NWS Jackson, KY Warning and Advisory Product Criteria

NWS Jackson, KY Warning or Advisory Criteria

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.

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 2" 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".

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 45 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 44 mph.
Freeze Warning
- Widespread temperatures 32ºF or below during the growing season.
Frost Advisory
- Widespread frost during the growing season.
Excessive Heat Warning
- Issued when the heat index is expected to reach 105ºF 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 100ºF
- OR actual maximum air temperatures of 95ºF or higher.
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.

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 Weather Service Weather Forecast Office