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91B (Northern Indian Ocean)
May 8, 2014

[image-78]NASA Sees System 91B Lingering over Southwestern India

The tropical low pressure area known as System 91B has been making a slow northerly crawl while sitting inland in southwestern India, and NASA's Terra satellite captured a visible image of the struggling storm that showed half of it is over the Northern Indian Ocean.

NASA's Terra satellite passed over System 91B over southwestern India and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image on May 8 at 05:40 UTC/1:40 a.m. EDT. The despite having a poorly defined low-level circulation center on infrared imagery, the circulation is visible in the MODIS image. The MODIS image shows that the eastern quadrant of the broad tropical low pressure system remains over southwestern India, while the western quadrant extends into the Northern Indian Ocean. The thunderstorms are fragmented in the low pressure area.

The Joint Typhoon Warning Center (JTWC) estimates that the low-level center of System 91B is near 10.1 north latitude and 76.4 east longitude, just 20 nautical miles (23.0 miles/37.0 km) north-northeast of Cochin, India. The center of the storm has moved to the north over the last day and is about 15 nautical miles (17.2 miles/27.8 km) closer to Cochin than it was on May 7, indicating that it is a very slow moving system.

On May 8, JTWC's website noted "upper-level analysis (of the atmosphere) indicates a marginal environment with moderate, easterly vertical wind shear offset by strong diffluence (upper air flowing off or away from the center of the storm).

Maximum sustained surface winds are estimated between 10 to 15 knots (11.5 to 17.2 mph/18.5 to 27.7 kph) as they were on May 7, so the winds have not weakened. Minimum sea level pressure is estimated to be near 1006 millibars.

As System 91B continues to linger over land, it continues to have a low chance for developing into a significant tropical cyclone within the next 24 hours.

Text credit:  Rob Gutro
NASA's Goddard Space Flight Center


[image-51]May 07, 2014 - NASA Sees System 91B Making Landfall in Southwestern India

A tropical low was affecting southern India and Sri Lanka on May 6 at 0809 UTC when the Tropical Rainfall Measuring Mission satellite called TRMM flew above it. By May 7, System 91B moved over southwestern India and became less organized.

TRMM's Precipitation Radar revealed that rain was falling at a rate of 66 mm (2.6 inches) per hour in the stormy area south of India (5.2 north latitude and 77.1 east longitude). TRMM PR saw the tallest thunderstorm towers over Sri Lanka where heights were pushing to altitudes above 13 km (8 miles).

On May 7 at 12:30 UTC/8:30 a.m. EDT, System 91B was located near 10.0 north latitude and 76.9 east longitude, approximately 35 nautical miles (40 miles/64.8 km) east of Cochin, India.

According to the Joint Typhoon Warning Center, today's animated infrared satellite imagery shows the system has moved inland over the southwestern interior of India. As a result, the large low-level center of circulation is now ill-defined and the remnant thunderstorms are over the western quadrant of the storm.

Maximum sustained surface winds are estimated at 10 to 15 knots (11.5 to 17.2 mph/18.5 to 27.7 kph) and minimum sea level pressure is estimated to be near 1006 millibars. As a result of the low moving over land, the chances for it to organize into a tropical depression over the next 24 hours have dropped from medium to low.

The TRMM satellite was launched by NASA and JAXA in 1997 with the first earth orbiting active/passive instrument package to study the intensity and structure of tropical rainfall. The Global Precipitation Mission satellite that was launched on February 27, 2014 will continue TRMM's highly successful mission of monitoring precipitation from space.

Text credit:  Hal Pierce/ Rob Gutro
NASA's Goddard Space Flight Center

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91B in the Northern Indian Ocean
On May 6, the TRMM satellite saw that some rain in System 91B was falling at a rate of 66 mm (2.6 inches) per hour in the stormy area southwest of India The tallest thunderstorm towers over Sri Lanka were above 13 km (about 8 miles).
Image Credit: 
SSAI/NASA, Hal Pierce
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91B lingering over India
NASA's Terra satellite passed over System 91B over southwestern India and the MODIS instrument captured this visible image on May 8 at 05:40 UTC.
Image Credit: 
NASA Goddard MODIS Rapid Response Team
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[image-78]
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Page Last Updated: May 8th, 2014
Page Editor: Lynn Jenner