WSR-74 RADAR

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

s were Weather Surveillance Radars designed in 1974 for the National Weather Service

National Weather Service

The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...

. They were added to the existing network of the WSR-57

WSR-57

WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:...

 model to improve forecasts and severe weather warnings. Some have been sold to other countries like Australia, Greece, and Pakistan.

Radar properties

There are two types in the WSR-74 series, which are almost identical except for operating frequency. The WSR-74C (used for local warnings) operates in the C band

C band

The C band is a name given to certain portions of the electromagnetic spectrum, including wavelengths of microwaves that are used for long-distance radio telecommunications. The IEEE C-band - and its slight variations - contains frequency ranges that are used for many satellite communications...

, and the WSR-74S (used in the national network) operates in the S band

S band

The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...

 (like the WSR-57 and the current WSR-88D). S band frequencies are better suited because they are not attenuated significantly in heavy rain while the C Band is strongly attenuated.

The WSR-74C uses a wavelength of 5.4 cm. It also has a dish diameter of 8 feet, and a maximum range of 579 km (313 nm) as it was used only for reflectivities

Reflectivity

In optics and photometry, reflectivity is the fraction of incident radiation reflected by a surface. In general it must be treated as a directional property that is a function of the reflected direction, the incident direction, and the incident wavelength...

 (see Doppler dilemma).

History

The WSR-57 network was very spread out, with 66 radars to cover the entire country. There was little to no overlap in case one of these vacuum-tube radars went down for maintenance. The WSR-74 was introduced as a "gap filler", as well as an updated radar that, among other things, was transistor-based.

WSR-74C radars were generally local-use radars that didn't operate unless severe weather was expected, while WSR-74S radars were generally used to replace WSR-57 radars in the national weather surveillance network. When a network radar went down, a nearby local radar might have to supply updates like a network radar. Corpus Christi became the first operational site for the WSR-74C on February 1, 1976.

128 of the WSR-57 and WSR-74 model radars were spread across the country as the National Weather Service's radar network until the 1990s. They were gradually replaced by the WSR-88D model (Weather Surveillance Radar - 1988, Doppler), constituting the NEXRAD

NEXRAD

NEXRAD or Nexrad is a network of 159 high-resolution Doppler weather radars operated by the National Weather Service, an agency of the National Oceanic and Atmospheric Administration within the United States Department of Commerce...

 network. The WSR-74 had served the NWS for two decades.

Thirteen WSR-74Cs still have not been decommissioned and, of those, eight remain in active use today. No WSR-74Ss are in the NWS inventory today, having been replaced by the WSR-88D. Some of these radars are in commercial use.

Radar sites in the US

WSR-74 sites include the following two categories:

