is advised.

Carry a beacon shovel and probe. Wear a helmet. Know how to use your ice axe and crampons.

 

 

 

 

 

 

 

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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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Loose wet snow instabilities, roller balls, and pin wheels are possible on S-SE-E aspects, especially during the warmest parts of the day.  Slides large enough to bury a person are unlikely, however, they can knock one off their feet and push them into undesirable terrain.  Normal caution is advised.

Recent Observations

A set of two brief storms earlier in the week on Monday and Tuesday brought a fresh coating of snow to Mount Shasta.  Up to 9+ inches fell then was transported by moderate to strong SW-W-NW winds scouring ridge tops and roll overs, and depositing on S-SE-E-NE aspects.  The storms were followed on Wednesday and Thursday by steadily increasing temperatures and sunny skies.  A record high temperature of 77 F was set in Mt. Shasta City on Thursday, breaking the old record by 4 degrees!  Today is forecast to be warm as well, but a few degrees cooler than yesterday.  Clouds will begin to build during the day with a slight chance of precipitation and possibly even thunderstorms this evening.  Winds will be out of the SW increasing as a cold front approaches then calming later tonight.  Winds are forecast to be breezy at the upper elevations of the mountain (above 9,500 feet) with speeds of 30-40 mph with higher gusts.

Observations reported from the mountain yesterday revealed some loose wet snow slide activity occurring on the SSE aspect of Casval Ridge that drops into Avalanche Gulch.  Starting zones for these slides was about 10,000-10,200 feet (photo below).  There will be the right conditions for similar instabilities today, especially in the warm afternoon hours.  Be cautious skiing or traversing along S-SE-E slopes later in the day.  These types of slides are typically not dangerous themselves, but they could knock one off their feet and push them into undesirable terrain.  Where snow had been scoured by winds down to the old snow surface, corn snow could be found.  Where the new snow has been deposited it has yet to fully transition via melt/freeze cycle into corn snow conditions.  An individual who skied Powder Bowl yesterday reported that the top half of the bowl that had been wind scoured was good corn snow. Half way down the slope the snow then transitioned into "manky"  and thick conditions.  No loose wet snow instabilities were reported in Powder Bowl/Sun Bowl area.   

Photos:
Top-Group break on ski descent along edge of Avalanche Gulch proper (3/23/2015) - Photo: Jon Dove

Bottom-Loose wet snow slides off the SSE aspect of Casaval ridge. Photo taken from 50/50 flat (3/26/2015) - Photo: Tim Dobbins

Continue to always use safe travel methods: carry situational awareness on your skin up the mountain, choose safe routes and watch for what others are doing, ski one at a time, stop in safe zones!

For folks that plan on climbing Mt. Shasta:  Route conditions on Casaval Ridge, Sargents Ridge, and Avalanche Gulch are currently good.  That being said, the snow conditions will be variable as one will encounter areas that have been scoured down to the old snow surface and areas where snow from Monday and Tuesday has been deposited.  The areas of newer snow coverage have yet to fully make the transitions into corn snow.   Ice fall from rime ice that has built up on the Red Banks and other rock outcroppings will be happening even in the early morning hours.  A helmet, crampons, and a mountain axe are necessary equipment and should be used. 

Castle Lake and Mt Eddy zones are still hosting a shallow snowpack. All areas below about 6,000 feet in the forecast area are hosting patchy snow with dirt showing around trees and in sunny spots.  For Castle Lake, skiing is out of the question at this point due to lack of snow.

Report your observations to the MSAC! A photo, a few words... send them in! (nimeyers@fs.fed.us or 530-926-9614)

Sand Flat Winter Trails: OPEN, however snow depths are meager and the Lower Sand Flat road is exposed dirt. We recommend heading up to Bunny Flat and touring up the road or anywhere higher in elevation!

Pilgrim Creek Snowmobile Park: CLOSED due to lack of snow

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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’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.

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

 


 

    Weather and Current Conditions

    Weather Summary

    In Mt Shasta City this morning at 0500, we have clear skies and a current temperature of 41 F degrees. 

    WEATHER STATION INFORMATION (0500hrs):

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

    Old Ski Bowl - 7,600 feet, the current temperature is 42 F. Snow on the ground totals 83 inches with 5 inches of settlement since Monday.  Temperatures have ranged from 40 F to 58 F.

    Gray Butte - 8,000 feet, the current temperature is 43 F. Temps have ranged from 42 F to 55 F. Winds have been variable blowing primarily southwest in the last 12 hours averaging 5 mph with max gusts to 28 mph, East.

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

    Castle Lake - 5,600 feet, the current temperature is 46 F. Temps have ranged from 34 F to 54 F. The Castle Lake area has very little snow left on the ground.

    Mt Eddy - 6,500 feet, the current temperature is 35 F. Temps have ranged from 45 F to 66 F in the last 24 hours. Current snow depth is 18 inches with 2 inches settlement since Monday.  Winds have been averaging 3 mph, with gusts to 9 mph, ENE.

    WEATHER SYNOPSIS: The week started off with some stormy weather on Monday and Tuesday that brought a fresh coating of snow for Mt. Shasta.  Storm clouds parted and gave way to sunny and warm temperatures on Wednesday and Thursday. A record high temperature was set in Mt. Shasta City on Thursday at 77 degrees, breaking the old record by 4 degrees!  Temperatures will be slightly cooler today as a cold front approaches this afternoon into this evening.  This cold front will bring a slight chance of precipitation.  Water totals, however, will be almost negligible (0.01 inches).  There will also be a slight chance of thunder storms, as well.  Winds will increase through the day becoming breezy at the upper elevations (above 9,500 feet) then calming in the evening.  They will be coming out of the SW, then shifting to the NW tonight.  Skies will clear on Saturday as the cold front moves east.

    THIS SEASON PRECIPITATION: Since October 1st (the wet season) , we have received 31.43 inches of water, normal is 34.79 inches, putting us at 90% of normal. For the month of March, we sit at 1.27 inches of water, normal is 5.29, putting us at 24% of normal. For the year of 2015, we've received 11.91 inches water, normal is 19.58, equalling 60% of normal. 

     
    Snow Survey Results for March 2015 for the Sacramento, Shasta and Trinity Watersheds: 49% of normal with at average depth of 37 inches. Historic average for snow is 76.8 inches. Last year at this time we were 36% of normal. Similar years to this year are 1936, 1977, 1988, 1994.

    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: 42
    Max. temperature in the last 24 hours: 58
    Average wind direction during the last 24 hours: Variable
    Average wind speed during the last 24 hours: 4 mph mi/hr
    Maximum wind gust in the last 24 hours: 28 mi/hr
    New snowfall in the last 24 hours: 0 inches
    Total snow depth: 83 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 Sunny with increasing clouds in the afternoon Mostly cloudy with a 30% chance of rain, slight chance of thunder storms Partly Cloudy
    Temperature (°F) 60 34 53
    Wind (mi/hr) South 10-20 mph with gusts to 30 mph Southwest shifting to Northwest after midnight 10-15 mph North 10-15 mph
    Precipitation SWE / Snowfall (in) / 0 / 0 / 0
    For 9000 ft to 11000 ft
      Friday Friday Night Saturday
    Weather Sunny with increasing clouds in the afternoon Mostly Cloudy with 40% chance snow Partly Cloudy
    Temperature (°F) 40 27 42
    Wind (mi/hr) South-Southwest 15-25 mph increasing to 30-35 mph with higher gusts Southwest 0 Northwest 15-25 mph with higher gusts
    Precipitation SWE / Snowfall (in) / 0 / Less than 1/2 inch / 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.