Known as the Voice of NOAA's National Weather Service, NWR is provided as a public service by the NOAA. NWR includes more than 940 transmitters , covering all 50 U.S. states, adjacent coastal waters, Puerto Rico, the U.S. Virgin Islands, Guam, American Samoa and Saipan. NWR requires a special radio receiver or scanner capable of receiving the signal.
The radio service transmits weather warnings and forecasts 24 hours a day. In addition to weather information, NWR works in cooperation with the FCC Emergency Alert System, providing comprehensive weather and emergency information. In conjunction with federal, state, and local emergency managers and other public officials, NWR also broadcasts warning and post-event information for all types of hazards, including natural (such as earthquakes or avalanches), environmental (such as chemical releases or oil spills), and public safety (such as AMBER alerts or 911 Telephone outages).
Many television stations which broadcast in MTS stereo and have the capability (both commercial and public), will also air their local feed of NWR on their second audio program channel if they aren't carrying a program which features either a Spanish language translation or a Descriptive Video Service track for the visually impaired. Some digital subchannels which carry weather information may also have NWR airing in the background, while regular analog television stations carry the audio during times they are off-the-air and transmitting a test pattern, in lieu of a reference tone.
Most stations broadcast on a special VHF frequency band at 162 MHz, which has seven FM channels reserved to weather radio broadcasts. The original frequency was 162.550, with 162.400 and 162.475 being added later. In recent years, the proliferation of stations meant to make sure everyone has access to warnings has pushed that number to seven, now including the "intermediate" channels of 162.425, 162.450, 162.500, and 162.525 MHz. These channels (often numbered in that order) are receivable on special weather radio receivers, available by mail-order and at some retailers, on most marine VHF radio transceivers, Amateur radios, and on scanners. These "weather radios" are available for prices ranging from US$35 and up. In addition, many consumer electronics, such as two-way radios and CB radios, are now being sold with the ability to receive weather radio broadcasts.
As of late 2006, there are more than 900 NWS transmitters serving 95% of the United States population. There are two different channel numbering systems used by various weather radio manufacturers. The first is the chronological sequence that the radio frequencies were allocated to the service: 1=162.550, 2=162.400, 3=162.475, 4=162.425, 5=162.450, 6=162.500, 7=162.525. The second is in simple increasing radio frequency sequence: 1=162.400, 2=162.425, 3=162.450, 4=162.475, 5=162.500, 6=162.525, 7=162.550. In addition, it may be possible to receive weather broadcasts on more than one of the seven channels at a given location. The NWS suggests that users determine which frequency (as opposed to channel) is intended for their specific location so that they are assured of receiving correct information.
Alerting
When a weather warning is issued for the area which a station covers, certain weather radios are designed to turn on or sound an alarm upon detection of a 1050 Hz tone, issued for ten seconds immediately before the warning message. The specification calls for the NWS transmitter to send the 1050 Hz tone for 10 seconds, and the receiver to decode it within 5 seconds (any extra tone time over and above the decode time is considered as part of the alerting mechanism). This system simply turns on the audio of every muted receiver within the radio horizon of the transmitter (i.e. any receiver within the transmitters "footprint").
Newer radios can instead detect a digital-over-audio protocol called Specific Area Message Encoding or SAME, which allows the users to program their radios for specific geographical areas of interest and concern, rather than for an entire regional broadcast area. The SAME code is broadcast, followed by the 1050 Hz tone. The beauty of the SAME codes is that they eliminate the numerous "false alarms" for the 1050 Hz weather alerts that may apply to an area 100 or 150 miles (240 km) distant. The SAME codes are mostly aligned along county lines using the standard US Government FIPS county codes. Most modern SAME equipped radios can be programmed to receive alerts for more than one FIPS code if the user is located along a county boundary.
Once the SAME receivers are programmed they will limit alarms to only certain warnings, and only to the actual section of the broadcast area which the listener is located prior to the broadcast of the 1050 Hz tone. Some receivers allow you to program in several codes so you can include the areas surrounding your location. For example, if your area has frequent storm warnings, and the storms usually come from the east, you can program your receiver for the code for your area, plus the code for the area to the east. (This notification system was later adopted by the Emergency Alert System—the replacement for the earlier Emergency Broadcast System and even earlier CONELRAD) now required by the FCC for broadcast stations.
In September 2008, Walgreens announced that it would utilize the SAME/NOAA system to deliver local weather alerts via their system of LED billboards located outside of the drugstore chain's locations built or remodeled since 2000 to provide an additional avenue of weather information .
In Canada, stations officially implemented SAME in May 2007. Many Canadian stations also used to operate Weathercopy, which was a data stream that transmitted entire text forecasts and warnings, but was not designed for alerting. This system was decommissioned in 2003 because of new technologies such as the internet and satellite.
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