NWS Jacksonville » Public Glossary

  • Dense Fog/Smoke Advisory - Issued when the visibility decreases to 1/4 mile or less in dense fog or smoke.
  • Wind Advisory - posted when wind speed is expected to be sustained 25 to 39 mph or any non-convective gusts of 40 to 57 mph are anticipated.
  • Dust Storm Warning - Issued when the visibility decreases to 1/4 mile or less and wind speeds of 25 mph or higher are occurring.  In such an episode, if the winds reach 40 mph or gust to 58 mph, then a dust storm warning and high wind warning will be issued.
  • Excessive Heat Warning - Issued when daytime high temperatures reach 105 degrees or higher with nighttime lows at or above 80 degrees for two consecutive days.
  • Freeze Warning - Issued when the air temperature is expected to be 32 degrees or below for 2 or more hours.  Issued as NPW and headlined in zone forecast.
  • Frost - The formation of ice crystals on the ground or other surfaces whose temperature has fallen below 32 degrees. A statement on its occurrence should be included in the body of the forecast. Examples: PATCHY FROST or SCATTERED FROST.  Frost can occur when the air temperatures are in the middle or upper 30s.
  • Hard Freeze - Temperatures 27 degrees or lower for 2 or more hours.
  • Heat Advisory - Issued heat if the heat index is expected to be 110 degrees or higher. Outside of advisory criteria, heat indices of greater than 100 degrees will be put in the zone forecast.
  • High Wind Warning - Issed when non-convective winds with sustained speeds of 40 mph or greater for one hour or longer or gusts to 58 mph or greater are expected.
  • Inland Hurricane Warning - High winds can occur a few hundred miles or so inland from the coast of a landfalling tropical cyclone.  Areas near the coast are covered with hurricane or tropical storm warnings.  However, hurricane and tropical storm warnings are not appropriate for inland areas since they are perceived to be associated with a marine environment and include storm surge dangers.  Therefore, tropical cyclone produced winds over inland areas are covered by an Inland Hurricane Warning.
  • Lake Wind Advisory - posted when wind speed is expected to be sustained 20 to 25 mph or any non-convective gusts of 30 to 39 mph are anticipated.
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