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RSMC Tokyo-Typhoon Center

Notes on RSMC Tropical Cyclone Information

     Tropical cyclone information includes analyses and forecasts of tropical cyclones. It is provided by the RSMC (Regional Specialized Meteorological Center) Tokyo - Typhoon Center operated by JMA within the framework of the World Weather Watch (WWW) Programme of the World Meteorological Organization (WMO). It is primarily issued for National Meteorological Services in Asia and the western North Pacific region to assist them in issuing accurate tropical cyclone forecasting and timely warnings.
  • Thresholds of issuance
    Tropical cyclone information is issued when:
    -  a tropical cyclone of tropical storm (TS*) intensity or higher exists in the Center's area of responsibility;
    -  a tropical cyclone is expected to reach TS intensity or higher in the area within 24 hours;
    -  a tropical cyclone of TS intensity or higher is expected to move into the area within 24 hours.
    *  A TS is defined as a tropical cyclone with a maximum sustained wind speed of 34 knots or more and less than 48 knots.
  • Issuance times and forecast periods
    Information is issued every three hours.
    -  Advisories at 0000, 0600, 1200 and 1800 UTC contain 24-hour, 48-hour, 72-hour, 96-hour** and 120-hour** storm forecasts.
    -  Advisories at 0300, 0900, 1500 and 2100 UTC contain 24-hour, 45-hour*** and 69-hour*** forecasts.
    **  96-hour and 120-hour forecasts are issued in the advisories only in the case that a tropical cyclone is expected to hold TS intensity or higher in the next 72 hours.
    ***  45-hour and 69-hour forecasts are the same as the 48-hour and 72-hour forecasts in the advisories issued 3 hours before.
  • Contents
    Points of analysis:
    -  Center position of tropical cyclone
    -  Accuracy of center position determination
    -  Direction and speed of movement
    -  Central pressure
    -  Maximum sustained wind speed (10-minute average)
    -  Maximum wind gust speed
    -  Radii of wind areas over 50 and 30 knots
    24-, 48- (45-) and 72- (69-) hour forecasts:
    -  Center position and radius of probability circle****
    -  Direction and speed of movement
    -  Central pressure
    -  Maximum sustained wind speed (10-minute average)
    -  Maximum wind gust speed
    96- and 120- hour forecasts:
    -  Center position and radius of probability circle****
    -  Direction and speed of movement
    ****  A circular range into which a tropical cyclone is expected to move with a probability of 70% at each valid time.