How does doppler radar work?

Watch this 18 hour Doppler radar composite animation courtesy of the COD GOES site. This animation shows the shower and t-storm clusters which traversed the Chicago area from roughly 3am CDT Sunday morning through just past 9am CDT this (Monday) morning. | Tom Skilling

Here's AN updated (at 3:05 pm CDT Friday) DOPPLER RADAR ANIMATION from the National Weather Service in Romeoville. The radar animation shows a narrow line of "training" t-storms exploding to life Friday morning and early afternoon--then sinking southward and reorganizing into a bow-shaped line of t-storms which made their way into northwest Indiana. Thunderstorms are said to "train" when they repeatedly fire over a confined area, producing extreme rainfall in the process. Repetitive and slow mov

DOPPLER RADAR ANIMATION covering the repetitive t-storms which "trained" over the Milwaukee area overnight. This radar animation runs 5 pm CDT Saturday evening through 8:55 am CDT this (Sunday) morning and is courtesy of the COD GOES Satellite and radar site. | Tom Skilling