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Avalanche Advisory for 2016-02-08 05:59:15
- EXPIRED ON February 9, 2016 @ 5:59 amPublished on February 8, 2016 @ 5:59 am
- Issued by Jon Dove - Shasta-Trinity National Forest
Bottom Line
Overall, LOW avalanche danger exists at all elevations, all aspects. Isolated wind slabs may still exist on protected terrain features. Around rock outcroppings, near ridge tops,on slopes 37 degrees and steeper will be area most susceptible to trigger. Loose wet snow instabilities will become an increasing risk on sun exposed aspects.
Normal caution is advised.
Avalanche Problem 1: Wind Slab
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Character ?
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Aspect/Elevation ?
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Likelihood ?CertainVery LikelyLikelyPossible
Unlikely -
Size ?HistoricVery LargeLargeSmall
Remaining wind slabs of small to possibly medium in size will be found on leeward S-SE-E-NE-N-NW aspects above treeline. If just the right trigger point is stumbled upon, the resulting slide could entrain enough snow to easily bury a person. Slopes 37 degrees and steeper, in complex terrain, steep chutes, convexities/roll overs, protected areas around rock outcroppings, just below ridge tops and cross loaded depressions will be the best places to encounter said wind slabs. Wind slabs will be stubborn, but not impossible to trigger. Colder, northerly aspects will host the highest sensitivity to triggering. Warmer, sunny aspects, one will find better bonded wind slabs.
Avalanche Problem 2: Loose Wet
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Character ?
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Aspect/Elevation ?
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Likelihood ?CertainVery LikelyLikelyPossible
Unlikely
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Size ?HistoricVery LargeLargeSmall
Sunshine and warming temperatures will increase the risk of loose wet snow instabilities over the next few days. Roller balls, pin wheels, and point release snow instabilities are possible. They will be found primarily on, but not limited to, southerly facing aspects below, near, and above treeline. While typically not a immediate danger to life, these types of slides could easily knock a person off of their feet and push them into a terrain trap, over a cliff band, or into other undesirable terrain. They could even entrain enough snow to bury a person. Loose wet snow slides will become more common in the coming days. Slopes that have a long, consistent fetch can produce large loose wet avalanches on Mt Shasta. These are more common in the Spring time, but still something to think about.
Forecast Discussion
The slow moving ridge of high pressure is currently centered over the region. Dry conditions and above normal temperatures will persist into Tuesday, then a gradual cooling trend will begin. A temperature inversion remains present with warm air aloft causing some low lying clouds. Any clouds, however, will quickly burn off as the day warms up. Scattered clouds will begin to appear on Wednesday as an "upstream" trough begins to approach the coast. Clouds will increase on Thursday, but there is no chance of precipitation for our area until Friday. Winds have steadily increased over the past 24 hours, but are forecast to remain moderate with wind speeds around 20 mph at mid-mountain elevations (10,000 ft) coming out of a Southerly direction.
THIS SEASON PRECIPITATION for MT SHASTA CITY: Since October 1st (the wet season), we have received 22.62 inches of water, normal is 23.73 inches, putting us at 95% of normal. For the month of February we've received 0.13 inches of water, normal is 1.46 inches, putting us at 8% of normal, and finally... for the year of 2016 we've received 13.13 inches of water, normal is 8.52 inches, putting us at 154% of normal .
Recent Observations
Observations yesterday revealed a snowpack that is still in transition. Snow surface conditions remained variable, but sunny skies and increasing temperatures are working the melt/freeze magic that will lead to corn snow formation. The only sign of instability was a few roller balls on southerly facing aspects near and below treeline. Reports from a group on Casaval ridge who had dug two snow stability pits to perform extended column tests had results of ECTN 17 and ECTN 21 in areas of wind slab development. Wind slabs have been stubborn to trigger, and will continue to gain strength over the coming days. Overall, snow instabilities will continue to be few and far between in the forecast area with any weakness in the snowpack hard to find.
