National Weather Service [1]
To keep an eye on weather warnings in near real time, check the interactive national weather map put out by the National Oceanic and Atmospheric Administration's National Weather Service [2] (NWS).
Warnings are color-coded by type of alert. Simply click on your area of interest to see details. Or search for a forecast by state, city/state or zip code.
The NWS site offers Active Alerts, Forecast Maps, and Radar, as well as information on Rivers, Lakes, Rainfall; Air Quality; Satellite; and Past Weather.