Turncarver

Mountain Conditions - Mt St Helens

 V2_2609031654

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Mt St Helens

Marble Mountain Sno Park: Latitude: 46.13077, Longitude: -122.16968, Elevation: 2,672 ft

Links to Additional Information

• Other Locations on this Page
  • Top of Page
  • Mt St Helens
  • Misc Information
• National Volcanic Monument
  • Mt St Helens Info
  • Johnston Ridge Observatory
  • Mt St Helens Climbing Permits
• Misc Information
  • Mt St Helens Institute - Current Conditions
• National Weather Service
  • National Weather Service (NWS) Forecast Site
  • Current Station Snow Conditions
• Other Weather Sites
  • Weather.com Radar for Cougar WA
  • Mountain-Forecast.com Weather for Mt St Helens
• Northwest Avalanche Center
  • Northwest Avalanche Center (NWAC) Avalanche Forecast: West Slopes South
  • Northwest Avalanche Center (NWAC) Weather Forecast
  • NWAC Mt St Helens Weather Station Data Telemetry Graph
  • NWAC Mt St Helens Weather Station Data Telemetry Table
• WA Department of Transportation
  • WSDOT Real Time Map
  • Mountain Pass Information
  • WA State Highway Cameras
• Mt St Helens Sno Parks
  • Marble Mountain Sno Park
  • S. Cascades Non-Motorized Sno Parks
  • Climbers Bivouac Trailhead
  • Non-motorized Sno Park Passes

Marble Mountain Sno Park Webcams and Forecast

Mt St Helens Upper Slopes Forecast

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Legend / Misc Information

• Other Locations on this Page
  • Top of Page
  • Mt St Helens
  • Misc Information

Weather Terminology

• National Weather Service Glossary
• NOAA National Severe Storms Laboratory Learning Resources
  • NNSSL Severe Weather 101
  • NNSSL Learning Resources for Everyone
• National Weather Service - Varying Types of Winter Weather

Interpreting wind data graphics

Wind is plotted in increments of 5 knots (kts), with the outer end of the symbol pointing toward the direction from which the wind is blowing. Flags at a the end of the symbol indicate the wind speed. The wind speed is determined by adding up the total of the flags, lines, and half-lines, each of which have the following individual values:

Flag: 50 kts
Line: 10 kts
Half-Line: 5 kts

1 knot = 1 nautical mile per hour = 6076 feet per hour = 1.15 mile per hour.

More complete guidance for interpreting weather station graphics can be found on the NWS website.

More information about wind speeds and the Beaufort Scale can be found at the MetService Blog or the Windy Beaufort Scale page.

Interpreting NWS precipitation Probabilities

The National Weather Service (NWS) weather tables sometimes contain bar charts that use the following notation to indicate the probability of Rain, Thunder, Snow, Freezing Rain, or Sleet.

Ocnl: Occasional (80% - 100%) Lkly: Likely (60% - 70%) Chc: Chance (30% - 50%) SChc: Slight Chance (10% - 20%) [None]: <10%

Rain Amount Guidelines

1/100 (0.01) of an inch of rain – The first measurable amount of rainfall reported by The National Weather Service. This would not leave puddles on the ground and would slightly wet the surface. This might occur during a light shower for 2-5 minutes or even a drizzle for 2 hours.

1/10 (0.10) of an inch of rain – A light rain for 30-45 minutes, moderate rain for 10 minutes or heavy rain for 5 minutes. Small puddles would form but usually disappear after a short while.

1/4 (0.25) of an inch of rain – A light rain for 2-3 hours, moderate rain for 30-60 minutes or heavy rain for 15 minutes. There would be many puddles on the ground and they would not disappear easily.

1/2 (0.5) of an inch of rain – A light rain never reaches this amount, moderate rain for 1-2 hours or heavy rain for 30-45 minutes. There would be deep standing water and they would last for long periods of time.

3/4 (0.75) of an inch of rain – A light moderate rain never reaches this amount, heavy rain lasting for 2-4 hours. There would be deep standing water for long periods of time.

One (1.00) inch of rain – A light moderate rain never reaches this amount, heavy rain for several hours (2-5 hours). There would be deep standing water for long periods of time.