Typhoon Sinlaku was bearing down on the Marianas on Monday morning.  At 11:00 a.m. EDT on Monday the center of Typhoon Sinlaku was located at latitude 13.3°N and longitude 147.2°E which put the center about 190 miles (335 km) east of Guam.  Sinlaku was moving toward the northwest at 8 m.p.h. (13 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 903 mb.

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

Tropical Storm Warnings are in effect for Guam, Pagan, and Alamagan.

A Typhoon Watch is in effect for Guam.

A Tropical Storm Watch is in effect for Agrihan.

Typhoon Sinlaku was maintaining its intensity as it was bearing down on the Mariana’s on Monday morning.  Sinlaku was the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  A circular eye with a diameter of 17 miles (28 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 in the upper levels of the atmosphere was nearly equal to the convergence of mass in the lower levels.  So, the surface pressure was nearly constant.

The circulation around Typhoon Sinlaku was large.  Winds to typhoon force extended out 80 miles (130 km) from the center of Sinlaku’s circulation.  Winds to tropical storm force extended out 290 miles (465 km) from the center of Typhoon Sinlaku.

The Hurricane Intensity Index (HII) for Typhoon Sinlaku is 40.4.  The Hurricane Size Index (HSI) is 28.4 and the Hurricane Wind Intensity Size Index (HWISI) is 68.8.  Typhoon Sinlaku is similar in intensity to Hurricane Maria when Maria was at its peak strength in 2017.  Sinlaku is bigger than Maria was.

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 28°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, the center of Typhoon Sinlaku will be near Tinian and Saipan in less than 24 hours.

Typhoon Sinlaku could be the equivalent of a Category 5 hurricane when it reaches Tinian and Saipan.  Sinlaku will be capable of causing catastrophic damage in Tinian and Saipan.  Typhoon Sinlaku will bring also strong winds and locally heavy rain to Guam, Rota, Pagan, and Alamagan. 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.