Tag Archives: 91B

Tropical Cyclone Forming over Bay of Bengal

A tropical cyclone was forming over the Bay of Bengal on Tuesday morning. At 11:00 a.m. EDT on Tuesday the center of a low pressure system was located at latitude 8.3°N and longitude 88.3°E which put it about 370 miles (595 km) southwest of Port Blair. The low pressure system was moving toward the northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 998 mb.

A low pressure system was strengthening over the southern Bay of Bengal on Tuesday morning. The India Meteorological Department classified the system as a well marked low pressure system and the Joint Typhoon Warning Center designated the system as Invest 91B. The circulation around the low pressure system exhibited more organization on Tuesday morning. Several bands of showers and thunderstorms were beginning to revolve around the center of circulation. The strongest bands were in the southern and western parts of the low pressure system. Storms near the center of circulation began to generate upper level divergence that pumped mass away from the low pressure system. The removal of mass was causing the surface pressure to decrease.

The low pressure system will move through an environment favorable for intensification during the next few days. The low pressure system will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the center of an upper level ridge over the Bay of Bengal. The upper level winds are weak near the center of the ridge and there will be little vertical wind shear. The low pressure system will intensify during the next 48 hours. It is likely to strengthen to a tropical cyclone during the next 24 hours. The low pressure system is likely to intensify to the equivalent of a hurricane/typhoon later this week.

The low pressure system will move around the western end of a high pressure system that extends from the Western North Pacific Ocean to Southeast Asia. The high pressure system will steer the low pressure system toward the north during the next 24 hours. On its anticipated track the center of circulation will pass west of the Andaman Islands and the Nicobar Islands. Bands of showers and thunderstorms in the eastern side of the circulation will bring gusty winds and locally heavy rain to the Andaman Islands and the Nicobar Islands. The low pressure system will move toward the north-northeast later this week. It is likely to make landfall near the border between Bangladesh and Myanmar in a few days. The low pressure system is likely to be the equivalent of a hurricane/typhoon when it makes landfall.

Tropical Depression Forms Near Southern Tip of Sri Lanka

A tropical depression formed near the southern tip of Sri Lanka on Wednesday.  At 7:00 a.m. EST on Wednesday the center of Tropical Depression 96S was located at latitude 6.2°N and longitude 80.0°E which put it about 20 miles (30 km) northwest of Galle, Sri Lanka.  It was moving toward the west-southwest at 4 m.p.h.  The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h).  The minimum surface pressure was 1004 mb.

A center of circulation formed within a cluster of thunderstorms also designated as Invest 91B and the Indian Meteorological Department classified the system as a Depression.  The circulation in the tropical depression was still organizing.  A large, primary rainband wrapped around the southern and western sides of the center of circulation.  Additional bands of showers and strong thunderstorms were forming in the western half of the circulation.  Bands of showers and isolated thunderstorms were developing in the eastern half of the circulation.  Thunderstorms in the primary rainband were generating upper level divergence which was pumping away mass to the west of the depression.

The depression will move through an environment favorable for intensification during the next several days.  It will move over water where the Sea Surface Temperature is near 29°C.  An upper level ridge over India is generating easterly winds which are blowing toward the top of the circulation.  Those winds are causing moderate vertical wind shear which is probably the reason why most of the stronger thunderstorms are occurring in the western half of the depression.  The vertical wind shear will inhibit intensification, but it is not likely to prevent strengthening.  The depression is likely to intensify into a stronger tropical cyclone during the next several days.

The ridge over India is steering the tropical depression toward the west-southwest.  The ridge is forecast to steer the depression in a generally westerly direction during the next several days.  On its anticipated track the depression will move away from Sri Lanka and the center will pass south of India.  The depression could cause locally heavy rain and flash floods in parts of Sri Lanka and southern India.