NWS Jackson, KY Warning or Advisory Criteria

Criteria may be adjusted in certain circumstances to take into account
the expected impact of an event.

Severe Weather Events...
  • Severe Thunderstorm Warning
    • Thunderstorm wind gusts of 58 mph or greater,
    • AND/OR hail measuring 1" in diameter or larger.
  • Tornado Warning
    • Tornado observed or indicated on radar.

Winter Weather Events...
  • Blizzard Warning
    • Sustained wind or frequent gusts of 35 mph or higher,
    • AND visibility less than 1/4 mile in snow and/or blowing snow for 3 hours or longer.
  • Ice Storm Warning
    • Damaging ice accumulations of 1/4" or more.
  • Winter Storm Warning
    • Snowfall of 4" or more in 12 hours or 6" or more in 24 hours,
    • OR sleet accumulation of 1/2" or more in 24 hours.
  • Winter Weather Advisory
    • Snowfall of at least 1" but less than 4" in a 12 hour period,
    • AND/OR visibility reduced to 1/4 mile or less in blowing snow,
    • AND/OR sleet accumulation of less than 1/2".
  • Freezing Rain Advisory
    • Ice accumulations of less than 1/4".
  • Wind Chill Warning
    • Wind chills of 25 below or colder are expected. In most cases a minimum wind speed of 10 mph should be occurring or forecast before a warning is issued.
  • Wind Chill Advisory
    • Wind chills of 10 below to 24 below are expected. In most cases a minimum wind speed of 10 mph or more should be occurring or forecast before an advisory is issued.

Non-Precipitation Events...
  • High Wind Warning
    • Sustained non-thunderstorm wind speeds of at least 40 mph for an hour or more,
    • OR non-thunderstorm wind gusts of at least 58 mph regardless of duration.
  • Wind Advisory
    • Sustained non-thunderstorm wind speeds between 30 and 39 mph for at least one hour,
    • OR non-thunderstorm wind gusts of 40 to 57 mph for any duration.
  • Lake Wind Advisory
    • Issued when sustained non-thunderstorm wind speeds reach 20 to 29 mph for at least one hour,
    • OR non-thunderstorm wind gusts reach between 35 to 39 mph.
  • Freeze Warning
    • Widespread temperatures are forecast to be 30ºF or below for 2 hours or more during the growing season.  The beginning of the spring frost/freeze season and ending of the fall frost/freeze season is determined in conjunction with the University of Kentucky Agricultural Weather Center.
  • Frost Advisory
    • Widespread frost during the growing season.  The beginning of the spring frost/freeze season and ending of the fall frost/freeze season is determined in conjunction with the University of Kentucky Agricultural Weather Center.
  • Excessive Heat Warning
    • Issued when the heat index is expected to reach around 110ºF or higher,
    • AND the minimum heat index will remain around 75ºF or higher during a 48 hour period.
    • A warning would also be appropriate if heat advisory criteria are expected to be reached for 4 consecutive days.
  • Heat Advisory
    • Issued for heat index of around 105ºF
  • Dense Fog Advisory
    • Widespread visibility 1/4 mile or less due to dense fog.
  • Dense Smoke Advisory
    • Widespread visibility 1/4 mile or less due to dense smoke.
  • Dust Storm Warning
    • Widespread visibility 1/4 mile or less due to blowing dust.
  • Blowing Dust Advisory
    • Widespread visibility of between 1/4 mile and 1 mile.

Fire Weather Events...
  • Red Flag Warning
    • Sustained 20-foot wind speeds of 15 mph or greater,
    • AND minimum relative humidity of 25% or less,
    • AND 10-hour fuel moisture values of 8% or less.

National guidance regarding NWS Watch/Warning/Advisory products can be found in the following NWS Directives:
NWSI 10-511 WFO Severe Weather Products Specification,
NWSI 10-513 WFO Winter Weather Products Specifications,
NWSI 10-515 WFO Non-Precipitation Weather Products Specification,
NWSI 10-401 Fire Weather Services Product Specification


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