Typhoon Trami Intensifies in Equivalent of Category 5 Hurricane

Typhoon Trami intensified on Monday into the equivalent of a Category 5 hurricane on the Saffir-Simpson Scale.  At 5:00 p.m. EDT on Monday the center of Typhoon Trami was located at latitude 19.7°N and longitude 129.0°E which put it about 485 miles (780 km) south of Okinawa.  Trami was moving toward the west-northwest at 7 m.p.h. (11 km/h).  The maximum sustained wind sped 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 912 mb.

Typhoon Trami went through an eyewall replacement cycle on Sunday, which temporarily interrupted its intensification.  When the inner eyewall dissipated on Monday, then Typhoon Trami resumed intensifying.  The eyewall replacement cycle caused Trami’s circulation to get larger.  There is now a large circular eye with a diameter of 40 miles (65 km) at the center of circulation.  The eye is surrounded by a ring of strong thunderstorms and the strongest winds are occurring in that ring of storms.  Several bands of showers and thunderstorms are revolving around the core of Typhoon Trami.  Storms around the core are generating large amounts of upper level divergence which is pumping mass away from the typhoon in all directions.

Typhoon Trami has a large symmetrical circulation.  Winds to typhoon force extend out about 70 miles (110 km) from the center of circulation.  Winds to tropical storm force extend out about 235 miles (380 km) from the center of circulation.  The Hurricane Intensity Index (HII) for Typhoon Trami is 35.0.  The Hurricane Size Index (HSI) is 25.3 and the Hurricane Wind Intensity Size Index (HWISI) is 60.3.

Typhoon Trami will move through an environment very favorable for intense typhoons during the next 12 to 24 hours.  Trami 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 Trami has been through one eyewall replacement cycle.  If another rainband wraps around the existing eye and eyewall and another eyewall replacement cycle starts, then weakening could occur.  An upper level trough near the east coast of China will move north of Typhoon Trami.  Westerly winds at the southern end of the trough could affect the northern portion of Trami’s circulation.  If wind shear increases later this week, then Typhoon Trami will weaken.

Typhoon Trami will move south of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Trami in a west-northwesterly direction during the next 12 to 24 hours.  The upper level trough will weaken the ridge and Trami could turn more toward the north in a day or so.  The winds steering Typhoon Trami could weaken during the middle of the week and it could move slowly toward the north for a day or two.  On its anticipated track Typhoon Trami could approach the southern Rykyu Islands in three or four days.  Trami could still be a powerful typhoon at that time.