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Avalanche Forecast for 2019-03-01 06:30

  • EXPIRED ON March 2, 2019 @ 6:30 am
    Published on March 1, 2019 @ 6:30 am
  • Issued by Ryan Sorenson - Mount Shasta Avalanche Center

The snowpack continues to settle and stabilize, however, uncertainty still exists for above treeline terrain. Cold temperatures with south and east wind could allow large windslabs to linger in isolated terrain.  Continued wind and available snow for transport will form new wind slabs in steep leeward terrain.  If venturing out proceed with caution today, potentially large and destructive avalanches are possible. 

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.

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

Avalanche Problem 1: Wind Slab

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Southerly and westerly winds have blown continuously at moderate speeds throughout the week.  Gray Butte has recorded an average wind speed of 9 mi/hr in the last 24 hours. Variable mountain winds and cross loading could allow wind slabs to form on all aspects today.   

The remains of large windslab avalanches were observed at Castle Lake yesterday. However unlikely, any lingering wind slabs from the last storm could produce large destructive avalanches. Old slide paths have begun to fill back in with new wind transported snow packing on top of the previous bed surface. New wind slabs have the potential to produce avalanches large enough to bury a person.

Continued caution and paying attention to where leeward areas reside will be necessary if venturing out into the backcountry today. Look for signs of wind slabs and cornices as you travel in safe terrain. Stay away from areas where shooting cracks, blocking, and whumphing are observed. Other signs of wind slabs include previously drifted snow and chalky, hollow sounding snow. If wind slabs are encountered keep travel to lower angle windward slopes to return to safety. 

Forecast Discussion

We have lots of great events this weekend. There will be an Avalanche Awareness presentation 7 p.m. tonight at the Shasta Mountain Guides store, 230 N Mt Shasta Blvd, Mount Shasta. Come to learn about the basics on safe travel, connect with the outdoor community, and get inspired to get outside in the winter. There will also be a companion rescue beacon clinic meeting at the Fifth Season; 300 N Mt Shasta Blvd, on Saturday, March 2, 2019 - 9:00am to 12:00pm. 

We are currently at 100% of normal for water this year thanks to the abnormally wet February. February received 216% of normal water totals for the month. 

Recent Observations

In the last 24 hours temperatures have varied, ranging from 8 to 27 degrees F near 7,600 feet on Mount Shasta. Winds have remained steady out of the west, averaging 10 mi/hr, with max wind speeds of 15 mi/hr and gusting up to 25 mi/hr at 8,000 feet. Temperatures at Castle Lake ranged from 15 to 38 degrees F in the last 24 hours near 5,800 feet. 



Conditions at Castle Lake yesterday:

  • Winds: Light, West
  • Temp: Increasing temps above freezing
  • Solar aspects softening in the afternoon. 
  • 2-3 inch (6-8cm) supportable melt freeze/rain crust dominates surface forms below 6,000 feet.
  • Softer right side up snowpack exists below the crust. 
  • A D3 avalanche released off of Left Peak breaking some trees and the ice on Castle Lake. For more information see our observation
  • Road: Everitt Memorial and Castle Lake Roads are closed.

View of Middle Peak Castle Lake Yesterday:

Note few avalanches occurred in this steep complex terrain compared to Left Peak (below). Lingering windslabs likely remain. 

Weather and Current Conditions

Weather Summary

An upper-level storm remains spinning off the Pacific Northwest coast and is slowly moving south and east today. This churning upheaval of air currently located to our Northeast is sending small waves of isolated snow showers and wind out of the south and east today. This weak system will bring little accumulation of snow. Expect isolated, short-lived snow showers throughout the weekend. 

Light wind will continue to blow out of the south this morning below and near treeline today. Moderate to strong wind out of the southwest will blow above treeline throughout the day on Mount Shasta. This will slow to light with moderate gusts this evening. The Eddies will see light to moderate wind from the south today. 

 

 

24 Hour Weather Station Data @ 6:00 AM

Weather Station Temp (°F) Wind (mi/hr) Snow (in) Comments
Cur Min Max Avg Avg Max Gust Dir Depth New Water Equivalent Settlement
Mt. Shasta City (3540 ft) 33 25 39 34.5 1 N
Sand Flat (6750 ft) station not responding
Ski Bowl (7600 ft) 16 8 29 19 185 0 0.04 5.8
Gray Butte (8000 ft) 15 11 27.5 19 9 25 W
Castle Lake (5870 ft) 22.5 15 38 25.5 148 1 4.4
Mount Eddy (6509 ft)
Ash Creek Bowl (7250 ft) station down
Ash Creek Ridge (7895 ft) station down

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Friday
(5 a.m to 11 p.m.)
Friday Night
(11 p.m. to 5 a.m.)
Saturday
(5 a.m to 11 p.m.)
Weather Becoming mostly cloudy with isolated snow showers. A 30 percent chance of snow. Mostly cloudy, chance of snow showers in the evening. A 40 percent chance of snow. Mostly cloudy then clearing. A 30 percent chance of snow.
Temperature (°F) 30 20 30
Wind (mi/hr) South 5-10 Southeast 5-10 Northeast 5-10
Precipitation SWE / Snowfall (in) / 0-1 / 0-2 / 0-1
For 9000 ft to 11000 ft
  Friday Friday Night Saturday
Weather Mostly cloudy with isolated snow showers. A 30 percent chance of snow. Mostly cloudy, chance of snow showers in the evening. A 40 percent chance of snow. Mostly cloudy then clearing. A 30 percent chance of snow.
Temperature (°F) 12 10 20
Wind (mi/hr) Southwest 20-25 Southwest 0-1 Southwest 10-15
Precipitation SWE / Snowfall (in) / 0-1 / 0-1 / 0-1

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2019 (the wet season) 29.53 29.50 100
Month to Date (since Apr 1, 2020) 15.60 7.23 216
Year to Date (since Jan 1, 2020) 21.12 14.29 148

Disclaimer

This forecast 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 forecast expires on midnight of the date it was posted unless otherwise noted.