Each marker points along the aircraft’s track.
Radar frames are 5-minute national composites and run about 5–10 minutes behind real time, and cover the contiguous US only. Zone-based alerts have no polygon of their own and are drawn only when Zone shapes is on. Aircraft coverage depends on volunteer receivers, so a thin area means no receiver, not no traffic.
Not for life-safety decisions. Use official National Weather Service warnings at weather.gov, and your local emergency management, for any decision affecting safety or property.
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