Tag Archives: Invest 90B

Tropical Cyclone Could Form East of Sri Lanka

A tropical cyclone could form over the Bay of Bengal east of Sri Lanka during the next 24 hours. A low pressure system over the southern Bay of Bengal was designated as Invest 90B on Monday. At 10:00 p.m. EST on Monday the center of the low pressure system was located at latitude 8.5°N and longitude 84.5°E which put it about 185 miles (300 km) east-northeast of Batticaloa, Sri Lanka. The low pressure system was moving toward the west at 8 m.p.h. (13 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 1004 mb.

The circulation around a low pressure system over the Bay of Bengal east of Sri Lanka strengthened on Monday. More thunderstorms formed near the center of the low pressure system and the inner end of a rainband wrapped partly around the center of circulation. More thunderstorms formed in bands revolving around the center. Storms near the center of circulation generated upper level divergence that pumped mass away to the west of the low pressure system.

The low pressure system will move through an environment favorable for the formation of a tropical cyclone during the next 24 hours. The low pressure system will move over over water where the Sea Surface Temperatures are near 27˚C. It will move under the western end of an upper level ridge centered over Southeast Asia. The ridge will produce southeasterly winds that will blow toward the top of the low pressure system. Those winds will cause vertical wind shear and the shear will inhibit somewhat the formation of a tropical cyclone. However, the wind shear may not be strong enough to prevent the low pressure system from strengthening into a tropical cyclone. Invest 90B could strengthen to a tropical cyclone during the next 24 hours.

The low pressure system will move south of a strong high pressure system over southern Asia. The high pressure system will steer the low pressure system toward the west-southwest. On its anticipated track the low pressure system could reach the east coast of Sri Lanka within 24 hours. The low pressure system will bring gusty winds and locally heavy rain to Sri Lanka. Heavy rain could cause flash floods in some locations.

Depression Forms over Bay of Bengal

A depression formed over the Bay of Bengal on Friday morning. At 10:00 a.m. EST on Friday the center of the depression was located at latitude 9.4°N and longitude 83.4°E which put it about 320 miles (515 km) southeast of Chennai India. It was moving toward the north-northwest at 7 m.p.h (11 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 1000 mb.

The circulation around a low pressure system over the Bay of Bengal strengthened on Friday morning and the system was classified as a depression by the India Meteorological Department. More thunderstorms develop near the enter of the depression. Bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away to the north of the depression.

The depression will move through an environment somewhat favorable for intensification during the next 24 hours. The depression will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the western part of an upper level ridge centered over southeast Asia. The ridge will produce southeast winds that will blow toward the top of the depression. Those winds will cause moderate vertical wind shear and the shear will inhibit intensification. The depression is likely to intensify during the next 24 hours unless the upper level winds get stronger.

The depression will move south of a high pressure system centered over southeast Asia. The high pressure system will steer the depression slowly toward the northwest during the next 24 hours. On its anticipated track the depression will remain northeast of Sri Lanka and it will move closer to southern India.

Tropical Depression Forms Over Bay of Bengal

A tropical depression formed over the Bay of Bengal on Wednesday.  At 10:00 a.m. EST on Wednesday the center of the tropical depression was located at latitude 16.2°N and longitude 83.3°E which put it about 105 miles (170 km) south of Visakhapatnam, India.  The depression was moving toward the north-northeast at 9 m.p.h. (15 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 1003 mb.

A low level center of circulation developed on the southwestern edge of a cluster of showers and thunderstorms over the Bay of Bengal and the Indian Meteorological Department classified the system as a depression.  The circulation is not particularly well organized.  As noted above, the low level center is on the southwestern side of showers and thunderstorms.  Several bands of showers and storms formed northeast of the center.  There were not many thunderstorms near the center of circulation.  There were bands of showers and lower clouds in the western half of the circulation.  An upper level trough over India is producing southwesterly winds which are blowing over the top of the depression.  Those winds are causing moderate vertical wind shear, which is tilting the upper part of the depression to the northeast of the low level center of circulation.  The depression also appears to be pulling drier air from India around the western side of the circulation.  The combination of wind shear and drier air is probably responsible for the asymmetrical distribution of thunderstorms.

The depression will move through an environment that is marginally favorable for intensification.  It will move over water there the Sea Surface Temperature is near 28.5°C.  So, there is enough energy in the upper ocean to support intensification.  However, the upper level trough over India will continue to cause moderate vertical wind shear, which will inhibit the consolidation of the low level circulation.  The depression is also likely to continue to draw in drier air from over India into the western part of the circulation.  The depression could strengthen, but it could also weaken if the upper level winds get stronger.

The trough over India is steering the depression slowly toward the north-northeast and that general motion is expected to continue.  On its anticipated track the depression is expected to move toward the northern Bay of Bengal during the next several days.  The depression could make landfall over northeastern India or Bangladesh later this week.

The primary risk from the depression will be locally heavy rain, which could cause flash floods in parts of eastern India and Bangladesh.  The wind will push water toward the north coast of the Bay of Bengal and the depression could cause a storm surge of several feet (approximately one meter).