“WATCH” – The conditions are favorable for severe weather to occur. Persons in or close to the watch area should remain alert to threatening weather conditions.
“WARNING” – Severe weather has been sighted and/or indicated. Persons in the warned area should take cover immediately and remain in a safe place until the warning expires or is cancelled by the local authorities.
A TORNADO WATCH means that conditions are right for a tornado to develop. You should listen to NOAA Weather Radio, or to commercial radio and television stations for the latest weather information. Keep informed! Keep an eye out for threatening conditions and be prepared to go to a safe place.
A PDS WATCH (Particularly Dangerous Situation) is a type of enhanced wording used by the National Weather Service’s Storm Prediction Center in Norman, Oklahoma on certain weather watches. It is issued at the discretion of the forecaster writing the watch and implies that there is an enhanced risk of very severe and life-threatening weather, usually a major tornado outbreak or (much less often) a long-lived, extreme derecho event (see below).
A TORNADO WARNING means that a tornado has been detected by radar of seen by someone. If the tornado warning is for your area, then you should go to a safe shelter immediately.
A TORNADO EMERGENCY is issued when a large, violent tornado is expected to impact a populated area, or confirmed damage is an ongoing event.
A SEVERE THUNDERSTORM is a thunderstorm producing winds of 58 miles per hour or greater and/or 1 inch or larger hail (Updated JAN 2010). Thunderstorms are also classified as severe if they produce tornadoes.
A SEVERE THUNDERSTORM WATCH means that conditions are right for a severe thunderstorms to develop. You should listen to NOAA Weather Radio, or to commercial radio and television stations for the latest weather information. Keep informed! Keep an eye out for threatening conditions and be prepared to go to a safe place.
A SIGNIFICANT WEATHER ALERT is issued when Doppler weather radar indicates a strong thunderstorm is producing small hail or high winds whose strength does not reach severe thunderstorm criteria. It does not necessarily account for lightning or flooding.
A SEVERE THUNDERSTORM WARNING means that a severe thunderstorm has been detected by radar of seen by someone. If the thunderstorm warning is for your area, then you should go to a safe shelter immediately. Tornadoes often develop from severe thunderstorms.
A FUNNEL CLOUD is a cloud, shaped like a funnel, extending from the base of a thunderstorm, but not making contact with the ground. Funnel clouds are associated with rotating columns of air. When a funnel cloud makes contact with ground, it is re-classified as a tornado.
A TORNADO is a violently rotating column of air contact with the ground. Tornadoes are most often found in the Southwest quadrant of the thunderstorm, especially super cells.
A WALL CLOUD is a local and often abrupt lowering of a rain-free cloud base, usually situated in the Southwest portion of a storm below an intense updraft. Wall clouds are often associated with very strong or severe thunderstorms. Rotating wall clouds usually develop before tornadoes or funnel cloud form, from a few minutes up to possibly an hour. Wall clouds are often flat, low hanging and dark. Sometimes, other low-hanging accessory clouds are mistakenly identified as wall clouds.
A DERECHO (from Spanish: “derecho” meaning “straight”) is a widespread and long-lived, violent convectively induced straight-line windstorm that is associated with a fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo.
A WINTER WEATHER ADVISORY is issued by the National Weather Service of the United States when a low pressure system produces a combination of winter weather (snow, freezing rain, or sleet) that presents a hazard, but does not meet warning criteria. A Winter Weather Advisory is similar to significant weather alert, though a winter weather advisory is an official product. A “Winter Weather Advisory” means the a period of winter weather will make traveling difficult.
A WINTER STORM WATCH is issued when there is a potential for heavy snow (6 or more inches) or significant ice accumulations. The watch is usually issued at least 24 to 36 hours before the storm’s arrival in the area. The criteria for this watch can vary from place to place.
A WINTER STORM WARNING is issued when winter storm is occurring or is about to occur in the area, usually within 24 hours. Generally, a Winter Storm Warning is issued if at least 4-6 or more inches of snow or 3 or more inches of snow with a large accumulation of ice is forecast.