Typhoon Cempaka Strengthens Southwest of Iwo To, Forecast to Peak Monday

A typhoon is strengthening over open ocean south of Japan. Typhoon Cempaka — designated 31W by the U.S. Joint Typhoon Warning Center (JTWC) and Typhoon 2632 by the Japan Meteorological Agency (JMA) — was centred about 301 nautical miles west-southwest of Iwo To on Sunday, November 8, tracking west-northwest at 9 knots, according to JTWC Warning Nr 010, issued at 15:00 UTC.

At the warning's 12:00 UTC position fix, near 22.4°N 136.5°E, Cempaka's maximum sustained winds were 65 knots with gusts to 80 knots, its minimum central pressure was 989 millibars, and maximum significant wave heights around the storm reached 28 feet. The National Weather Service in Guam, relaying the same system in its Advisory Number 9 at 7:00 p.m. ChST on Sunday (09:00 UTC), put the centre near 22.2°N 136.9°E, about 330 miles west-southwest of Iwo To, with maximum sustained winds increased to 80 miles per hour.

Cempaka is one of three tropical cyclones active worldwide on Sunday, and the strongest of them — but every current forecast keeps it over water for its entire life.

Stronger before it weakens. JTWC forecasts Cempaka to reach 80 knots with gusts to 100 knots by 00:00 UTC on Monday, November 9, and to peak at 90 knots with gusts to 110 knots by 12:00 UTC on Monday. The National Weather Service in Guam likewise forecasts the typhoon to intensify through Monday, potentially reaching Category 2 strength early on Monday morning, with typhoon-force winds extending up to 30 miles from the centre.

The JMA's Sunday bulletin, issued at 12:00 UTC with the storm at 970 hectopascals and maximum winds of 70 knots near the centre, independently forecasts a peak of 85 knots by 12:00 UTC on Monday. The agencies measure and round differently, but they agree on the shape of the next two days: a Monday peak, then a weakening trend.

No landfall is forecast. JTWC's warning names no landfall, and no coastal watches or warnings are in effect for the storm. Cempaka is expected to slow tonight, becoming quasi-stationary at times on Monday as a mid-latitude trough breaks down the ridge steering it, and then turn gradually toward the east-northeast — away from land in every direction.

The Philippines is the nearest large landmass to the west, and its weather bureau, PAGASA, is monitoring the storm from outside the Philippine Area of Responsibility. In its Tropical Cyclone Advisory No. 2 at 11:00 a.m. on Sunday, PAGASA placed Cempaka about 1,720 kilometres east of extreme northern Luzon with winds of 110 kilometres per hour and gusts to 135, forecast it to enter the Philippine Area of Responsibility between Sunday evening and early Monday morning — where it would take the local name Samuel — and stated it is expected to remain over the Philippine Sea and not directly affect the country.

The turn begins on Monday. After its Monday peak near 24.0°N 135.5°E, JTWC forecasts Cempaka moving east-northeast and weakening steadily: 85 knots early on Tuesday, 70 knots by Tuesday afternoon, 55 knots on Wednesday and 45 knots by Wednesday afternoon, dissipating as a significant tropical cyclone over water by about November 12.

The JMA's extended outlook tells the same story on a slower clock, carrying the system east-northeast across the sea south of Japan and down to 40 knots by November 13. Mariners are the storm's main audience in the meantime: seas near the centre were already running at up to 28 feet on Sunday, and the JMA's high-seas forecast warned of 9-metre seas with heavy swell in the sea south of Japan.

WorldEye's hurricane tracker follows active tropical cyclones on the live globe, and the weather radar layer shows the precipitation around a system like Cempaka as it moves — the two views that matter for an open-ocean storm with no coastline in its path.

For the official word, JTWC issues new warnings every six hours, the National Weather Service in Guam relays advisories for the western Pacific, and the JMA is the official warning authority for Japanese waters. The next JTWC warning was scheduled for 21:00 UTC on Sunday.