Typhoon In-Fa battered Agrihan, Pagan, and Alamagan in the Northern Marianas early on Friday. At 5:00 a.m. EDT on Friday the center of Typhoon In-Fa was located at latitude 19.1°N and longitude 145.6°E which put the center about 35 miles (55 km) east of Agrihan. In-Fa was moving toward the northwest at 20 m.p.h. (32 km/h). The maximum sustained wind speed was 145 m.p.h. (235 km/h) and there were wind gusts to 175 m.p.h. (285 km/h). The minimum surface pressure was 943 mb.
Typhoon In-Fa continued to be in a relatively steady state on Thursday. A circular eye with a diameter of 40 miles (65 km) was at the center of In-Fa’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 In-Fa. Storms near the center of In-Fa generated upper level divergence that pumped mass away from the typhoon. The removal of mass in the upper levels was nearly equal to the convergence of mass in the lower levels of the atmosphere. So, the surface pressure did not change much on Thursday.
The size of the circulation around Typhoon In-Fa increased on Thursday. Winds to typhoon force extended out 80 miles (130 km) from the center of In-Fa’s circulation. Winds to tropical storm force extended out 175 miles (285 km) from the center of Typhoon In-Fa.
The Hurricane Intensity Index (HII) for Typhoon In-Fa is 29.9. The Hurricane Size Index (HSI) is 24.5 and the Hurricane Wind Intensity Size Index (HWISI) is 54.4. Typhoon In-Fa is similar in size and intensity to Hurricane Helen when Helene hit Florida in 2024.
Typhoon In-Fa will move through an environment that will be favorable for a strong typhoon during the next 24 hours. In-Fa will move over water where the Sea Surface Temperatures are near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon In-Fa appears to be in a near equilibrium with its environment. In-Fa is likely to maintain its intensity during the next 24 hours.
Typhoon In-Fa will move around the southwestern part of a high pressure system that is over the Western North Pacific Ocean. The high pressure system will steer In-Fa toward the northwest during the next 24 hours. On its anticipated track, Typhoon In-Fa will move away from Alamagan, Pagan, and Agrihan on Friday.
Typhoon In-Fa will continue to bring strong winds and heavy rain to Agrihan, Pagan, and Alamagan until it moves farther to the northwest. Heavy rain is likely to cause flash floods in some locations.