Typhoon Maria Rapidly Intensifies to Equivalent of Cat. 5 Hurricane

Typhoon Maria rapidly intensified into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale on Thursday night.  At 11:00 p.m. EDT on Thursday the center of Typhoon Maria was located at latitude 16.2°N and longitude 141.9°E which put it about 250 miles (405 km) northwest of Guam.  Maria was moving toward the northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 160 m.p.h. (260 km/h) and there were wind gusts to 195 m.p.h. (315 km/h).  The minimum surface pressure was 918 mb.

Typhoon Maria continued to intensify rapidly on Thursday night and it reached the equivalent of Category 5 on the Saffir-Simpson Scale.  Maria is a strong, well organized typhoon.  There is a small circular eye at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds were occurring that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Maria.  Storms in the core were generating strong upper level divergence which was pumping large amounts of mass away from the typhoon.  The rapid removal of mass allowed the surface pressure to decrease quickly and the wind speeds to increase rapidly.

Winds to typhoon/hurricane force extended out about 45 miles (75 km) from the center of circulation.  Winds to tropical storm force extended out about 155 miles (250 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Maria was 43.5.  The Hurricane Size Index (HSI) was 17.8 and the Hurricane Wind  Intensity Size Index (HWISI) was 51.3.

Typhoon Maria will move through an environment favorable for strong tropical cyclones for another day or two.  Maria will move over water where the Sea Surface Temperature is near 30°C.  It will move through an area where the upper level winds are weak and there will be little vertical wind shear.  Typhoon Maria could intensify further on Friday.  However, a rainband could wrap around the existing eye and eyewall.  If that occurs, then an eyewall replacement cycle will begin.  Maria would weaken while the inner eyewall dissipates.  The typhoon could strengthen again if the outer eyewall contracts around the center of circulation.

Typhoon Maria was moving south of a subtropical ridge which was steering Maria toward the northwest.  The northwesterly motion is expected to continue for another 24 to 48 hours.  After that time the ridge is forecast to strengthen and steer Maria more toward the west-northwest.  on its anticipated track Typhoon Maria could approach Okinawa and the Ryukyu Islands in about four days.  Maris is likely to be a powerful typhoon at that time.