Categorized | Environment, Sci-Tech

Hurricane Season 2009: Tropical Depression 4E (Eastern Pacific)

Fourth Tropical Depression Likely to Become Carlos Over the Weekend

Video by NOAA-NASA GOES Project

By Rob Gutro, NASA’s Goddard Space Flight Center

This AIRS Infrared image from July 10 shows the coldest, highest thunderstorm cloud tops of TD#4E in purple. Image credit: NASA JPL, Ed Olsen

This AIRS Infrared image from July 10 shows the coldest, highest thunderstorm cloud tops of TD#4E in purple. Image credit: NASA JPL, Ed Olsen

The eastern Pacific Ocean’s fourth tropical depression formed in the early morning hours on Friday, July 10, but will likely strengthen into Tropical Storm Carlos over the weekend of July 11-12.

Forecasters at the National Hurricane Center said that the fourth tropical depression (TD#4E) of the eastern Pacific hurricane season is in a good environment that will promote strengthening: low wind shear and warm ocean waters in the open ocean. TD#4E is away from land and poses no threat to any landmasses as it continues on a westward track further away from land.

At 11 a.m. EDT on July 10, maximum sustained winds of TD#4E are near 35 mph with higher gusts. According to the National Hurricane Center, “Some strengthening is forecast and the depression will likely become Tropical Storm Carlos later today or on Saturday.”

The center of TD#4E was located near latitude 10.4 north and longitude 112.8 west or about 885 miles south-southwest of the southern tip of Baja California. The depression is moving west near 12 mph further out to sea, and is expected to continue in that direction during the next two to three days.

Satellite imagery from NASA’s Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA’s Aqua satellite indicated cold high clouds and thunderstorms in TD#4E. AIRS captured an infrared image of the depression on July 10 at 4:53 a.m. EDT (0853 UTC) that showed a circular cloud pattern, indicating a storm that was becoming better organized.

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.

Because the infrared imagery reads temperature it can also tell how warm the ocean waters are the surround a storm. Warmer temperatures are also false-colored and an orange color represents temperatures of 80F (300 degrees Kelvin).

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