NWS Jackson, KY Warning & Advisory Criteria

Severe Thunderstorm Warning

• Radar or satellite indicate and/or reliable reports of thunderstorms with:
  • ​Wind gusts equal to in excess of 58 mph
  • AND/OR hail size of 1 inch (U.S quarter size) in diameter or larger.

Tornado Warning

• Radar indication and/or reliable reports of tornado or developing tornado.

Special Weather Statement

• Strong thunderstorms that approach, or expected to approach severe criteria.
  • ​A strong thunderstorm contains one or combination of the following events:
    1. Wind gusts of 40 to 57 mph
    2. Hail less than 1 inch in diameter
    3. Frequent to continuous lightning
    4. Landspouts that are not anticipated to threaten lives and/or property
    5. Funnel clouds not expected to become a tornado threat

See NWSI 10-511 WFO Severe Weather Products Specification for additional information.

Flash Flood Warning

• Life or property-threatening, short-term rapid onset flooding is imminent or occurring. This can include flooding due to heavy rainfall or due to a dam or levee break.

Flood Warning

• Flooding due to potentially damaging river level rises,
• OR damaging overland flooding that is expected to persist for many hours.

Flood Advisory

• Nuisance flooding due to river level rises and minor overland flooding and/or ponding of water that warrants notification of the public but less urgent than a warning.

Special Weather Statement

• Heavy rainfall that is expected to cause hazardous travel conditions but is not expected to cause flooding.

See NWSI 10-922 WFO Hydrologic Products Specification for additional information.

Blizzard Warning

• Sustained wind or frequent gusts greater than or equal to 35 mph accompanied by falling
• AND/OR blowing snow, frequently reducing visibility to less than ¼ mile for 3 hours or more.

Ice Storm Warning

• Ice accumulation of of ¼" or more on an elevated horizontal flat surface.

Snow Squall Warning

• Heavy snow and gusty winds reducing visibility to ¼ mile or less with sub-freezing ambient road surfaces
• AND/OR plunging temperatures behind an arctic front sufficient to produce flash freezes, along with a significant reduction in visibility from falling and/or blowing snow
• AND at least a risk for a flash freeze.

Winter Storm Warning

• Heavy snow accumulation of 4" or more within 48 hours or less
• AND/OR sleet accumulation of ½" or more
• AND/OR mixed precipitation with at least one winter hazard type (blizzard, freezing rain, sleet, or snow) meeting or exceeding warning criteria
• OR high impact frozen precipitation outside of the normal winter season or during a critical situation (standard criteria not being met, but impacts are expected to be unusually significant).

Winter Weather Advisory

• Snow accumulations of between 1 and 4", or impacts expected with 1" or less of snow
• AND/OR Freezing rain accretions less than ¼" on an elevated horizontal flat surface
• AND/OR Sleet accumulation less than ½"
• AND/OR Black ice causing widespread slick roads and/or numerous accidents
• AND/OR Blowing snow that reduces visibilities to ¼ mile or less.

Special Weather Statement

• Black ice,
• OR short-duration heavy snow bands below warning criteria.

See NWSI 10-513 WFO Winter Weather Products Specifications for additional information.

Blowing Dust Warning

• Widespread synoptically driven blowing dust reducing visibilities to ¼ mile or less
• AND winds of 25 mph or greater usually required
• AND generally for a duration of longer than 90 minutes.

Blowing Dust Advisory

• Widespread synoptically driven blowing dust reducing visibilities to 1 mile or less but greater than ¼ mile
• AND winds of 25 mph or greater usually required
• AND generally for a duration of longer than 90 minutes.

Dust Storm Warning

• Dust storm reducing visibility to ¼ mile or less, with sudden reduction in visibility
• AND winds of 25 mph or greater usually required
• AND typically localized and brief in duration.

Dust Advisory

• Dust reducing visibility to 1 mile or less but greater than ¼ mile, with sudden reduction in visibility
• AND winds of 25 mph or greater usually required
• AND typically localized and brief in duration.

Excessive Heat Warning

• Maximum heat index around 110ºF or higher
• AND the minimum heat index will remain around 75ºF or higher
• AND conditions persist for at least 48 hours;
• OR Heat Advisory criteria is to be met for 4 consecutive days.

Heat Advisory

• Maximum heat index of around 105ºF or higher for up to 3 consecutive days.

Extreme Cold Warning

• Air temperatures or wind chill values reaching or exceeding the county-level warning criteria (displayed below).

Cold Weather Advisory

• Air temperatures or wind chill values reaching or exceeding the county-level warning criteria (displayed below).

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Freeze Warning

• Minimum shelter temperature to be under 30ºF for 2 hours or more during the growing season. The beginning and end of the growing season are determined in conjunction with the University of Kentucky Agricultural Weather Center.

Frost Advisory

• Widespread frost during the growing season. The beginning and end of the growing season are determined in conjunction with the University of Kentucky Agricultural Weather Center.

High Wind Warning

• Sustained non-thunderstorm wind speeds of at least 40 mph for 1 hour or more
• OR non-thunderstorm wind gusts of 58 mph or greater for any duration.

Wind Advisory

• Sustained non-thunderstorm wind speeds of 30 and 39 mph for at least 1 hour
• OR non-thunderstorm wind gusts of 40 to 57 mph for any duration.

Lake Wind Advisory (for Lake Cumberland, Laurel Lake, and Cave Run Lake only)

• Sustained non-thunderstorm wind speeds of 20 to 29 mph for at least 1 hour
• OR non-thunderstorm wind gusts of 35 to 39 mph.

Dense Fog Advisory

• Widespread fog reducing visibility to ¼ mile or less
• OR localized fog reducing visibility to ¼ mile or less producing major impacts.

Dense Smoke Advisory

• Widespread smoke reducing visibility to ¼ mile or less
• OR localized smoke reducing visibility to ¼ mile or less producing major impacts.

Freezing Fog Advisory

• Freezing fog producing light ice accretion and slippery conditions.

Special Weather Statement

• Heat indices, wind chill or air temperature values near "advisory" level for an hour or two,
• OR local areas of dense fog, dense smoke or other hazards that are below advisory criteria.

See NWSI 10-515 WFO Non-Precipitation Weather Products Specification for additional information.

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.

Special Weather Statement

• Low confidence or borderline red flag conditions:
  1. ​Critically low relative humidity values
  2. Near criteria wind gusts
  3. Marginal 10-hour fuel moistures

See NWSI 10-401 Fire Weather Services Product Specification for additional information.