WSR-74C Site	Commissioned	Decommissioned
Abilene, TX (ABI)	August 27, 1977	April 30, 1997
Akron, OH (CAK)	June 1, 1977	November 15, 1995
Albany, NY (ALB)	July 27, 1977	November 2, 1995
Alpena, MI (APN)	June 8, 1977	December 9, 1996
Atlanta, GA (ATL) On a building between Hartsfield and downtown to this day.	October 20, 1976	February 1, 1996
Augusta, GA (AGS)	July 1, 1976	July 30, 1996
Austin, TX (AUS)	April 9, 1976	October 13, 1995
Baton Rouge, LA (BTR)	October 20, 1978	May 14, 1996
Beckley, WV (BKW)	November 1, 1977	January 12, 1996
Billings, MT (BIL)]	April 18, 1978	May 30, 1996
Bismarck, ND (BIS)	October 5, 1978	February 28, 1996
Burlington, VT (BTV)	Late 1977	January 29, 1998
Charlotte, NC (CLT)	February 28, 1978	September 17, 1996
Chattanooga, TN (CHA)		June 10, 1998
Cheyenne, WY (CYS)	September 15, 1976	April 24, 1996
Cleveland, OH (CLE)	August 4, 1976 Replaced a WSR-3.	November 15, 1995
Columbia, MO (COU)	Novbember 9, 1977 Replaced a WSR-3.	June 19, 1996
Columbia, SC (CAE)	January 26, 1976 JReplaced a WSR-1.	October 25, 1995
Columbus, GA (CSG)	April 2, 1979	April 3, 1996
Columbus, OH (CMH)	June 9, 1977 Replaced a WSR-3.	December 1, 1995
Concordia, KS (CNK)	February 18, 1977 Replaced a WSR-3.	November 9, 1995
Corpus Christi, TX (CRP)	February 1, 1976	March 10, 1997
Duluth, MN (DLH)	1977	March 25, 1997
Erie, PA (ERI)	August 30, 1977	January 15, 2000?
Fort Smith, AR (FSM)	November 25, 1975 Replaced a WSR-3.	July 7, 1998
Fort Wayne, IN (FWA)	March 12, 1976 Replaced a WSR-3.	July 8, 1998
Goodland, KS (GLD)	June 6, 1978 Replaced a WSR-3.	October 25, 1995
Harrisburg, PA (HAR)	June 28, 1977	January 12, 1996
Hartford, CT (BDL)	April 1977	November 2, 1995
Houghton Lake, MI (HTL)		December 9, 1996
Huntsville, AL (HSV) (Doppler capability after July 1991)	1977. Replaced a WSR-3.	December 15, 1999? Now the ARMOR radar.
Indianapolis, IN (IND)	September 28, 1977	February 28, 1996
Las Vegas, NV (LAS)		September 1, 1995
Los Angeles, CA (LAX) On top of the Federal Building in Westwood to this day.		May 15, 1995
Louisville, KY (SDF)		July 19, 1994
Lubbock, TX (LBB)		April 3, 1996
Macon, GA (MCN)	April 18, 1977	April 3, 1996
Madison, WI (MSN) At Madison Airport.	1972	May 7, 1996
Marquette, MI (MQT)		July 16, 1996
Meridian, MS (MEI)	November 2, 1976	December 26, 1996
Mobile, AL (MOB)		October 12, 1995
Moline, IL (MLI)	August 30, 1977	January 19, 1996
Montgomery, AL (MGM) (Doppler capability after 1982)	1977	June 4, 1996
Muskegon, MI (MKG)	March 25, 1976	August 13, 1996
Norfolk, NE (OFK)	May 14, 1976	March 25, 1997
North Platte, NE (LBF)		November 27, 1996
Omaha, NE (OVN)	1977	July 10, 1996
Paducah, KY (PAH) At the Paducah Airport.	1984	February 23, 1996
Phoenix, AZ (PHX)		August 15, 1994
Portland, OR (PDX)		January 30, 1996
Raleigh, NC (RDU)	May 19, 1977	December 22, 1995
Rapid City, SD (RAP)		November 4, 1996
Rochester, MN (RST)	April 1976	January 9, 1997
San Angelo, TX (SJT)	October 1977	April 22, 1997
Savannah, GA (SAV)	November 15, 1982	February 11, 1997
Shreveport, LA (SHV)		June 5, 1996
Sioux Falls, SD (FSD)	1976	October 4, 1996
South Bend, IN (SBN)	October 22, 1982	July 8, 1998
Springfield, IL (SPI)	October 16, 1980	July 30, 1996
Topeka, KS (TOP)	1976	November 2, 1995
Tucson, AZ (TUS)	January 1983	March 14, 1996
Tulsa, OK (TUL)	March 12, 1976	April 5, 1995
Tupelo, MS (TUP)	April 1, 1983	December 6, 1995
Waco, TX (ACT)	November 8, 1976	September 13, 1995
Waterloo, IA (ALO)	November 19, 1976	January 17, 1997
Wichita Falls, TX (SPS)	February 5, 1977	December 26, 1996
Williston, ND (ISN)	February 21, 1978	Not decommissioned
Worcester, MA (ORH)	July 2, 1976	April 5, 1995

WSR-74S Site	Commissioned	Decommissioned
Alliance, NE (AIA)	June 10, 1977	January 17, 1997
Binghamton, NY (BGM)	March 8, 1978	September 26, 1995
Charleston, WV (CRW) WSR-74S providing local coverage	May 16, 1977	January 12, 1996
Chatham, MA (CHH)	May 6, 1983	April 5, 1995
Detroit, MI (DTW)	March 9, 1984 Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:... .	November 9, 1995
Fargo, ND (FAR)	February 1, 1978 Was a WSR-74C from Oct. 9, 1976 to Nov. 27, 1977	November 27, 1996
Jackson, KY (JKL) WSR-74S providing local coverage	April 1, 1981	July 1, 1997
Key West, FL (EYW)	1980. Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:... .	October 20, 1998
Longview, TX (GGG)	March 1, 1978	March 14, 1996
Marseilles, IL (MMO) (Doppler capability)	November 1, 1974. Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:...  at Chicago.	January 19, 1996
Memphis, TN (MEG) At East Memphis/Agricenter site	January 1986. Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:... .	June 21, 1995
Monett, MO (UMN)	March 16, 1971 Replaced a WSR-57	February 1, 1996
Patuxent River, MD (NHK) At Patuxent River NAS	Early 1980s. Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:...  at Washington, DC.	November 17, 1995
Portland, ME (PWM)	March 5, 1985 Replaced a WSR-57 WSR-57 WSR-57 radars were the USA's main weather surveillance radar for over 35 years. The National Weather Service operated a network of this model radar across the country, watching for severe weather.-History:... .	September 13, 1995
San Juan, Puerto Rico (SJU) WSR-74S providing local coverage		February 26, 1999
Volens, VA (VQN)	April 12, 1977	December 1, 1995
West Palm Beach, FL (PBI) WSR-74S providing local coverage		October 13, 1995