11.3.2 autoMateD local evaluation in real ti M e (alert) Real-time rain-gauge and stream-gauge data provide the foundation of metropolitan flood warning systems. The NWS (1997) has described automated local flood warning systems (LFWS). A popu- lar LWFS known as ALERT (Automated Local Evaluation in Real Time) was originally developed by the National Weather Service in Sacramento, California. ALERT gauges transmit via wireless radio signals to a base station located at the agency headquarters (and other similar base stations). Through this system, real-time rainfall and stream stages are monitored remotely for an entire metro region. In addition to real-time data, the base station software also archives all data so that