The National Weather Service issues a variety of severe weather warnings, watches, advisories, and statements. These warnings, watches, etc. may be issued for a single forecast zone (usually one county or a part of a county) or for many forecast zones. The events are indicated on the map by different colors. Only one event per forecast zone can be shown on the map at a time, a forecast zone may have several warnings and watches in effect but only the most crucial one is displayed on the map.