Typhoon Sinlaku was still bringing wind and rain to the Northern Marianas on Thursday.  At 5:00 a.m. EDT on Thursday the center of Typhoon Sinlaku was located at latitude 18.0°N and longitude 144.6°E which put the center about 90 miles (145 km) west of Alamagan.   Sinlaku was moving toward the north at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 953 mb.

Typhoon Warnings remain in effect for Rota, Tinian, Saipan, Pagan, Alamagan, and Agrihan.

Typhoon Sinlaku was weakening gradually as it moved just to the west of the Northern Marianas.  The circulation around Sinlaku was pulling drier air into the typhoon.  There were fewer clouds in the regions between the rainbands.  Typhoon Sinlaku also appeared to be in the going through another eyewall replacement cycle.

The circulation around Typhoon Sinlaku was still well organized even though Sinlaku was weakening.  A circular eye with a diameter of 35 miles (55 km) was still visible at the center of Sinlaku’s circulation.  Bands of showers and thunderstorms were revolving around the center of Typhoon Sinlaku.  Storms near the center of Sinlaku generated upper level divergence that pumped mass away from the typhoon.  The removal of mass in the upper levels of the atmosphere was less than the convergence of mass in the lower levels.  So, the surface pressure was continuing to increase gradually.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 90 miles (145 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 290 miles (470 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 20.6.  The Hurricane Size Index (HSI) is 32.7 and the Hurricane Wind Intensity Size Index (HWISI) is 53.2.  Typhoon Sinlaku is similar in intensity to Hurricane Irma when Irma hit Southwest Florida in 2017.  Sinlaku is bigger than Irma was.

Typhoon Sinlaku will move around the western part of a high pressure system that is over the Western North Pacific Ocean.  The high pressure system will steer Sinlaku toward the north-northeast during the next 24 hours.  On its anticipated track, the center of Typhoon Sinlaku will move over the northernmost islands in the Northern Marianas during the nest 24 hours.  Sinlaku will start to move away from the Marianas on Friday.

Typhoon Sinlaku will move through an environment that will become more unfavorable for a strong typhoon during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 26°C.  It will move under the southeastern part of an upper level trough that is southeast of Japan.  The upper level trough will produce southwesterly winds that will blow toward the top of Sinlalu’s circulation.  Those winds will cause the vertical wind shear to increase.  Typhoon Sinlaku will also continue to pull drier air into its circulation.  The drier air will continue to to inhibit the development of new thunderstorms in the rainbands revolving around the center of Sinlaku’s circulation.  The cooler Sea Surface Temperatures, more vertical wind shear and drier air will cause Typhoon Sinlaku to continue to weaken during the next 24 hours.

Typhoon Sinlaku will continue to bring strong winds and heavy rain to the Northern Marianas during the next 24 hours.  Heavy rain is likely to cause flash floods in some locations.

Flood Watches remain in effect for Guam, Rota, Tinian, and Saipan.

Typhoon Sinlaku could also cause a storm surge of up to 10 feet (3 meters).