NEXRAD Now An Historical Look at NEXRAD Radar, also known as radio detection and rang- information for operational purposes. All of these ing, is one of the earlier technological develop- factors really helped to spur the growth of radar ments that had a huge impact on the field of meteorology as a science. meteorology. Weather Surveillance Radar-1988, After WWII, the NWS, formally known as the Doppler (WSR-88D) Next Generation Weather Weather Bureau, obtained various aircraft radars Radar (NEXRAD) has become a staple technology from the Navy. Most of them were AN/APS-2F for the National Weather Service (NWS) to meet radars which stood for Airborne Radar and they the needs of its mission in detecting severe atmo- were modified and put into operation around the spheric features such as tornadoes, hail, and snow U.S. at about 5 per year. These were then renamed squalls. This technology, first used by the military Weather Surveillance Radar (WSR) -1s, -1As, -3s, to detect the movement of objects such as planes and -4s. All of these radars were pretty much the and ships in WWII, is now used in real-time opera- same and differed by some controls and indicators. tions to detect the sorts of atmospheric phenomena The first WSR was installed at Washington, D.C. that could impact public safety and property. Here National Airport on March 12, 1947 and on June 1, we will discuss the historical family line of radars 1947 a second WSR was installed at a NWS office that eventually led to the development of NEXRAD in Wichita, Kansas. The radar in Wichita proved its used by the NWS today. worth when it was used to help guide and aircraft The British were actually the first to “develop threatened by severe weather into clear skies so it radio-location, direction-finding devices that could could land safely. locate thunderstorms” through the efforts of Sir WSR radars were all beginning to show their Robert A. Watson-Watt around 1935. Then, in the value in similar circumstances as what became U.S. from 1942-1944, the Massachusetts Institute known as the U.S. Basic Weather Radar Network of Technology’s (MIT) Radiation Laboratory (Rad began to form and expand after 1947. This network Lab) showed that weather could be detected on cer- consisted of the early WSR-series systems, air tain types of radars out to ranges of 150 miles and at force, civil government and cooperative radars. different wavelengths. Because of this, the Army Eventually radars were being developed specifi- Air Forces Weather Service established a program cally for meteorological use and one of the first was for the use of weather radar. Most U.S radar known as the AN/CPS-9 Storm Detection Radars, research and development was conducted at MIT’s produced by Raytheon Manufacturing Company. Rad Lab during WWII. In addition, because there The CPS-9’s were actually acquired by the Army were air traffic control and harbor defense radars set Continued on Page 32 up on the Atlantic and Pacific sides of Panama, sci- entists from the MIT Rad Lab were able to visit and determine the effects of the atmosphere and useful- ness of radar in observing atmospheric phenom- ena. The early use of this first radar network for weather detection and surveillance led to the recog- nition of many basic features of storm structure and organization and helped to realize the value of this page 31 NEXRAD Now History Continued from Page 31 Air Forces Weather Service and installed at military about noon. By 2pm on April 5, 1956, the Texas bases all over the world. Studies and research mod- A&M University radar began seeing hook-echoes els of the CPS-9 were also conducted by MIT Rad and University meteorologists were able to call the Lab, as well as by the Signal Laboratory. Bryan Police Department and the College Station As the NWS considered expanding their radar School District to let them know about the impend- network in the 1950s, a few major severe weather ing touchdown of tornadoes. The school district events occurred and lead to the formation of the decided to keep their students in school a bit longer Texas Tornado Warning Network and the establish- instead of releasing them at their normal dismissal ment of communications between the NWS offices and this probably saved numerous lives. As one of and local public officials. The NWS agreed to oper- the first known tornado warnings based solely on ate and maintain WSR-1, -1A, -3, or -4s at their radar detection, the value of this technology was offices and to provide warnings to the public when becoming more visible to society as a whole. confirmed sightings were made - establishing vol- Hurricanes became another driver for the instal- unteer spotter networks. Today, a more formal spot- lation of radars. Their design used a frequency ter program called SKYWARN® is run by the NWS known