The Annual Tropical Cyclone Report (ATCR) is prepared by the staff of the Joint Typhoon Warning Center (JTWC), a jointly manned United States Air Force/Navy organization formally under the operational command of the Commanding Officer, Naval Maritime Forecast Center/Joint Typhoon Warning Center (NMFC/JTWC), Pearl Harbor, Hawaii. During 2011, the Navy Meteorological and Oceanographic (METOC) community reorganization resulted in the stand down of NMFC and a transfer of the Optimal Track Ship Routing (OTSR) and ship weather forecasts (WEAX) missions to Fleet Weather Center, San Diego. This shift in mission, and subsequent Navy Command name change, resulted in JTWC being a stand-alone Navy Command primarily focused on tropical cyclones.
The original JTWC was established on 1 May 1959 when the Joint Chiefs of Staff directed Commander in Chief, U.S. Pacific Command (USCINCPAC) to provide a single tropical cyclone warning center for the western North Pacific region. USCINCPAC delegated the tropical cyclone forecast and warning mission to Commander in Chief, U.S. Pacific Fleet. A subsequent USCINCPAC directive further tasked Commander in Chief, Pacific Air Force to provide for tropical cyclone (TC) reconnaissance support to the JTWC. Currently, JTWC operations are guided by USPACOM Instruction 0539.1 and Pacific Air Forces Instruction 15-101.
This edition of the ATCR documents the TC season and details operationally or meteorologically significant cyclones noted within the JTWC Area of Responsibility. Details are provided to describe operational impacts from tropical cyclones as well as significant challenges and/or shortfalls in the TC warning system. These details are provided to serve as input for future research and development efforts.
Below average tropical cyclone activity continued in the western North Pacific Ocean, continuing a trend that started in 2005, with only 27 TCs observed compared to the long term average of 31. Unlike the previous year, there were four cyclones that reached super typhoon intensity. The TC formation region was displaced north and west again in 2011, a characteristic common during La Nina conditions. Several of these early to mid-season forming TCs exhibited ―S‖ shaped, looping, or generally erratic tracks, with numerous passages near or over Okinawa. In fact, Super Typhoon Songda (04W) passed just west of Kadena Air Base and destroyed the WSR-88D Doppler Weather Radar. As of the writing of this report, the 18 Air Wing at Kadena AB had procured the funding necessary to replace the radar.
The Southern Hemisphere activity also continued a below normal trend, with 21 cyclones observed compared to the long term average of 28 and the Northern Indian Ocean experienced near normal activity with 6 cyclones. Most of the TCs in the Northern Indian Ocean were weak, except TC 06B (Thane), which peaked in intensity just prior to making landfall in southern India at 90 knots.
Weather satellite data remained the mainstay of the TC reconnaissance mission to support the JTWC. Satellite analysts exploited a wide variety of conventional and microwave satellite data to produce 11,339 position and intensity estimates (fixes), primarily using the USAF Mark IVB and the USN FMQ-17 satellite direct readout systems. Geo-located microwave satellite imagery overlays available via the Automated Tropical Cyclone Forecast (ATCF) system from Fleet Numerical Meteorology and Oceanography Center and the Naval Research Lab Monterey to make TC fixes continued to be an invaluable source of information on TC location and intensity. Satellite Operations (SATOPS) continued to advocate for improved satellite reconnaissance capability, including continuation of the Navy Research Labs Coriolis/WindSAT, an ocean surface vector wind capable 43 channel microwave sensor on the Defense Weather Satellite System (DWSS), and exploitation of international remote sensing capabilities, including the Indian Space Research Organizations OceanSAT-2 and the joint Meteo France / Indian Mega Tropiques. Unfortunately, budget cuts within the United States Government resulted in cancellation of DWSS program, so Air Force leadership decided to reduce its Defense Meteorological Satellite Program (DMSP) support from 2 orbits to 1 in order to extend the life of the legacy DMSP satellites.
JTWC continued to collaborate with TC forecast support and research organizations such as the Fleet Numerical Meteorology and Oceanography Center (FNMOC), Naval Research Laboratory, Monterey (NRLMRY), Naval Post Graduate School, the Office of Naval Research, and Air Force Weather Agency (AFWA) for continued development of numerical TC models and forecast aids. This included evaluation of AFWA’s 4 kilometer Weather and Research Forecast (WRF), Mesoscale Ensemble Prediction System (MEPS), and NRLs Coupled Ocean/Atmosphere Mesoscale Prediction System – Tropical Cyclone (COAMPS-TC). Additionally, operational support and enhancements to the ATCF system continued, making development and issuance of tropical cyclone warnings as streamlined as possible for forecasters.
The Techniques Development (TECHDEV) continued their herculean efforts to develop techniques or transition mature research into operations to help improve TC reconnaissance and forecasting. A repeatable TC formation potential process was developed by TECHDEV, tested and implemented in 2011. This checklist will be presented at the 2012 AMS Conference on Hurricanes and Tropical Meteorology. Additionally, TECHDEV acquired a USPACOM sponsored Intern from the University of Hawaii to work on TC genesis and other projects directly related to or supporting operations.
Behind all these efforts are the dedicated team of men and women, military and civilian at JTWC. Special thanks to the entire N6 Department for their outstanding IT support and the administrative and budget staff who worked tirelessly to ensure JTWC had the necessary resources to get the mission done.
A Special thanks also to: FNMOC for their operational data and modeling support; the NRLMRY and ONR for its dedicated research; the National Oceanic and Atmospheric Administration National Environmental Satellite, Data, and Information Service for satellite support; for their high quality support; all the men and women of the ships and facilities ashore throughout the JTWC area of responsibility; Dr. John Knaff, Mr. Jeff Hawkins, Dr. Mark DeMaria, and Mr. Chris Velden for their continuing efforts to exploit remote sensing technologies in new and innovative ways; Mr. Charles R. ―Buck‖ Sampson, Ms. Ann Schrader, Mr. Mike Frost, and Mr. Chris Sisko for their outstanding support and continued development of the ATCF system.