Watch, Warning, and Advisory Headline Criteria at NWS Quad Cities

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Definition of NWS Quad Cities Warnings, Watches, and Advisories

Updated September 2024

Warnings | Watches | Advisories

For more on NWS Hazard Simplification, see here.

Warnings Conditions are occurring or imminent
Tornado	A severe thunderstorm has radar indications of intense low level rotation in the presence of atmospheric conditions conducive to tornado development, and/or is producing a tornado based on reports. These warnings are impact-based meaning they include a tornado tag and a tornado damage threat tag at the bottom of the warning. The tornado tag is either "Radar Indicated" or "Observed", with the latter giving confirmation a tornado has been reported with the storm. The tornado damage threat tag is for progressively worse expected damage and are "Considerable" and "Catastrophic". Wireless Emergency Alerts (WEAs) for smartphones are activated for all levels of Tornado Warnings.
Severe Thunderstorm	A severe thunderstorm or a line of severe thunderstorms capable of producing hail greater than one inch in diameter and/or 50 knot (58 mph) wind speeds. These warnings are impact-based meaning they include wind and/or hail tags and at times a damage threat tag at the bottom. The wind and/or hail tag is either "Radar Indicated" or "Observed", with the latter giving confirmation that severe weather has been reported with the storm. The damage threat tag is for progressively worse expected damage and are "Considerable" and "Destructive". Wireless Emergency Alerts (WEAs) for smartphones are activated for the "Destructive" level warning. An additional tag of "Tornado Possible" will be included when warning forecasters suspect a tornado is possible in addition to the damaging winds and/or hail.
Flood	Long duration areal flooding is occurring or is imminent, which may result from excessive rainfall, rapid snow melt, ice jams on rivers or other similar causes.
Flash Flood	Excessive rainfall producing thunderstorms have developed, leading to short duration flash flooding. A warning may also be issued if a dam break has occurred. These warnings are impact-based meaning they include a flash flood tag and at times a damage threat tag at the bottom. The flash flood tag will be either "Radar Indicated", "Gauge Indicated", or "Observed", with the last of those three giving confirmation that flash flooding has been reported with the storm. The damage threat tag is for progressively worse expected damage and are "Considerable" and "Catastrophic", in which Wireless Emergency Alerts (WEAs) for smartphones are activated for. An additional tag of "Expected Rainfall Rate" will be included when warning forecasters have enough confidence to include expected rainfall rates with the storm.
Blizzard	Wind speeds of 35 mph or greater, considerable falling or blowing snow, and visibilities frequently below a quarter mile are expected to prevail for three hours or more.
Winter Storm	Snow amounts of 6 inches or more during an event, which can't be longer than 48 hours and often are <24 hours. These may or may not be accompanied by heavy snowfall rates, wind, ice, falling temperatures, or other phenomena, but these factors are taken into consideration. A warning may be issued if conditions will be approaching blizzard criteria and/or have significant impacts, even if snowfall amounts are less (in some cases much less) than the criteria above.
Snow Squall	These are short-fused, smaller warnings (i.e. considerably smaller in space and time than Winter Storm Warnings) and issued for localized, intense areas of snow/wind expected to cause sharply reduced visibility of 1/4 mile or less often with sub-freezing road temperatures. These are not issued when Winter Storm or Blizzard Warnings are in effect. These can be General Snow Squall Warnings or Significant / High End Snow Squall Warnings, the latter of which will trigger Wireless Emergency Alerts (WEAs). For more, see here.
Ice Storm	Ice accumulations of a quarter inch or more are expected.
Extreme Cold	Widespread dangerous temperatures and/or wind chill values around -30° or colder are expected. (-25° or colder in far northeast Missouri and west central Illinois) For NWS criteria across the area click here.
Excessive Heat	When conditions are observed or anticipated for heat index readings to 105° or higher and a minimum heat index of 75°+ both for at least a two day period or four days of expected peak heat index readings forecast at 100° or higher.
Freeze	Widespread temperatures below freezing when during the growing season are expected.
High Wind	Air pressure gradient winds (those not associated with thunderstorms) or mesoscale winds associated with wake lows are expected to reach speeds of 40 mph or greater, sustained for at least one hour, or 58 mph or greater gusts.
Red Flag	This is intended primarily for land area managers but can assist communities in considering burn bans and citizens that they should not burn. This is issued when a combination of very dry air (often relative humidity <25%), windy conditions (often 25+ mph at 20 ft level), and very dry fuels (often <10% moisture). A multi-variable index taking the weather elements and vegetation status (through curing) into account is the Grassland Fire Danger Index (GFDI). When this is greater than 40, and considering other factors including fuel moisture, trends, and if available input from land area managers, we will issue a Red Flag Warning. We will also take into account dry croplands in the autumn.
Blowing Dust	Widespread, large scale-driven blowing dust reducing visibilities to 1/4 mile or less. Winds of 25 mph or greater are usually required. Generally this is in effect for a duration of longer than 90 minutes.

