November 19, 2009
NASA Satellite Sees a Disturbance Form 8 Degrees North of the Equator
Hurricane Season 2009: System 92W (Western Pacific Ocean)
NASA's Aqua satellite noticed that a new tropical disturbance formed today, November 19, just 8.1 degrees north of the Equator in the western Pacific Ocean. It is designated "System 92W" right now, but if it does mature into a tropical cyclone it will get a name.
System 92W is located about 230 miles east of Kwajalein, near 8.1 north and 171.5 east. Kwajalein is an atoll that's part of the Republic of the Marshall Islands. It's about 2,100 nautical miles southwest of Honolulu, Hawaii.
NASA's Aqua satellite flew over System 92W on November 19 at 8:23 a.m. ET (1323 UTC). Infrared imagery from the Atmospheric Infrared Sounder (AIRS) instrument on the Aqua satellite found some strong convection and high, cold clouds and thunderstorms in its center. Cloud-top temperatures are important because they tell forecasters how high thunderstorms are, and the higher the thunderstorm, the colder the cloud tops and the more powerful the thunderstorms.
The Joint Typhoon Warning Center, the organization that forecasts for tropical cyclones in the Western Pacific Ocean, noted today that "Animated multispectral satellite imagery depicts a developing low-level circulation center with isolated bursts of deep convection over the center." AIRS was satellite instrument that identified that strong convection in the center of the storm.
The Advanced Microwave Sounding Unit, another instrument on NASA's Aqua satellite noticed some "weak convective banding" around the center of 92W. Banding is a feature of a tropical cyclone that involves thunderstorms that wrap around the center of circulation in a spiral pattern.
Satellite data helped forecasters see that 92W is in an environment with "moderate vertical wind shear." Wind shear is when winds are blowing at different levels of the atmosphere in different directions that can weaken or tear a storm apart.
The bottom line is that there is a fair chance that 92W will develop into a tropical cyclone in the next day or two.
Rob Gutro, NASA/Goddard Space Flight Center