Tropical Cyclone Vince Intensifies to Equivalent of a Major Hurricane

Tropical Cyclone Vince intensified to the equivalent of a major hurricane over the South Indian Ocean southwest of the Cocos Islands during Monday night.  At 4:00 a.m. EST on Tuesday the center of Tropical Cyclone Vince was located at latitude 18.6°S and longitude 89.6°E which put the center about 595 miles (960 km) southwest of the Cocos Islands.  Vince was moving toward the southwest at 12 m.p.h. (19 km/h).  The maximum sustained wind speed was 115 m.p.h. (185 km/h) and there were wind gusts to 145 m.p.h. (235 km/h).  The minimum surface pressure was 958 mb.

Tropical Cyclone Vince intensified to the equivalent of a major hurricane during Monday night.  Vince appeared to go through an eyewall replacement cycle after it intensified.  The inner end of a rainband wrapped around the original small eye at the center of Vince’s circulation.  The small eye dissipated and a larger outer eye formed.

The circulation around Tropical Cyclone Vince weakened after the eyewalll replacement cycle.  A ring of thunderstorms surrounded the new larger eye.  The strongest winds were occurring in that ring of storms.  The distribution of thunderstorms around Tropical Cyclone Vince was asymmetrical.  Most of the thunderstorms were occurring in bands in the western side of Vince’s circulation.  Bands in the eastern side of Tropical Cyclone Vince consisted primarily of showers and lower clouds.  Storms near the center of Vince generated upper level divergence that pumped mass away to the west of the tropical cyclone.

The eyewall replacement cycle caused the size of the circulation around Tropical Cyclone Vince to increase.  Winds to hurricane/typhoon force extended out 50 miles (80 km) from the center of Vince’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) from the center of Tropical Cyclone Vince.

The Hurricane Intensity Index (HII) for Tropical Cyclone Vince was 20.6.  The Hurricane Size Index (HSI) was 13.7 and the Hurricane Wind Intensity Size Index (HWISI) was 34.3.  Tropical Cyclone Vince was similar in size and intensity to Hurricane Delta when Delta hit Southwest Louisiana in 2020.

Tropical Cyclone Vince will move through an environment favorable for intensification during the next 24 hours.  Vince will move over water where where the Sea Surface Temperatures are near 28°C.  It will move under the northern part of an upper level ridge over the South Indian Ocean.  The upper level ridge will produce easterly winds that will blow toward the top of Vince’s circulation.  Those winds will cause moderate vertical wind shear.  Even though Tropical Cyclone Vince will move through an environment favorable for intensification during the next 24 hours, Vince is likely to weaken due to the effects of the eyewall replacement cycle.

Tropical Cyclone Vince will move around the northern side of a high pressure system over the South Indian Ocean.  The high pressure system will steer Vince toward the west-southwest during the next 24 hours.  On its anticipated track Tropical Cyclone Vince will pass far to the south of Diego Garcia later this week.

Elsewhere, Tropical Cyclone Taliah intensified as it moved farther away from Western Australia.  At 4:00 a.m. EST on Tuesday the center of Tropical Cyclone Taliah was located at latitude 15.6°S and longitude 110.4°E which put the center about 515 miles (830 km) north-northwest of Exmouth, Australia.  Taliah was moving toward the west at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 972 mb.

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