For today, evaluate snow and terrain above treeline for any signs of wind loading on leeward S-SE-E-NE-N-NW aspects. Isolated terrain, primarily on open slopes 37 degrees and steeper, the tops of chutes and couloirs, near rock outcroppings (especially on SE aspects), depressions, and along roll overs/convexities, will be the places that one would find and potentially trigger a wind slab avalanche. Cold, shady, northerly facing aspects likely have the highest potential for wind slab trigger. Wind slabs on all aspects affected by sun will likely become more stubborn to trigger.
Climbing conditions are good for this time of year. Casaval, or one of the other ridge routes, would be a good option over the next few days for experienced climbers. Avalanche Gulch climbing conditions are good with relatively firm snow for decent boot packing. Boot penetration of just 5 cm was recorded at Helen Lake this last Thursday. That being said, the variable snow conditions will present a variety of surfaces to travel over. Some post holing is possible during the warmest portions of the day and at higher elevations in wind protected areas.
Pit profile at just under 9,000 ft. on the edge of Powder Bowl, Mt. Shasta-2/6/2016 by Forecaster:
Below: Wind effected snow conditions at upper 50/50 Flat on 2/4/2016 - 9,800 feet, Mt. Shasta
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LOCAL AREA ROAD, NORDIC and SNOWMOBILE PARK STATUS:
The Sand Flat cross country ski trails are in great shape and ready for your cross country skis or snow shoes. These are backcountry trails 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! These beautiful, groomed trails can be accessed via the Ski Park Highway. http://www.mtshastanordic.org
The Pilgrim Creek & Deer Mountain Snowmobile Parks are open! Trails are being groomed currently. 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 plowed to the lake. The Everett Memorial Highway is plowed to Bunny Flat.
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.
Weather and Current Conditions
Weather Summary
Good Morning! In Mt Shasta City at 0500, we have a current temperature of 35 F, two degrees cooler than yesterday at this time. Skies are fair with calm winds.
On Mt Shasta (South Side) in the last 24 hours...
Old Ski Bowl - 7,600 feet, the current temperature is 45 degrees F. Snow on the ground totals 116 inches with no new snow and 2 inches of settlement. Temperatures have ranged from 38 F to 53 F.
Grey Butte - 8,000 feet, the current temperature is 43 degrees F. Temperatures have ranged from 40 F to 49 F. Winds have been steadily increasing, averaging 15-30 mph, with a max gust to 56 mph, east.
Mt Eddy Range (West side of Interstate-5)...
Castle Lake - 5,600 feet, the current temperature is 44 degrees. Temperatures have ranged from 38 F to 51 F. Snow on the ground totals 64 inches with no new snow and no settlement.
Mt Eddy - 6,500 feet, the current temperature is 44 degrees F. Temperatures have ranged from 38 F to 51 F. Snow on the ground measures 81 inches with no new snow and 1 inch of settlement. Winds have averaged 3 mph, variable in direction with a max gust of 13 mph, west.
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.
| 0600 temperature: | 45 |
| Max. temperature in the last 24 hours: | 48 |
| Average wind direction during the last 24 hours: | Easterly |
| Average wind speed during the last 24 hours: | steadily increasing, 15-30 mi/hr |
| Maximum wind gust in the last 24 hours: | 56 mi/hr |
| New snowfall in the last 24 hours: | 0 inches |
| Total snow depth: | 94 inches |
Two Day Mountain Weather Forecast
Produced in partnership with the Medford NWS
| For 7000 ft to 9000 ft | |||
|---|---|---|---|
|
Monday (4 a.m. to 10 p.m.) |
Monday Night (10 p.m. to 4 a.m.) |
Tuesday (4 a.m. to 10 p.m.) |
|
| Weather | Sunny | Clear | Sunny |
| Temperature (°F) | 58 | 37 | 54 |
| Wind (mi/hr) | Southeast 15-29 mph | South 15-20 mph | South 10-15 mph |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
| For 9000 ft to 11000 ft | |||
| Monday | Monday Night | Tuesday | |
| Weather | Sunny | Clear and Breezy | Sunny and windy |
| Temperature (°F) | 40 | 38 | 34 |
| Wind (mi/hr) | Southeast 15-20 mph with gusts to 30+ mph | South 0 | Southwest 15-20 mph with higher gusts |
| Precipitation SWE / Snowfall (in) | / 0 | / 0 | / 0 |
