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Avalanche Forecast for 2020-04-09 06:21

  • EXPIRED ON April 10, 2020 @ 6:21 am
    Published on April 9, 2020 @ 6:21 am
  • Issued by Nick Meyers - Shasta-Trinity National Forest

Today will be the warmest day of the week.  Above freezing overnight temperatures and very warm daytime high's raise concern for loose wet avalanches on those sunny, southerly aspects. The recent storm snow has settled out well but surface layers of the snow still remain heavy and wet. Human triggered, loose-wet avalanches are possible.

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

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.

Avalanche Problem 1: Loose Wet

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Poor overnight re-freeze and above normal daytime temperatures will contribute toward a chance for loose-wet avalanches today. Heavy, mushy, unconsolidated snow surfaces exist, despite about 6 inches (15 cm) of storm snow settlement. Loose wet avalanches may not be big enough to bury you, but could sweep you into undesirable terrain. If you see rollerballs and/or pinwheels occurring naturally or off your ski turns, it's time to head back to the barn or pick another slope that is less sun affected. Loose-wet avalanches often start at a point and entrain more snow as they move downhill. These type of avalanches are usually small and harmless, but can gain significant size and momentum on large slopes with a long fetch. 

Avalanche Problem 2: Cornice

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Any remaining cornices along ridgelines/bowls out there will become weak during this period of warm weather. Several crumbling cornices were observed yesterday. This is the time of year when they begin to break off. Don't be part of that. Simply, identify terra firma by looking for rocks and trees sticking up through the snowpack and plan your travel route accordingly. Cornices can and will break without any warning and can often fracture back further than expected. Hairy side up folks!

Forecast Discussion

The Shasta/Trinity National Forest is under COVID-19 Restrictions. Please obey. It takes a village.

Recent Observations

  • Yesterday was a warm one but breezy conditions kept loose wet snow instabilities intact.
  • Blowing snow was observed spooling off ridgelines on the upper mountain due to strong northeasterly wind. Heavy, wet snow below 11,000 feet was not conducive for wind transport.
  • Near treeline temperatures peaked at 46.5 degrees yesterday from 1600 to 1800 hours. Today will be warmer. Temperatures have remained well above freezing throughout the night, dropping only to 40.5 degrees.
  • The upper snowpack is moist and sticky. Numerous rollerballs and small point releases were seen on steep east, south and west facing aspects below and near treeline.
  • Old crown lines continue to be found from the recent avalanche cycle previously in the week, including a report (picture below) of an avalanche outrun by a snowmobiler. Nobody was caught or injured. Location looks like the northwest bowl of Ash Creek Butte.

     

Weather and Current Conditions

Weather Summary

It's going to be high and dry with full sun today. Warmer than normal conditions are expected with peak temperatures for the week. Afternoon high's will be 15 to 20 degrees above normal. Above treeline in exposed areas and high in the alpine, anticipate north/northeasterly wind, 10 to 20 mi/hr with gusts higher. Deep northerly flow continues over the region through next week, meaning dry conditions and temps above normal. Wind will persist through the weekend.

24 Hour Weather Station Data @ 4:00 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) 37 37 71 53.5 3 N
Sand Flat (6750 ft) 34 28 54 40 55 0 0 5
Ski Bowl (7600 ft) 44.5 37 46.5 42.5 90.8 0 0 5.2
Gray Butte (8000 ft) 43.5 36.5 46.5 42.5 19 43 E
Castle Lake (5870 ft) 41 38.5 58.5 50 48.3 0 4.2
Mount Eddy (6509 ft) 41 35 55 46 2 10 WSW 65.9 0 5.6
Ash Creek Bowl (7250 ft) down
Ash Creek Ridge (7895 ft) down

Two Day Mountain Weather Forecast

Produced in partnership with the Medford NWS

For 7000 ft to 9000 ft
  Thursday
(5 a.m to 11 p.m.)
Thursday Night
(11 p.m. to 5 a.m.)
Friday
(5 a.m to 11 p.m.)
Weather Sunny. Clear. Sunny.
Temperature (°F) 56 35 52
Wind (mi/hr) Northeast 5-10 Northwest 5-10 Northwest 5-10
Precipitation SWE / Snowfall (in) 0.00 / 0 0.00 / 0 0.00 / 0
For 9000 ft to 11000 ft
  Thursday Thursday Night Friday
Weather Sunny. Windy. Clear. Windy. Sunny. Windy.
Temperature (°F) 34 31 32
Wind (mi/hr) East/Northeast 20-30 North/Northeast 15-20 North 15-20
Precipitation SWE / Snowfall (in) 0.00 / 0 0.00 / 0 0.00 / 0

Season Precipitation for Mount Shasta City

Period Measured (in) Normal (in) Percent of Normal (%)
From Oct 1, 2019 (the wet season) 17.17 36.37 47
Month to Date (since Aug 1, 2020) 2.00 0.91 220
Year to Date (since Jan 1, 2020) 8.24 21.16 39

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 24 hours after the posted time unless otherwise noted.