Watches Conditions are favorable but not occurring or imminent at the time
Tornado	Atmospheric conditions are favorable for the development of severe thunderstorms potentially capable of producing tornadoes. These Watches are initialized and coordinated by the NWS Storm Prediction Center.
Severe Thunderstorm	Atmospheric conditions are favorable for the development of severe thunderstorms, producing at least one inch diameter hail and/or 50 knot (58 mph) or greater wind speeds. These Watches are initialized and coordinated by the NWS Storm Prediction Center.
Flood	Atmospheric and hydrologic conditions are favorable for short duration flash flooding or longer duration areal flooding.
River Flood	Hydrologic conditions are favorable for upcoming river flooding in the next 24-60 hours, though there is uncertainty present.
Winter Storm	Severe winter storm conditions may occur, including heavy snow, significant ice or sleet accumulations, and in some cases potential for any of those to be accompanied by strong winds that may lead to significant visibility reductions.
Extreme Cold	Widespread dangerous temperatures and/or wind chill values around -30° or colder are possible. (-25° or colder in far northeast Missouri and west central Illinois) For NWS criteria across the area click here.
Excessive Heat	There is upcoming potential for heat index readings to 105° or higher for at least a two day period or four days of expected peak heat index readings forecast at 100° or higher.
Freeze	Widespread temperatures below freezing are possible during the growing season.
High Wind	The potential exists for air pressure gradient winds (those usually not associated with thunderstorms) or mesoscale winds associated with wake lows to reach speeds of 40 mph or greater, sustained for at least one hour, or 58 mph or greater gusts.
Fire Weather	This is intended primarily for land area managers but can assist communities in considering burn bans and citizens that they should consider not burning. This is issued often the day before the fire weather concern day when there is potential for a combination of very dry air (often relative humidity <25%), windy conditions (often 25+ mph at 20 ft level), and very dry fuels (often <10% moisture). A multi-variable index taking the weather elements and vegetation status (through curing) into account is the Grassland Fire Danger Index (GFDI). When this is near or greater than 40, and considering other factors including fuel moisture, trends, and if available input from land area managers, we will issue a Fire Weather Watch which may be upgraded to a Red Flag Warning if confidence increases. We will also take into account dry croplands in the autumn.

Advisories Conditions are occurring or imminent
Special Weather Statement	A thunderstorm or line of thunderstorms has developed and is capable of producing hail and gusty winds that approach but are below severe weather criteria, such as dime to nickel size hail and 40 to 55 mph winds.
Winter Weather	Any one of a combination of the following winter weather elements is expected: ~3 to 5 inches of snow, light sleet accumulation, light ice accumulation, and localized significant visibility reductions due to snow and/or blowing snow. This can also be issued when less snow accumulation may lead to impacts, such as during commute times, cold temperatures and flash freeze conditions, and any other situation where the forecaster deems necessary.
Cold Weather	Widespread temperatures and/or wind chill values around -20° to -29° are expected. (-15° to -24° in far northeast Missouri and west central Illinois) For NWS criteria across the area click here.
Heat	Maximum heat index is expected to exceed 100°.
Frost	Widespread temperatures of 33 to 36 degrees with favorable conditions for frost are expected during the growing season.
Wind	Sustained winds of 30 to 39 mph and/or gusts of 45 mph or stronger are expected to last for at least one hour.
Dense Fog	Widespread visibility of a quarter mile or less is expected.
Freezing Fog	Widespread (not just patchy) light ice accumulation is expected from freezing fog.
Blowing Dust	Widespread, large scale-driven blowing dust reducing visibilities to one mile or less, but greater than 1/4 mile. Winds of 25 mph or greater are usually required. Generally this is in effect for a duration of longer than three hours.

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