Winter Guidelines and NWS Winter Criteria

 

Winter Guidelines for calling WFO Boulder

  • 12 and/or 24 hour snow depth and new snowfall by 8 AM and 8 PM.

  • Moderate to heavy snowfall.

    • Example: 1/2-1 inch per hour for several hours and visibilities less than 1/2 mile.

  • Strong winds above 50 mph (sustained or gusts).

  • Freezing rain/drizzle (any intensity).

  • Report changeover from rain to snow or from snow to rain.

  • Dense Fog (visibility less than a quarter of a mile).

  • If current conditions do not coincide with the current WFO Boulder Forecast.

  • Adverse road conditions.

  • If any of the below snow criterion is met.

  • **Our criteria for issuing warnings and advisories are listed above.   Please pay close attention to when

     your snowfall approaches 4 inches and again at 8 inches at the higher elevations (at or above 6500 feet).    

    3 and 6 inches are the critical numbers for the stations at lower elevations (below 6500 feet).

  • Still in doubt, simply call us.

 

NWS Winter Storm/Weather Criteria - Mountains and Foothills

  • Winter Storm Warning

    • 8 inches or more in a 12 hour period.

    • 12 inches or more in a 24 hour period.

  • Snow Advisory

    • 4 to 7 inches in a 12 hour period.

  • High Wind Criteria

    • Sustained winds of 50 mph or greater OR

    • Wind gusts to 75 mph or more

 


NWS Winter Storm/Weather Criteria - Urban Corridor and Plains

  • Winter Storm Warning

    • 6 inches or more in a 12 hour period.

    • 8 inches or more in a 24 hour period.

  • Snow Advisory

    • 3 to 5 inches in a 12 hour period.

  • High Wind Criteria

    • Sustained winds of 40 mph or greater OR

    • Wind gusts to 58 mph or more

  • Blizzard Criteria (The following 3 criteria must continue for 3 hours or more)

    • Sustained winds of 35 mph or greater

    • Visibilities grequently less than ¼ mile

    • Considerable snow and/or blowing snow

 


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.