Tag Archives: Alamagan

Typhoon Jebi Hits Northern Marianas

Typhoon Jebi hit the Northern Mariana Islands on Thursday.  At 11:00 a.m. EDT on Thursday the center of Typhoon Jebi was located at latitude 17.8°N and longitude 146.2°E which put it about 35 miles (55 km) east-southeast of Pagan.  Jebi was moving toward the west at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 125 m.p.h. (205 km/h) and there were wind gusts to 155 m.p.h. (230 km/h).  The minimum surface pressure was 940 mb.  A Typhoon Warning was in effect for Agrihan, Pagan and Alamagan.

Typhoon Jebi was very well organized.  There was a small eye at the center of circulation.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Typhoon Jebi.  Storms near the core were generating strong upper level divergence which was pumping mass away from the typhoon.

Winds to typhoon force extended out about 50 miles (80 km) from the center of circulation.  Winds to tropical storm force extended out about 185 miles (295 km) from the center.  The Hurricane Intensity Index (HII) for Typhoon Jebi was 23.6.  The Hurricane Size Index (HSI) was 19.4 and the Hurricane Wind Intensity Size Index (HWISI) was 43.0.  Those indices indicate that Typhoon Jebi was capable of causing major damage.

Typhoon Jebi will be moving through an environment favorable for intensification during the next day or so.  Jebi will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there is little vertical wind shear.  Typhoon Jebi is forecast to intensify during the next 24 hours.  If an outer rainband wraps around the existing eye and eyewall, then an eyewall replacement cycle could cause the typhoon to weaken at least temporarily.

Typhoon Jebi will move around the western end of a subtropical ridge over the Western North Pacific Ocean.  Jebi will make a gradual turn toward the north during the next few days while it moves around the end of the ridge.  On its anticipated track Typhoon Jebi will move slowly away from the Northern Marianas.  Weather conditions should slowly improve when Jebi moves away.  The center of Jebi is forecast to pass south of Iwo To.  Typhoon Jebi could approach Honshu in four or five days.

Typhoon Jebi Intensifies Rapidly East of Northern Marianas

Typhoon Jebi intensified rapidly east of the Northern Marianas on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Typhoon Jebi was located at latitude 17.5°N and longitude 149.8°E which put it about 270 miles (435 km) east of Pagan.  Jebi was moving toward the west at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 105 m.p.h. (170 km/h) and there were wind gusts to 125 m.p.h. (205 km/h).  The minimum surface pressure was 959 mb.  A Typhoon Warning was in effect for Agrihan, Pagan and Alamagan in the Northern Marianas.

The circulation of Typhoon Jebi was very well organized and it was symmetrical.  A small circular eye formed at the center of circulation.  A ring of strong thunderstorms surrounded the eye and the strongest winds were occurring in that ring of storms.  Several bands of thunderstorms were revolving around the core of Typhoon Jebi.  Storms around the core were generating strong upper level divergence which was pumping large quantities of mass away from the typhoon.  Winds to typhoon force extended out about 25 miles (40 km) from the center of circulation.  Winds to tropical storm force extended out about 100 miles (160 km) from the center.

Typhoon Jebi will be moving through an environment very favorable for further intensification.  Jebi will move over water where the Sea Surface Temperature is near 29°C.  It will move through a region where the upper level winds are weak and there will be little vertical wind shear.  Jebi is likely to intensify into the equivalent of a major hurricane on Thursday.

Typhoon Jebi will move south of a subtropical ridge over the Western North Pacific for several more days.  The ridge will steer Jebi in a general westerly direction during that time.  Typhoon Jebi will reach the western end of the ridge in about 48 hours.  Jebi will make a gradual turn toward the north when it reaches the end of the ridge.  On its anticipated track Typhoon Jebi will reach the northernmost Mariana Islands within 24 hours.  Jebi will be capable of causing major damage when it arrives.  Jebi is forecast to pass south of Iwo To, but it will turn toward the major islands of Japan during the weekend.