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Hurricane Season 2010: System 94B (Northern Indian Ocean)
12.08.10
 
December 8, 2010

System 94B Dissipates, Remnants Producing Isolated Showers

TRMM captured rainfall rates within System 94B near India's east coast on Dec. 7 › View larger image
NASA's TRMM satellite captured rainfall rates within System 94B near India's east coast on Dec. 7 at 0123 UTC. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour. Red areas are heavy rainfall at almost 2 inches per hour.
Credit: NASA/SSAI, Hal Pierce
System 94B has dissipated off the southeastern coast of India and its remnant showers and thunderstorms are affecting extreme southeastern India and Sri Lanka today, Wednesday, Dec. 8. Isolated showers are occurring in the southern and southeastern part of the state of Tamil Nadu, India and over Sri Lanka today as the remnants of System 94B fizzle out. In Pondicherry, forecasters are calling for scattered showers Wednesday night with only as much as six tenths of an inch of rain.On Thursday, as much as half an inch of rain is possible there. Farther southwest and inland, the city of Tiruchirapalli is expecting widely scattered thunderstorms only today and then sunshine and clear skies the rest of the week. In the city of Madurai, located in extreme southern India, the dissipating low pressure area is expected to produce isolated showers over the next day, then sunshine takes over. System 94B never developed into a tropical depression.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD



December 7, 2010

NASA Satellites See Heavy Rainfall and Displaced Thunderstorms in System 94B

TRMM captured rainfall rates within System 94B near India's east coast on Dec. 7 › View larger image
NASA's TRMM satellite captured rainfall rates within System 94B near India's east coast on Dec. 7 at 0123 UTC. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour. Red areas are heavy rainfall at almost 2 inches per hour.
Credit: NASA/SSAI, Hal Pierce
System 94B's strongest convection and highest, coldest cloud tops remained off-shore › View larger image
The AIRS instrument on NASA's Aqua satellite captured this image of System 94B's cold cloud tops on Dec. 6 at 3:11 p.m. EST. Most of the strongest convection and highest, coldest cloud tops remained off-shore over the waters of the western Bay of Bengal. Those cloud top temperatures were as cold as or colder than -63 degrees Fahrenheit (-52 Celsius) and appear in purple.
Credit: NASA/JPL, Ed Olsen
System 94B has not been classified as a tropical depression, but NASA satellite data has shown that it is creating heavy rainfall near India's southeastern coast. A second NASA satellite revealed that strong wind shear is continuing to push convection to the northwest of System 94B's center of circulation.

The Tropical Rainfall Measuring Mission (TRMM) satellite viewed an area of thunderstorms associated with System 94B near the east coast of India in the Bay of Bengal on December 7 at 0123 UTC. Data from TRMM's Precipitation Radar (PR) and Microwave Imager (TMI) showed that some severe thunderstorms in this area off the Indian coast were producing very heavy intense rainfall of over 50mm/hr (~2 inches/hour).

The TRMM satellite's main purpose is to measure rainfall over the tropics but it has also proven very valuable for monitoring development of tropical cyclones. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

On Dec. 7 the center of System 94B was located about 240 nautical miles east-southeast of Chennai, India near 11.4 North latitude and 84.0 East longitude.

NASA's Aqua satellite captured an image of System 94B and continued to show that its main convection (rapidly rising air that forms the thunderstorms that power a tropical cyclone or low pressure area) are northwest of the storm's center of circulation. That's an indication that the strong wind shear that was battering the low pressure area earlier this week is still continuing.

The Atmospheric Infrared Sounder (AIRS) instrument captured an image of System 94B's cold cloud tops on Dec. 6 at 20:11 UTC (3:11 p.m. EST). The image showed most of the strongest convection, and highest, coldest cloud tops remained off-shore over the waters of the western Bay of Bengal. The coldest cloud top temperatures were as cold as or colder than -63 degrees Fahrenheit (-52 Celsius).

The AIRS infrared image did show that there were some strong thunderstorms along the immediate southeastern coast of India, where heavy rain was falling in the state of Tamil Nadu, India.

Tamil Nadu is one of the 28 states and lies in the southernmost part of the Indian Peninsula. Its capital city is Chennai located in the northeastern part of the state.

The Joint Typhoon Warning Center (JTWC) maintains forecast responsibility for this storm. The JTWC noted that maximum sustained winds at the surface are estimated between 20 to 25 knots (23 to 28 mph) and minimum sea level pressure is near 1004 millibars.

Today's JWTC forecast said, "Based on the sheared convection and relatively high vertical wind shear, the potential for the development of a significant tropical cyclone within the next 24 hours remains poor."

So far this year five tropical cyclones have spawned in the Bay of Bengal. Tropical cyclones often form in the Bay of Bengal during the month of November but this area of low pressure isn't expected to intensify to tropical storm strength.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD



December 6, 2010

NASA's Infrared Satellite Imagery Shows Strong Convection in System 94B

System 94B's eastern half has the strongest convection and thunderstorms › View larger image
Infrared data from NASA's Aqua satellite on Dec. 6 at 07:59 UTC (2:59 a.m. EST) showed that System 94B's eastern half has the strongest convection and thunderstorms, as cloud tops there are so high that they are at least -63 degrees Fahrenheit (-52 Celsius) or colder (purple).
Credit: NASA/JPL, Ed Olsen
A low pressure system has been moving through the Northern Indian Ocean over the last couple of days and infrared satellite imagery from NASA's Aqua satellite revealed strong convection in its eastern side and strong wind shear.

At 1800 UTC (1 p.m. EST) on Dec. 6, the center of the low pressure area known as 94B was located east of India's southeast coast over the Bay of Bengal. 94B's center is about 225 miles northeast of Colombo, Sri Lanka near 11.4 North and 84.0 East.

When NASA's Aqua satellite passed over the low on Dec. 6 at 07:59 UTC (2:59 a.m. EST), its Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of the storm's clouds. The image revealed that the western half of the low is already over land as a result of strong wind shear, while the eastern half of the storm and its center of circulation are over open waters in the Bay of Bengal. AIRS data showed that the eastern half of the low had the strongest convection and thunderstorms as infrared data revealed that cloud tops are so high that they are at least -63 degrees Fahrenheit (-52 Celsius) or colder.

Vertical wind shear in the area is moderate to strong, so the convection and strongest thunderstorms have been pushed to the northwest of the center as a result of those strong southeasterly winds.

Because of the wind shear and its proximity to the coast, chances are poor that it will consolidate into a tropical cyclone. The minimum sea level pressure in the vicinity of the storm is estimated to be near 1004 millibars.

Despite the fact that it may never become organized enough to be classified a tropical depression, it will still bring periods of moderate rainfall and some gusty winds to the coastal areas. Some gusts could be as strong as 25 knots (28 mph/ 46 km/hour). The forecast for Pondicherry, which is located in the southeastern region of India calls for widely scattered showers and thunderstorms over the next couple of days from this system. Pondicherry is a city, an urban agglomeration and a municipality in Pondicherry District in the union territory of Puducherry and residents should keep an eye on System 94B as it approaches.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD