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The National Weather Service (NWS) is responsible for issuing severe weather watches, warnings and advisories to alert the public when dangerous weather conditions are expected.
Flood Potential Outlook - A flood potential outlook is issued when forecasted meteorological conditions indicate a significant heavy rainfall event may occur that would either cause flooding or aggravate an existing flooding situation. This long range outlook is usually issued 36-72 hours outlook prior to an event.
Hazardous Weather Outlook - A hazardous weather outlook is given when forecasters believe significant weather conditions are possible. An outlook is usually issued 48-72 hours in advance of an event.
Short Term Forecast - A short-term forecast describes the weather in the local area and includes a short-range forecast (usually not more than six hours). This product will be updated more frequently when it is used during active weather. A short-term forecast is sometimes referred to as a "NOW-cast."
Excessive Heat Watch - An excessive heat watch is issued when excessive heat is possible. Heat indexes are forecast at 105 degrees or higher for a period of two hours or more.
Fire Weather Watch - A fire weather watch is issued when there is the possible development of conditions favorable for forest, grass or brush fires.
Flash Flood Watch - A Flash Flood Watch is issued for potential rapid flooding from either torrential downpours, dam breaks, or ice jam breaks. They are usually issued up to 12 hours prior to a possible flash flood event.
Flood Watch - A flood watch is issued when the potential for flooding exists. The onset of flooding is much slower, usually greater than six hours, than a flash flood. They are usually issued up to 12 hours prior to the possible flood event.
High Wind Watch - A high wind watch is issued when there is a potential for dangerous winds.
Severe Thunderstorm Watch - A severe thunderstorm watch outlines an area where hail up to ¾-inch in diameter or larger, and damaging thunderstorm winds are expected to occur. In rare situations, the enhanced wording, "this is a particularly dangerous situation" will be used to describe extreme thunderstorm activity.
Tornado Watch - A tornado watch outlines an area where large hail and damaging wind threats, as well as the possibility of multiple tornadoes are possible. In rare situations, the enhanced wording, "this is a particularly dangerous situation" will be used when long-lived, strong and violent tornadoes are possible.
Excessive Heat Warning - An excessive heat warning is issued when heat indexes will reach 105 degrees or higher for a period of two hours or more.
Flash Flood Warning - A flash flood warning signifies a short duration of intense or rapid flooding of counties, communities, streams, or urban areas. Flash floods may result from such things as torrential downpours, dam breaks, or ice jam breaks.
Action: Take action immediately - move to higher ground, do not drive through flooded roadways.
Flash Flood Statement - A flash flood statement is issued after either a Flash Flood Watch or a Flash Flood Warning. It will provide the latest information on the flash flooding situation or event.
Flood Warning - A flood warning signifies a longer duration and more gradual flooding of counties, communities, streams, or urban areas. Floods usually begin after six hours of excessive rainfall.
Flood Statement - A flood statement is issued after either a Flood Watch or a Flood Warning. It will provide the latest information on the flash flooding situation or event.
High Wind Warning - A high wind warning is issued when sustained winds are predicted to reach 40 mph or greater for at least one hour, or any gust of wind is expected to be 58 mph or greater.
Severe Thunderstorm Warning - A severe thunderstorm warning is issued when large hail or damaging wind is actually occurring or imminent. Severe thunderstorms can produce tornadoes with little or no advance warning. Severe thunderstorms will also produce frequent and dangerous lightning.
Action: Seek safe shelter immediately. Criteria:
Hail - ¾" or larger; Wind - 58 mph or greater.
Severe Weather Statement - A severe weather statement provides follow-up information on severe weather conditions (severe thunderstorm or tornadoes) which have occurred or are currently occurring.
Special Marine Warning - A special marine warning is issued for any of the hazardous maritime weather conditions; thunderstorms over water; thunderstorms that will move over water; cold air funnels over water; or waterspouts usually two hours or less and producing sustained winds or frequent gusts of 34 knots or more.
Action: Boaters should move to safe
harbor.
