NASA - National Aeronautics and Space Administration

Nov. 14, 2008

Tropical Storm 05B to Make Landfall in Eastern India

The fifth tropical cyclone in the Indian Ocean region is poised to make landfall in eastern India over the weekend of Nov. 15-16. Tropical Storm 5B was swirling in the Bay of Bengal and headed north on a path for landfall Saturday, the 15th.

On Friday, Nov. 14 at 600 Zulu Time (1 a.m. EST), Tropical Storm 05B had maximum sustained winds near 40 knots with gusts to 50 knots. It was moving in a northerly direction at 5 knots (6 mph). It was located approximately 280 nautical miles east of Madras, India, near 13.4 degrees north latitude, and 85.1 degrees east longitude.

NASA Frigid Cloud Temperatures an Indicator of Tropical Storm 05B Strengthening

Forecasters are looking at 05B's cloud temperatures, because it's in a favorable environment to strengthen. Some of the satellite data they're using comes from the Atmospheric Infrared Sounder (AIRS) instrument that flies on NASA's Aqua satellite. The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

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Credit: NASA JPL The infrared image, taken on Nov. 14 at 12:59 p.m. EST (17:59 UTC) shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the storm. Those temperatures are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue areas are around 240 degrees Kelvin, or minus 27F.

Some of 05B's clouds (in blue) are already over India, as seen in the infrared satellite image. The visible image, also created from AIRS shows the swirl of clouds that mark a tropical storm.

The Joint Typhoon Warning Center uses cloud temperature as one factor in determining whether a tropical cyclone is strengthening. When cloud temperatures get colder, it means that clouds are getting higher. Building clouds indicate a lot of "uplift" in the atmosphere and stronger thunderstorms.

AIRS infrared signal doesn't penetrate through clouds, so where there are clear skies AIRS reads the infrared (heat) signal from the ocean and land surfaces, revealing warmer temperatures (colored in orange and red). The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are). Tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

What Does AIRS Water Vapor Imagery Show?

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Credit: NASA JPL Satellite imagery of water vapor showed good outflow (Air that flows outward) from the storm and "improved convective banding." That means that the thunderstorms that form the rain "bands" around the center of the storm were getting stronger and more organized. The Joint Typhoon Warning Center, the organization that provides the forecasts for tropical cyclones in this region, noted that the environment is favorable for the strengthening of Tropical Storm 05B.

Tropical Cyclone 05B is expected to make landfall in east central India on Saturday, Nov. 15, between the cities of Vsakhapatnam to the north, and Madras to the south. The Joint Typhoon Warning Center expects that Tropical Cyclone 05B will dissipate "as a significant tropical cyclone over land" by 1 p.m. EST on Nov. 15.

Text credit: Rob Gutro (from JTWC reports)/NASA's Goddard Space Flight Center