Another Eastern Pacific Storm May Join Carlos

By Rob Gutro, NASA’s Goddard Space Flight Center

The AIRS instrument on the Aqua satellite captured the eastern half of the low pressure area's cold clouds (in blue and purple) in the Eastern Pacific Ocean on July 14 at 4:29 a.m. EDT (08:29 UTC). The light blue area to the left of the storm was an area outside the satellite's track. Credit: NASA JPL

Hurricane Carlos may soon have company in the form of another named storm in the Eastern Pacific Ocean. A broad area of low pressure to the east-northeast of Carlos looks like it may get organized over the next day or two and become tropical depression 5E.

Hurricane Carlos is stirring up waters in the open Eastern Pacific Ocean about 1,465 miles southwest of the southern tip of Baja California, while showers and thunderstorms associated with another low pressure area located several hundred miles southwest of Manzanillo, Mexico may come together into a tropical storm.

At 8 a.m. EDT on July 14, the National Hurricane Center said “Conditions remain favorable for further development of this system…and a tropical depression could form in the next day or so as it moves west or west-northwestward at 10 to 15 mph.” The Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA’s Aqua satellite captured the low pressure area’s high cold clouds in the Eastern Pacific Ocean on July 14 at 4:29 a.m. EDT (08:29 UTC).

Infrared imagery is useful to forecasters because it shows the temperature of the clouds. NASA false-colors clouds at different heights in the infrared satellite images, so that in AIRS imagery, the highest clouds appear purple, and the second highest clouds appear in blue. How does infrared imagery know how high clouds are in the sky? The coldest ones are higher in the sky (because in the troposphere, the lowest layer of atmosphere where weather happens, temperatures fall the higher up you go until you get to the stratosphere).

In infrared imagery, NASA’s false-colored purple clouds are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue colored clouds are about 240 degrees Kelvin, or minus 27F. The colder the clouds are, the higher they are, and the more powerful the thunderstorms are that make up the cyclone.

The chance for this low to become a tropical depression over the next two days is greater than 50 percent. Forecasters at the National Hurricane Center and NASA satellites are keeping their eyes on it.

GOES-11 Image taken July 15, 2009 at 0600UTC. Image courtesy of NASA-GOES Project