The steep horizontal gradients of sea-level pressure imply strong surface winds (Section 12.2 Note 13.F). In fact, TCs [tropical cyclone] are conventionally distinguished from tropical storms by wind speeds above 25 m/s for at least ten minutes (Table 13.2). A rough rule is that a central pressure of 950 hPa means winds up to 39 m/s at 30ºS, 46 m/s at 20ºS and 56 m/s at 10ºS (Note 13.F).