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    Oct 1, 2023 #hurricane, #typhoon, #weather


    Coastal Watches/Warnings and Forecast Cone for Storm Center

    cone graphic

    * If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

    Click Here for a 5-day Cone Printer Friendly Graphic

    How to use the cone graphic (video):

    Link to video describing cone graphic

    About this product:

    This graphic shows an approximate representation of coastal areas under a hurricane warning (red), hurricane watch (pink),
    tropical storm warning (blue) and tropical storm watch (yellow). The orange circle indicates the current position of the
    center of the tropical cyclone. The black line, when selected, and dots show the National Hurricane Center (NHC) forecast track of the center
    at the times indicated. The dot indicating the forecast center location will be black if the cyclone is forecast to be
    tropical and will be white with a black outline if the cyclone is forecast to be extratropical. If only an L is displayed,
    then the system is forecast to be a remnant low. The letter inside the dot indicates the NHC’s forecast intensity for that time:

    D: Tropical Depression – wind speed less than 39 MPH
    S: Tropical Storm – wind speed between 39 MPH and 73 MPH
    H: Hurricane – wind speed between 74 MPH and 110 MPH
    M: Major Hurricane – wind speed greater than 110 MPH

    NHC tropical cyclone forecast tracks can be in error. This forecast
    uncertainty is conveyed by the track forecast “cone”, the solid white
    and stippled white areas in the graphic. The solid white area depicts
    the track forecast uncertainty for days 1-3 of the forecast, while the
    stippled area depicts the uncertainty on days 4-5. Historical data
    indicate that the entire 5-day path of the center of the tropical
    cyclone will remain within the cone about 60-70% of the time. To
    form the cone, a set of imaginary circles are placed along the
    forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions,
    where the size of each circle is set so that it encloses 67% of the
    previous five years official forecast errors. The cone is then formed
    by smoothly connecting the area swept out by the set of circles.

    It is also important to realize that a tropical cyclone is not a point. Their
    effects can span many hundreds of miles from the center. The area
    experiencing hurricane force (one-minute average wind speeds of at least
    74 mph) and tropical storm force (one-minute average wind speeds of
    39-73 mph) winds can extend well beyond the white areas shown enclosing
    the most likely track area of the center. The distribution of hurricane
    and tropical storm force winds in this tropical cyclone can be seen in
    the Wind History graphic linked above.

    Considering the combined forecast uncertainties in track, intensity, and size, the
    chances that any particular location will experience winds of 34 kt (tropical storm force),
    50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in

    tabular form for selected locations and forecast positions
    . This information is also presented in
    graphical form for the 34 kt, 50 kt,
    and 64 kt thresholds.

    Note:  A detailed definition of the NHC track forecast cone is also available.

    By NHC