Typhoon Champi, which the Japan Meteorological Agency numbers as Typhoon No. 30, reached a central pressure of 900 hPa with maximum sustained winds of 115 knots (215 km/h) in an agency observation reported on Oct. 21. Forecast tracks then carried the storm west-northwest toward waters east of Taiwan and Japan’s Sakishima Islands, the southern end of the Ryukyu chain, with the closest approach expected on Oct. 23 and 24. Every figure after the Oct. 21 observation is a forecast.
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The agency classified the storm as large and violent at that point. It reported gusts of up to 165 knots (305 km/h), a westward-northwestward motion of 14 knots, and a position about 835 kilometers south of Miyakojima and 820 kilometers east of northern Luzon. Gale-force winds of 30 knots or more reached about 650 kilometers northeast of the center and 500 kilometers southwest, and storm-force winds of 50 knots or more reached about 240 kilometers northeast and 185 kilometers southwest.
The 900 hPa reading in JMA’s bulletin
The 900 hPa figure comes from a Weathernews marine-forecast page that reproduces the Japan Meteorological Agency’s Oct. 21 observation, timed at 03:45 UTC. A second Weathernews report, published on Oct. 21 and citing the same agency, gives the same 900 hPa pressure and 115-knot sustained winds from a bulletin issued at 09:45 JST, with the position at 18.1 degrees north and 130.2 degrees east at 09:00 JST. Two separate write-ups of the agency’s bulletin agree on both numbers, which makes 900 hPa the lowest central pressure in the records read for this article. The word peak therefore describes the bulletins reviewed, and the same agency’s forecast had the pressure rising afterward, to 905 to 915 hPa on Oct. 22 and about 950 hPa on Oct. 23.
Wind strength was the other measure of how intense the typhoon became. The agency’s 115-knot figure is a sustained wind, and it is not the only wind number in circulation: a Khaleej Times report from Oct. 21 carried a peak of 296 km/h attributed to Taiwan’s Central Weather Administration and called Champi the most powerful storm so far this year.
The Sakishima Islands and Taiwan on Oct. 23 and 24
The Weathernews marine page says the track heads west-northwest across the Philippine Sea, passing near eastern Taiwan and the southern Ryukyu Islands, known as the Sakishima Islands, through about Oct. 24, with gusts near 100 knots as the system closes in. The other Weathernews report is a day earlier on timing. It forecasts the typhoon to pass near the Sakishima Islands as a very strong typhoon from late afternoon to early evening on Oct. 23, with heavy rain, violent winds and high waves highly likely around the islands. The two timings differ by about a day, and both place the closest approach on Oct. 23 or 24.
For Taiwan the outcome hinged on track. The Weathernews report said impacts depended on whether the storm shifted north or south, and it cited Taiwan’s Central Weather Administration giving a 72 percent probability of gale-force winds in Keelung City within 120 hours. The Khaleej Times report said earlier models that had shown a landfall at Eluanbi, Taiwan’s southern tip, on Friday had been replaced by a forecast that Champi would turn sharply north over cooler waters off the east coast and spare the island a direct hit. It still expected extremely heavy rain island-wide until Saturday, Oct. 24, and waves of up to six meters off the east coast.
Kyushu and the weakening forecast
The Weathernews marine page projects steady weakening as the typhoon recurves across the East China Sea toward western Japan by Oct. 26. Its intensity forecast has sustained winds near 85 knots on Oct. 23, a severe tropical storm of about 55 knots on Oct. 25 and a tropical storm of about 35 knots on Oct. 26 as it accelerates toward the Tsushima Strait. The Weathernews report from Oct. 21 says the track increasingly points to a northeastward recurve across the East China Sea and a risk of landfall in the Kyushu region. The marine page also lists the shipping threat window as Oct. 21 to 25 and says the storm warning area was forecast to widen to about 500 kilometers east and 430 kilometers west of the center by Oct. 24, so vessels well away from the track still had reason to stay clear.
The Saffir-Simpson scale gives a rough measure of how strong a storm with a 296 km/h peak is. On the National Hurricane Center’s wind scale, Category 5 begins at 157 mph, or about 253 km/h, so a sustained wind of 296 km/h would be well above that line. The 215 km/h sustained wind in the Japanese agency’s own bulletin is a different averaging period and is not directly comparable.
Readers in the islands and on Kyushu should treat the track and intensity numbers as forecasts that change with each bulletin. The agency’s live typhoon map is the place where current warnings and positions are posted, and the Weathernews pages themselves note that track, intensity and wind forecasts may change and that the latest official updates should be monitored.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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