Joint Typhoon Warning Center

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Joint Typhoon Warning Center
Agency overview
Formed May 1, 1959; 56 years ago (1959-05-01)
Headquarters Pearl Harbor, Hawaii
Employees 37 (2013)[1]
Agency executive Robert Falvey, Director
Parent agency United States Navy
United States Air Force

The Joint Typhoon Warning Center (JTWC) is a joint United States NavyUnited States Air Force task force located in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North West Pacific Ocean, South Pacific Ocean and Indian Ocean for United States Department of Defense interests, as well as U.S. and Micronesian civilian interests within the command's area of responsibility (AOR). The JTWC provides support to all branches of the U.S. Department of Defense and other U.S. government agencies. Their products are intended for the protection of primarily military ships and aircraft as well as military installations jointly operated with other countries around the world.[2]


Radar image of Typhoon Cobra

The beginning of the formation of a typhoon warning center in the Pacific occurred in the wake of Typhoon Cobra on December 18, 1944. A small but significant typhoon east of the Philippines, Typhoon Cobra led to the largest naval disaster in United States history with 790 lives lost, and was the worst United States military loss from a tropical cyclone impact since 1889. Due to this typhoon, weather stations were established in Caroline Islands, and eventually in Manila, Iwo Jima, and Okinawa. New weather central offices (for coordinating data) were established at Guam and Leyte.[3] JTWC was originally established in 1959 at Nimitz Hill, Guam combined the efforts of the former naval centers located in Guam, Hawaii, and the Philippines with the Air Force center in Japan.[4] In November 1962, Typhoon Karen destroyed the building housing the Fleet Weather Center/Joint Typhoon Warning Center. It relocated in a more typhoon-proof building in 1965.[5] It was relocated to Pearl Harbor on January 1, 1999 due to the 1995 Base Realignment and Closure Commission round.

Standards and practices[edit]

A more modernized method for forecasting tropical cyclones had become apparent by the 1980s. Prior to the development of ATCF, the tools used by the Department of Defense to forecast tropical cyclone track were acetate. grease pencils, and disparate computer programs.[6] The ATCF software was developed by the Naval Research Laboratory for the JTWC beginning in 1986,[7] and used since 1988. It was adapted for use at the National Hurricane Center (NHC) in 1990.[6]

JTWC adheres to the World Meteorological Organization's (WMO) rules for storm names and adheres to acknowledged guidelines for intensity of tropical cyclones and tropical storms, with the exception of using the U.S. standard of measuring sustained winds for 1-min instead of the 10-min span recommended by the WMO (see Saffir-Simpson Hurricane Scale). The JTWC is not one of the WMO designated Regional Specialized Meteorological Centres, nor one of its Tropical cyclone warning centres, as its main mission is to support the United States government agencies.[8] JTWC monitors, analyzes, and forecasts tropical cyclone formation, development, and movement year round.[9] Its area of responsibility covers 89% of the world's tropical cyclone activity.[10]


The Center is manned by about 37 U.S. Air Force and Navy personnel.[1] The JTWC uses several satellite systems and sensors, radar, surface and upper level synoptic data as well as atmospheric models to complete its mission.[2]

See also[edit]


  1. ^ a b Annual Tropical Cyclone Report 2013 (PDF) (Report). Pearl Harbor, Hawaii: Joint Typhoon Warning Center. 2014. p. 5. 
  2. ^ a b Joint Typhoon Warning Center. "Joint Typhoon Warning Center Mission Statement". Retrieved July 17, 2013. 
  3. ^ Naval Historical Center. Typhoons and Hurricanes: Pacific Typhoon, 18 December 1944. Retrieved on 2006-12-10.
  4. ^ Richard Anstett. Post World War II Era. Retrieved on 2006-12-10.
  5. ^ Richard Anstett. JTWC Formation, 1958-1959. Retrieved on 2006-12-10.
  6. ^ a b Ronald J. Miller, Ann J. Schrader, Charles R. Sampson, and Ted L. Tsui (December 1990). "The Automated Tropical Cyclone Forecasting System (ATCF)". Weather and Forecasting (American Meteorological Society) 5: 653–600. doi:10.1175/1520-0434%281990%29005<0653%3ATATCFS>2.0.CO%3B2. 
  7. ^ Charles R. Sampson and Ann J. Schrader (June 2000). "The Automated Tropical Cyclone Forecasting System (Version 3.2)". Bulletin of the American Meteorological Society (American Meteorological Society) 81 (6): 1231–1240. doi:10.1175/1520-0477(2000)081<1231:tatcfs>;2. 
  8. ^ Joint Typhoon Warning Center Prodcut Notice at bottom of webpage. "Joint Typhoon Warning Center". Retrieved July 17, 2015. 
  9. ^ Joint Typhoon Warning Center. "Joint Typhoon Warning Center Frequently Asked Questions". Retrieved July 17, 2013. 
  10. ^ Freeman, Bob (November 13, 2009). "Joint Typhoon Warning Center Marks 50 Years of Service". U.S. Department of Defense. Retrieved July 17, 2013. 

External links[edit]