Typhoon Sinlaku intensified to the equivalent of a category 5 hurricane on the Saffir-Simpson Scale on Sunday.  At 11:00 a.m. EDT on Sunday the center of Typhoon Sinlaku was located at latitude 11.4°N and longitude 149.9°E which put the center about 410 miles (660 km) east-southeast of Guam.  Sinlaku was moving toward the north-northwest at 11 m.p.h. (17 km/h).  The maximum sustained wind speed was 175 m.p.h. (285 km/h) and there were wind gusts to 205 m.p.h. (335 km/h).  The minimum surface pressure was 902 mb.

Typhoon Warnings were in effect for Rota, Tinian, and Saipan.

A Tropical Storm Warning was in effect for Guam.

A Typhoon Watch was also in effect for Guam.

Typhoon Sinlaku rapidly intensified to the equivalent of a Category 5 hurricane on Sunday.  A circular eye with a diameter of 20 miles (32 km) was as the center of Sinlaku’s circulation.  The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms.  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 caused the surface pressure to decrease.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 60 miles (95 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 275 miles (445 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 40.4.  The Hurricane Size Index (HSI) is 21.3 and the Hurricane Wind Intensity Size Index (HWISI) is 61.7.  Typhoon Sinlaku is similar in size and intensity to Hurricane Maria when Maria was at its peak strength in 2017.

Typhoon Sinlaku will move through an environment favorable for a very powerful typhoon during the next 24 hours.  Sinlaku will move over water where the Sea Surface Temperatures are near 29°C.  It will move under the middle of an upper level ridge that is over the Western North Pacific Ocean.  The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear.  Typhoon Sinlaku is likely to maintain its intensity during the next 24 hours unless an eyewall replacement cycle occurs.  Sinlaku could weaken if the inner end of a rainband wraps around the existing eye and eyewall.  If concentric eyewalls form, then an eyewall replacement cycle would cause Typhoon Sinlaku to weaken.

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 northwest during the next 24 hours.  On its anticipated track, Typhoon Sinlaku will approach the Marianas in less than 35 hours.

Typhoon Sinlaku will be the equivalent of a major hurricane when it approaches the Marianas.  Sinlaku will bring very strong winds and locally heavy rain to Guam, Rota, Tinian, and Saipan.   Heavy rain is likely to cause flash floods in some locations.

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

Typhoon Sinlaku could also cause a storm surge of up to 17 feet (5.1 meters) along parts of the coasts of the Marianas.