Severe weather glossary - wistv.com - Columbia, South Carolina

Severe weather glossary

General

Advisories — Advisories are issued when events are expected to remain below the warning criteria, but still cause significant inconvenience. Most common in association with snow events.

Watches — A watch tells you that conditions are favorable and there is a good chance that the event may happen. When a watch is issued begin making preparations for the upcoming event. Tune in to for more information. Watches are intended to heighten public awareness of the situation.

Warnings — A warning means that a certain weather event is IMMINENT. Measures should be taken to safeguard life and property IMMEDIATELY.

Warnings

Coastal Flood Warning — A Coastal Flood Warning is issued when moderate to severe coastal flooding is occurring or is imminent.

Flash Flood Warning — A Flash Flood Warning will be issued in response to a few hours of locally heavy rainfall, a dam or levee failure, or water released from an ice jam rapidly flooding nearby land.

Flood Warning — A Flood Warning will be issued when inundation of a normally dry area near a stream or other watercourse is expected, OR unusually severe ponding of water expected.

High Wind Warning — Issued for sustained wind speeds of 40 MPH or greater lasting for 1 hour or longer, OR winds of 58 MPH or greater for any duration of time.

River Flood Warning — A River Flood Warning is issued when river flooding is occurring or imminent at one or more forecast points along a river.

Severe Thunderstorm Warning — When a Severe Thunderstorm Warning is issued, tornadoes and/or severe thunderstorms are occurring and have been spotted or detected by radar. The National Weather Service (NWS) defines a severe thunderstorm as having winds 50 knots (58 mph) or hail greater than ¾" in diameter (about dime-sized). (A storm that spawns a tornado is obviously also considered severe.) There is imminent danger for people in the area warned. Issued by a local NWS office, the size of the warning area is generally the size of one or two counties and usually lasts less than an hour. Stay away from windows, doors and outside walls. Put as many walls between you and the tornado as possible on the lowest floor of your building. If you do not have a basement, seek shelter in an interior bathroom or closet. Get under something sturdy. Protect your head. Stay away from mobile homes. Get out of your vehicle. If there is no safe shelter, lie flat in the nearest ditch or ravine with your hands shielding your head.

Special Marine Warning — A Special Marine Warning is issued for a brief/sudden occurrence of sustained wind or frequent gusts > 34 knots, usually associated with thunderstorms.

Tornado Warning — When a Tornado Warning is issued, tornadoes are occurring and have been spotted or detected by radar. There is IMMINENT DANGER for people in the area warned. Issued by a local NWS office, the size of the warning area is generally the size of one or two counties and usually lasts less than an hour. Stay away from windows, doors and outside walls. Put as many walls between you and the tornado as possible on the lowest floor of your building. If you do not have a basement, seek shelter in an interior bathroom or closet. Get under something sturdy. Protect your head. Stay away from mobile homes. Get out of your vehicle. If there is no safe shelter, lie flat in the nearest ditch or ravine with your hands shielding your head.

Watches

Coastal Flood Watch — A Coastal Flood Watch is issued when moderate to severe coastal flooding is possible.

Flash Flood Watch — A Flash Flood Watch will be issued for serious situations in which life and/or property are in danger. Flash Flood watch covers flash flooding, widespread urban and small stream, and headwater flood events.

Flood Watch — A Flood Watch will be issued for situations related to widespread general flooding.

High Wind Watch — Issued when wind speeds are forecast to meet warning criteria with in the next 24-36 hours.

River Flood Watch — A River Flood Watch is issued when river flooding is possible at one or more forecast points along a river.

Severe Thunderstorm Watch — A Severe Thunderstorm Watch will be issued when conditions are favorable for development of severe thunderstorms. While not anticipated, tornadoes may occur in the watch area. The Storms Prediction Center (SPC) is the sole agency responsible for issuing a watch. A watch covers several thousands of square miles and generally lasts from two to six hours. Keep an eye on the sky for changing conditions and make preparations in case a weather warning is issued.

Tornado Watch — A Tornado Watch will be issued when conditions are favorable for the development of severe thunderstorms and tornadoes. The Storm Prediction Center (SPC) is the sole agency responsible for issuing a watch. A watch covers several thousands of square miles and generally lasts from two to six hours. Keep an eye on the sky for changing conditions and make preparations in case a weather warning is issued.

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