March 9, 2013
NASA Satellites Track Tropical Cyclone Sandra As She Nears New Caledonia
redOrbit Staff & Wire Reports - Your Universe Online
The storm formerly known as Cyclone 19P was renamed Sandra on Friday, and NASA officials are warning residents of New Caledonia to brace for strong winds, heavy rain and possible flooding early next week.
Using the Atmospheric Infrared Sounder instrument on board the Aqua satellite, officials from the US space agency announced they had captured an infrared image of the cyclone´s cloud top temperatures on March 8.
The image, which was taken shortly after noon Eastern time, showed “strong thunderstorms around Sandra´s center and in a band east of the center appeared as cold as -63 Fahrenheit (-52 Celsius), and are indicative of heavy rainfall“¦ As cloud tops grow taller in the troposphere, their temperatures grow colder (because temperatures drop with altitude in the troposphere).
“High cloud tops indicate a strong uplift of air that helps build the thunderstorms that make up a tropical cyclone. When uplift is strong, cloud tops sometimes punch through the top of the troposphere into the tropopause and even into the stratosphere,” they added. “Satellite imagery also showed central convection deepened (strengthened) over the storm's center since the previous day, indicating that Sandra is in a mode of strengthening.”
Furthermore, information collected by the Special Sensor Microwave Imager/Sounder satellite instrument under a US Defense Department program, illustrated that an eye was developing in the cyclone early Friday morning.
As of 7am EST Friday, Sandra´s center was located near 14.9 degrees south latitude and 157.7 degrees east longitude, NASA officials reported. It was 645 nautical miles northwest of Noumea, the capital and largest city of the French territory, and was moving eastward at a speed of six knots (or roughly seven miles per hour). Sandra´s maximum sustained windspeeds had increased to nearly 60 knots (or 69 miles per hour), NASA said.
NASA said forecasters with the Joint Typhoon Warning Center noted in an update later Friday (Mar 8) that Sandra would likely intensify over the next three days before weakening. The latest info puts the path of Sandra over New Caledonia on March 12, and will bring heavy rain, strong winds and rough surf, as well as possible flooding.
On Wednesday night, shortly before 7:30pm EST, NASA´s Tropical Rainfall Measuring Mission (TRMM) observed regions of heavy rainfall in what was then low pressure System 92P. According to the agency, TRMM was able to capture rainfall rates just a few hours before the low pressure system became Tropical Cyclone 19P. At that time, precipitation was falling at 2 inches per hour near the center of circulation, and some of the more powerful thunderstorms were more than nine miles high.