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Annual Tropical Cyclone Report 2017

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Executive Summary

The Annual Tropical Cyclone Report (ATCR) is prepared by the staff of the Joint Typhoon Warning Center (JTWC), a jointly manned United States Navy / Air Force organization under the operational command of the Commanding Officer, JTWC.

The original JTWC was established on 1 May 1959 when the Joint Chiefs of Staff directed Commander-in- Chief, US 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, Pacific Fleet (PACFLT). A subsequent USCINCPAC directive further tasked Commander, Pacific Air Force (PACAF) to provide for tropical cyclone (TC) reconnaissance support to the JTWC.

This edition of the ATCR documents the 2017 TC season and details operationally or meteorologically significant cyclones noted within the JTWC area of responsibility which encompasses the western North Pacific Ocean, the North Indian Ocean, and the Southern Hemisphere Pacific and Indian Oceans. Details are provided to describe either significant challenges and/or shortfalls in the TC warning system and to serve as a focal point for future research and development efforts. Also included are TC reconnaissance statistics and a summary of TC research as well as tactics, techniques and procedure (TTP) development that members of the JTWC conducted.

The central Pacific Ocean sea-surface temperatures continued to cool after the 2015 strong El Nino and the neutral conditions seen in 2016 transitioned into a weak La Nina. The net result was a further shift of the western North Pacific primary TC formation region westward. The total number of TCs in the western North Pacific reached 33, two above the 25-year mean, but there were an above-average number of tropical depressions and tropical storms and a below-average number of typhoons and super typhoons. Okinawa was impacted by one cyclone, mainland Japan was impacted by five cyclones, and Guam and South Korea were not impacted this season. The north Indian Ocean experienced normal activity of four cyclones, all in the Bay of Bengal, with one that moved into the Arabian Sea.

Southern Hemisphere activity continued to be well below the long term average of 28, with only 19 cyclones. However, TC activity returned to the area around Australia, with four making landfall. The remainder of the Southern Hemisphere activity was equally spread between the South Indian and Pacific Oceans.

Meteorological satellite data remained critical to the TC reconnaissance mission of the JTWC. Satellite analysts administratively assigned to the 17th Operational Weather Squadron, exploited a wide variety of electro-optic (EO), infrared (IR) and microwave satellite data to produce 6,913 position and intensity estimates (fixes), down from 8,274 in 2016. The USAF Mark IVB was the primary platform used by satellite analysts. The USN FMQ-17 satellite direct readout system was unavailable due to a system upgrade delay; the upgrade completion that occurred in mid-2018 allows for the direct read-out ingest of Japan Meteorological Agency (JMA) Himawari 8 (and eventually 9). Geo-located microwave and scatterometer imagery overlays available via the Automated Tropical Cyclone Forecast (ATCF) system from Fleet Numerical Meteorology and Oceanography Center (FNMOC) and Naval Research Laboratory, Monterey (NRL-MRY) were also used by JTWC to make TC fixes and to help determine TC structure and wind fields. METEOSAT-8, which the European Space Agency moved to 41.5o E longitude, was the primary geostationary satellite used in the Indian Ocean, although its positioning creates a gap in geostationary coverage east of the Bay of Bengal to East Java.

The USAF Weather Satellite Follow-on (WSF) program moved slowly forward, with vendor selection for the microwave instance (WSF-M) and USAF Weather leadership discussion with the National Oceanic and Atmospheric Administration (NOAA) about possible options including moving an older GOES geostationary satellite, designated WSF-G, over the Indian Ocean. DMSP F-19, the most recently launched USAF legacy polar orbiting satellite, had a command and control communications failure, resulting in a rapidly decaying orbit, rendering the satellite unusable. JTWC began evaluating scatterometer data from the Indian Space Research Organization (ISRO) ScatSat-1 satellite and data from NASA’s Soil Moisture Active Passive (SMAP). Scientists at the Jet Propulsion Lab (JPL) discovered they could also derive “extreme winds data” over oceanic areas with the data collected by the SMAP sensor. JTWC also continued to monitor the progress of various “Cube Sat” and “Micro Sat” research projects, including Cyclone Global Navigation Satellite System (CYGNSS) and the Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS).

JTWC continued to collaborate with TC forecast support and research organizations such as the FNMOC, NRLMRY, the Naval Post Graduate School, the Office of Naval Research (ONR), the 557 Weather Wing, and NOAA Line Offices for continued development of TC reconnaissance tools, numerical models and forecast aids. The U.S. Navy collaboration with NOAA, contracted with Raytheon, for the Advanced Weather Interactive Processing System continued to move forward, with installation at JTWC expected in May 2018 and network authority to operate in 2019.

Behind all these efforts are the dedicated team of men and women, military and civilian at JTWC. Special thanks to the entire JTWC Information Services Department for their continued outstanding information technology support and the Support Services, Training and Strategy and Requirements Departments for working tirelessly to ensure JTWC had the necessary training and 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 TC research; the NOAA National Environmental Satellite, Data, and Information Service for satellite reconnaissance support; Jim Vermuelen, Yiping Wang, Richard Bankert, Josh Cossuth, Mark DeMaria, John Knaff, and Chris Velden for their continuing efforts to exploit remote sensing technologies in new and innovative ways; as well as Charles R. “Buck” Sampson and Mike Frost for their outstanding support and continued development of the ATCF system.