Tropical Cyclone Bulbul Moving Toward Kolkata

Tropical Cyclone Bulbul moved toward Kolkata, India on Friday.  At 4:00 p.m. EDT on Friday the center of Tropical Cyclone Bulbul was located at latitude 19.7°N and longitude 87.8°E which put it about 225 miles (360 km) south of Kolkata, India.  Bulbul was moving toward the north at 8 m.p.h. (13 k/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 861 mb.

It appeared that Tropical Cyclone Bulbul may have pulled drier air from India around the southern and eastern sides of its circulation.  Rainbands in those parts of the tropical cyclone consisted primarily of showers and lower clouds.  Microwave satellite images provided some evidence of an eye at the center of circulation.  A ring of thunderstorms around the eye exhibited weaker sections on the eastern side of the eye.  The strongest winds were occurring in the ring of storms.  Other strong bands of thunderstorms were present in the western half of the circulation.

Winds to hurricane/typhoon force extended out 35 miles (55 km) from the center of Tropical Cyclone Bulbul.  Winds to tropical storm force extended out 140 miles (220 km) from the center.  The Hurricane Intensity Index (HII) for Tropical Cyclone Bulbul was 16.5.  The Hurricane Size index (HSI) was 13.2 and the Hurricane Wind Intensity Size Index (HWISI) was 29.7.  Bulbul was capable of causing serious damage.

Tropical Cyclone Bulbul may be near its maximum intensity.  Bulbul will move over water where the Sea Surface Temperature is near 29°C.  So, there is sufficient energy in the upper Bay of Bengal to support further intensification.  However, the introduction of drier air into the southern and eastern parts of the circulation will inhibit the development of thunderstorms in those portions of the tropical cyclone.  Bulbul will move under the western end of an upper level ridge over southeast Asia.  The ridge will produce some vertical wind shear which will also inhibit further intensification.  Tropical Cyclone Bulbul could weaken when it nears the coast around the northern Bay of Bengal.

Tropical Cyclone Bulbul will move around the western end of the ridge over southeast Asia.  The ridge will steer Bulbul toward the north for another 18 to 24 hours.  On its anticipated track Tropical Cyclone Bulbul could approach the coast of India south of Kolkata in about 18 hours.  Bulbul will turn more toward the east when it moves around the northwestern part of the ridge in a day or so.

Tropical Cyclone Bulbul could be the equivalent of a hurricane/typhoon when it makes landfall in West Bengal south of Kolkata.  Bulbul will bring gusty winds to the coast of West Bengal and Bangladesh.  Tropical Cyclone Bulbul will be capable of generating a storm surge of up to 6 to 9 feet ( 2 to 3 meters) along portions of the coast around the northern Bay of Bengal.  That area is particularly prone to storm surges.  Bulbul will drop locally heavy rain over parts of West Bengal and Bangladesh when it moves inland.  Locally heavy rain could cause flash floods in some locations.