Red Flag Warning - A red flag warning is issued when extreme burning conditions are forecasted. Forecasting criteria includes relative humidity, wind and temperature.
Action: No open burning.
River Flood Warning - A river flood warning is issued for specific communities or areas along a river where flooding is imminent or occurring. River flood warnings will provide crest forecasts.
Action: move to higher ground; do not
drive through flooded roadways
Tornado Warning - A tornado warning is issued if a cloud rotation has been spotted or when a tornado is imminent or occurring. This includes when a tornado is indicated by Doppler radar or sighted by spotters.
Action: Seek safe shelter immediately.
Dense Fog Advisory - A dense fog advisory is issued when widespread fog will reduce visibility to one-fourth mile or less.
Freezing Fog Advisory - A freezing fog advisory is issued when fog may reduce visibilities to less than one-fourth mile. In addition, the fog will freeze on exposed surfaces and cause black ice formation on roadways, bridges and sidewalks.
Action: Drivers should slow down and
use their headlights.
Heat Index (Apparent Temperature) - A number in degrees Fahrenheit that indicates how hot it feels when relative humidity is added to the actual air temperature. Exposure to direct sunlight can increase the heat index by 15 degrees.
NWS Heat Index Chart:
Heat Advisory - A heat advisory is issued when heat index is expected to reach at least 100°F but less than 105°F, or when nighttime lows are expected to remain above 80°F
Urban & Small Stream Flood Advisory - An urban and small stream flood advisory alerts the public to flooding which is generally an inconvenience. This advisory is issued when heavy rain is predicted to cause flooding of streets and low-lying places in urban areas. It is also used if small rural or urban streams are expected to reach or exceed their banks.
Wind Advisory - A wind advisory is issued when sustained winds are expected to be 40 mph or greater for at least an hour, or any wind gust between 45 mph and 57 mph.
Cold Air Funnels
Weak funnel cloud extensions from cumulous clouds that typically remain aloft. Cold air funnels form in cold, unstable air masses and are not usually associated with thunderstorms or severe weather.
Downburst
Intense gust of wind or downdraft that exits the base of a thunderstorm and spreads out horizontally at the earth's surface as a strong wind that often causes damage.
Flash Flood
A flood that can occur very rapidly. Flash floods occur as the result of very heavy rainfall in a short period of time, generally over a relatively small area.
Flood
A condition that occurs when water overflows the natural or artificial confines of a stream or body of water, or accumulates by drainage over low lying areas.
Funnel Cloud
A condensation funnel extending from the base of a towering cumulus cloud associated with a rotating column of air that is not in contact with the ground – and hence, different from a tornado. A condensation funnel is a tornado, not a funnel cloud if
a.) it is in contact with the ground;
b.) a debris cloud or dust whirl is visible beneath it.
Gust Front
The leading edge of a mass of cool, gusty air that flows from the base of a thunderstorm and spreads along the ground in advance of the thunderstorm.
Lightning
A visible electrical discharge produced by a thunderstorm. The discharge may occur within or between clouds, between the cloud and air, between a cloud and the ground or between the ground and a cloud.
Severe Thunderstorm
A thunderstorm producing a tornado, damaging winds of 58 mph or higher, and/or hail ¾ inch in diameter or larger.
Squall Line
A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorm.
Straight-Line Winds
Thunderstorm winds that may product damage that typically exhibits a lack of a rotational damage pattern. Straight-line winds are most often produced by a thunderstorm gust front, originating from a downburst.
Thunderstorm
In general, a local storm produced by a cumulonimbus cloud, and accompanied by lightning and thunder, usually with strong wind gusts, heavy rain and sometimes hail. A cumulonimbus cloud is a cauliflower-shaped cloud that has a height taller than or equal to its width.
Tornado
A violently rotating column of air that comes in contact with the ground, many times, descending from the base of a severe thunderstorm. Tornadoes are usually funnel-shaped with the narrow end nearest the ground. In Ohio, most tornadoes are obscured by hills, trees and rain.