NWS Jackson, KY Warning & Advisory Criteria

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.

Special Weather Statement

• Thunderstorm wind gusts of 40 to 57 mph,
• AND/OR hail less than 1" in diameter,
• AND/OR frequent to continuous lightning,
• AND/OR 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 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 overland flooding that is expected to persist for many hours.

Flood Advisory

• Nuissance flooding including river/stream flooding and/or ponding of water in a geographic area 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 three hours or more.

Ice Storm Warning

• Damaging freezing rain accretions of ¼" or more.

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).

Wind Chill Warning

• Wind chills of -25°F or colder. (In most cases, a minimum wind speed equal to or greater than 10 mph should be forecast or occurring.)

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 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"
• 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.

Wind Chill Advisory

• Wind chills of -10°F to -24°F. (In most cases, a minimum wind speed equal to or greater than 10 mph should be forecast or occurring.)

Special Weather Statement

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

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

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.

Special Weather Statement

• Heat indices or wind chill 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.

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