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...CALL US!


...NWS Winter Storm/Weather Criteria...

...Mountains and Foothills Criteria...

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



...Urban Corridor & Plains Criteria ....
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 criteria must
continue for 3 hours or longer:

   sustained winds of 35 mph or greater
and
   visibilities frequently less than 1/4 mile
and
   Considerable snow and/or blowing snow

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