as S-band, which allowed for longer range where volunteers are trained to identify and describe and more power in detection. After some extensive severe local storms. Since the program formally hurricane-force wind damage and flooding from 5 started in the 1970s, the information provided by hurricanes in 2 years from 1954-1955, the NWS SKYWARN® spotters, coupled with Doppler radar developed a major budget proposal for Congress to technology, improved satellite and other data, has improve its warning services for hurricanes and enabled NWS to issue more timely and accurate severe weather, which was quickly approved. The warnings for tornadoes, severe thunderstorms and budget included funding for the design, procure- flash floods. ment, installation, and staffing for what became the In 1953, a tornadic feature known as a hook- WSR-57 radar. Raytheon Manufacturing Company shaped echo was first detected by a radar near was selected as the prime contractor; 31 radars were Champaign-Urbana, Illinois and a couple of months ordered by the NWS and installed at already exist- later, two additional recordings of these echoes were ing weather service offices beginning in 1959 in made in Waco, Texas and Worcester, Massachusetts. Miami, Florida and ending in the early 1960s. The installation of the WSR radars was a joint While the main purpose was to install these near effort between local, state and the federal govern- coastal areas, eleven of them were installed in the ment, as well as universities. A great example of Midwest to detect severe storms. Fourteen addi- the partnership between the weather service and the tional radars were purchased in the late 60s to local community expand the network east of the Rocky Mountains. It occurred on April 5, 1956 is also important to note that these newer installa- when a tornado watch tions were placed in locations where weather ser- was issued by a weather vice offices did not already exist. The main focus service office in Kansas was to space the radars out optimally for coverage City for a specific area and continuity with the already existing radars. around Bryan, Texas at Continued on Page 33 page 32 NEXRAD Now History Continued from Page 32 Some of the major design specifications process radar data and application software for their included an “improved ability to detect storms radars. Eventually more sophisticated algorithms behind intervening rainfall as to observe hurricanes and techniques were developed that were also at great distances.” In 1963 the NWS began to expanded to operational radars and it led to an standardize the performance of the WSR-57s improved knowledge base for the weather forecast- through calibration techniques. The WSR-57 also ers who had come to rely on radar data to do their had a near real-time telephone transmission line for daily jobs. Color monitor technology was also data and eventually a dial-in capability was added introduced, which made it even easier for meteorol- to allow access by military, airline offices and tele- ogists to be able to recognize storm echoes and vision stations, providing radar data remotely. other features. Remote access is still an important part of the radar During this same time, the MIT Rad Lab had network today. been looking at the use of the Doppler Effect to As discussed above, the NWS had installed measure target velocities by radar as a potential many conventional, non-Doppler weather radars measurement for wind speeds, but the development around the country but eventually they had to con- of pulse-Doppler technology for operational use sider the technology with which they should replace took a while. In 1971, the first Doppler radar was them due to the aging WSR -1s, -1As, -3s, and -4s. installed at the National Severe Storms Laboratory Spare parts were disappearing and the 1940s tech- (NSSL) in Norman, Oklahoma and in 1973 a sec- nology upon which they were designed was just no ond Doppler radar was installed at Cimarron Air- longer feasible. The Office of the Federal Coordi- port in Oklahoma – both were meant to study the nator for Meteorological Services and Supporting morphology of storms and used S-band frequency. Research began releasing a Federal Plan for By 1976, the Department of Commerce (DOC), Weather Radars and Remote Displays which was Department of Defense (DOD) and the Department used by Congress as a “single source for reviewing of Transportation (DOT) formed the tri-agency the overall Federal program in meteorological ser- Joint Doppler Operational Project (JDOP) to vices and supporting research.” The 1969 edition explore the benefits of Doppler radar observations. indicated that the NWS intended to buy more mod- Doppler radar was considered the next upgrade ern local-warning radars to replace the WSR -1s, - over conventional radar (i.e.