Nationwide, the regular broadcasts are specifically tailored to weather information needs of the people within the service area of the transmitter. For example, in addition to general weather information, stations in coastal areas provide information of interest to mariners and those in agricultural areas provide information of interest to farmers. Other specialized information, such as hydrological forecasts and climatological data may be broadcast.
Weather messages are repeated every four to six minutes and are routinely updated every one to three hours, or more frequently in rapidly changing weather conditions.
During severe weather, National Weather Service forecasters can interrupt the routine weather broadcasts and insert special warning messages concerning imminent threats to life and property. The forecaster can also add special signals to warnings that trigger "alerting" features of specially equipped receivers. These radios are designed exclusively to receive NOAA Weather broadcasts. In the simplest case, this signal activates audible or visual alarms, indicating that an emergency condition exists within the broadcast areas of the station being monitored and alters the listener to turn up the volume and stay tuned for details.
Radios that receive only NOAA Weather Radio broadcasts, both with and without special alerting features, are available from several manufacturers. There are models that are small and portable and can go with you anywhere.
The National Weather Service has improved its service with a new generation of weather radio receivers, using NWS-developed technology, that permits listeners to screen out weather alarms that do not apply to them. This new generation of NWR receiver has a Specific Area Message Encoding (SAME) feature that allows consumers to choose only the official NWS watches and warnings they want. Older NOAA Weather Radios continue to work, but the older receivers do not allow listeners to screen out weather service alarms for individual counties.
NOAA Weather Radio coverage is limited to an area within 40 miles of the transmitter. The quality of the signal is determined by the distance from the transmitter, local terrain, and the location and sensitivity of the receiver. In general, people on flat land or at sea, using a high-quality receiver, can obtain reliable reception beyond 40 miles. Those living in cities surrounded by large buildings or in hilly areas may experience poor reception at considerably less than 40 miles.
Philadelphia region/Southern New Jersey NOAA Weather Radio frequencies: