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Avalanche Forecast for 2019-01-08 06:30

  • EXPIRED ON January 9, 2019 @ 6:30 am
    Published on January 8, 2019 @ 6:30 am
  • Issued by Aaron Beverly - Mount Shasta Avalanche Center

Avalanche danger will increase to HIGH as two or more feet of new snow is expected to fall above treeline. Wind slabs likely exist above treeline and will continue to grow to significant size. Wet conditions near and below treeline will raise concern for storm slab and loose wet problems. Dangerous winds and wet weather will present challenging conditions today.

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

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

Forecast Hotline: (530) 926-9613

Avalanche Problem 1: Wind Slab

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Wind slabs have formed on northerly slopes and will continue to grow to several feet thick with the significant snow and south winds predicted today. Look for them primarily on northerly aspects.

These slabs may sit atop icy surfaces and crusts and will be reactive. Expect them primarily above treeline on north facing aspects. But look for them everywhere. Visual clues that indicate winds slabs are nearby are fresh cornices, blowing snow, snow drifts, and uneven snow surfaces. Avoid wind loaded slopes over 35 degrees. 

Avalanche Problem 2: Storm Slab

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Storm slabs don't linger for long, but with the rain and heavy snow expected today and tomorrow, these could become reactive again. Look for them near and below treeline.

Storm Slabs form when new snow consolidates over a weaker layer or interface. They tend to have a short life span. They are easiest to trigger during periods of heavy snow and typically stabilize within a day or two after the storm cycle has ended.

Stay away from convex rollovers, unsupported slopes, and slopes over 40 degrees. This problem will be confined to protected areas below and near treeline.

Avalanche Problem 3: Loose Wet

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Inches of water on light dry snow could create conditions ripe for loose wet avalanches. Look for them below treeline.

Loose Wet avalanches form in new snow or old surface snow that is warming. Warming temperatures, strong solar radiation, or rain-on-snow make the surface snow damp or wet. As the water content increases, the snow becomes unconsolidated. They start at a point and entrain additional snow as they move down hill, and have a characteristic fan-like shape.

Forecast Discussion

Significant rain and heavy snow will make things interesting today and tomorrow. These conditions will do nothing to contribute to snowpack stability in the short term. Old storm slabs could become reactive again. Look for loose wet conditions below and near treeline. Feet of snow above treeline will add a lot of weight to the the snowpack and wind slabs will continue to grow.

Avalanche danger remains elevated at all elevations. If you venture out, keep in mind the 5 red flags indicating avalanche danger:

  • Recent avalanche activity
  • Cracking, blocking, or whoomphing
  • Significant snowfall in 24 hours *
  • Strong winds *
  • Rapid warming

* - will happen today.

Recent Observations

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Total snow accumulation during storms on Saturday and Sunday was 25 inches. We have received a couple of inches of snow in the last 24 hours at the Old Ski Bowl. Westerly winds have been light. Temperatures have ranged from 14 to 30 degrees F.

No notable wind effects were seen below and near treeline yesterday. Whiteout conditions prevented any detailed investigation of the upper mountain, though brief glimpses seemed to indicate that strong winds blew snow towards the north during the weekend. No avalanches were seen.

Snowpack continues to show a right side up configuration with no concerning column test results. Sugary snow exists below a crust near the new/old snow interface close to a meter down, but failures there were difficult to trigger. The crust was not widespread.

Weather and Current Conditions

Weather Summary

Wet and wild conditions will prevail today and tomorrow as a massive low pressure system off the coast impacts the area. Strong to gale force winds will blow from the south. Close to 4 inches of precipitable water is expected by Thursday morning, with the most intense battering coming after 4 p.m. today. Feet of snow is expected near and above treeline. High snow levels will destroy our snow pack below 6000 feet.

A flood watch is in effect through late Wednesday night. A lull in wet conditions is now expected from Friday to early next week.

24 Hour Weather Station Data @ 5:00 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) 39 29 39 35 1 N
Sand Flat (6750 ft) 33 16 33 28 55 1 0 2
Ski Bowl (7600 ft) 30 14.5 31 24 65.4 2.4 0.47 2.3
Gray Butte (8000 ft) 28 13.5 30 23 11 25 W
Castle Lake (5870 ft) station down
Mount Eddy (6509 ft) 32.5 17 33 28.5 2 14 SSW 47.5 6
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
  Tuesday
(4 a.m. to 10 p.m.) 		Tuesday Night
(10 p.m. to 4 a.m.) 		Wednesday
(4 a.m. to 10 p.m.)
Weather Rain and snow. The rain and snow could be heavy at times. Windy and gusty. Chance of precipitation is 100%. Rain and snow, becoming all snow after 10 p.m. The rain and snow could be heavy at times. Windy and gusty. Chance of precipitation is 100%. Snow. Windy and gusty. Chance of precipitation is 100%.
Temperature (°F) 36 30 35
Wind (mi/hr) South 35-40 South 20-30 South 10-20
Precipitation SWE / Snowfall (in) / 3-8 / 7-15 / 5-11
For 9000 ft to 11000 ft
  Tuesday Tuesday Night Wednesday
Weather Snow. The snow could be heavy at times. Very windy and gusty. Low wind chills. Chance of precipitation is 100%. Snow. The snow could be heavy at times. Low around 17. Dangerous winds. Gusty. Below zero wind chills. Chance of precipitation is 100%. Snow. The snow could be heavy at times. Dangerous winds. Gusty. Below zero wind chills. Chance of precipitation is 100%.
Temperature (°F) 25 17 17
Wind (mi/hr) South 50-60 South 7-12 South 45-55
Precipitation SWE / Snowfall (in) / 7-12 / 19-25 / 11-17

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2023 (the wet season) 10.07 16.86 60
Month to Date (since Apr 1, 2024) 1.66 1.65 101
Year to Date (since Jan 1, 2024) 1.66 1.65 101

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.