One of the most important things you and your family need to know before severe weather strikes is the difference between a watch and a warning.
A watch means severe weather is possible in the coming hours.
A warning means severe weather is ongoing or is about to hit, you need to take action now.
The Storm Prediction Center in Norman, Oklahoma issues watches for the potential of severe weather in the coming hours. Watches are usually issued in advance of severe weather for a portion of a region. Watches usually last several hours.
A SEVERE THUNDERSTORM WATCH is issued when conditions are favorable for thunderstorms in and near the watch area to produce hail at least 1" in diameter and gusts of at least 58mph. A watch is issued when there is the potential for multiple severe storms across an area. At FOX 34 we use green to highlight severe thunderstorm watches on the weather crawl at the bottom of the TV screen and on radar maps.
A TORNADO WATCH is issued when conditions are favorable for thunderstorms to produce tornadoes, large hail and damaging wind. We use blue to highlight tornado watches.
In rare instances the SPC will issue a Particularly Dangerous Situation (PDS) Tornado Watch; This is when conditions are favorable for a dangerous tornado outbreak, including long-lived, destructive tornadoes. SPC may also issue a PDS severe thunderstorm watch when the tornado threat is low but there is a significant threat of widespread wind destruction.
Local offices of the National Weather Service issue SEVERE THUNDERSTORM WARNINGS for thunderstorms that produce hail of at least 1" diameter and/or gusts of at least 58mph. We use yellow to highlight severe thunderstorm warnings.
The Weather Service issues TORNADO WARNINGS for thunderstorms that are likely producing a tornado or about to produce one, based on ground reports from trained spotters or significant signatures on radar. When a tornado warning is issued for your area you need to get to your tornado safe place immediately. We use red to highlight tornado warnings.
Warnings are usually issued for a duration of less than an hour, specific to parts of a county or counties affected by the storm. The Weather Service uses polygons to outline the threat area, rather than issuing for an entire county.