When NASA’s Aqua satellite flew over Guillermo in the Eastern Pacific Ocean late at night on August 13, the infrared instrument that captures cloud temperatures showed an eye the storm’s center, indicating a strengthening storm. Guillermo became a hurricane shortly afterward.

Aqua’s Atmospheric Infrared Sounder (AIRS) is actually able to measure a cloud’s temperatures from space, and on Aug. 13 at 5:11 p.m. EDT (21:11 UTC) the image AIRS captured revealed very high clouds, towering thunderstorms with very cold temperatures. Both very high clouds and very cold temperatures indicate strong tropical cyclones, because storms are made up of hundreds of thunderstorms.

In infrared imagery, NASA’s false-colored purple clouds are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F). The blue colored clouds are about 240 Kelvin, or minus 27F. AIRS visualized most of Guillermo’s clouds in purple, meaning they’re very cold and very high.

On Friday, August 14 at 5 a.m. EDT, Guillermo had maximum sustained winds near 75 mph and will strengthen a little, but then it’s going to run into colder waters. Surface water temperatures colder than 80 degrees Fahrenheit are too cold to provide power to tropical cyclones to keep their strength, so he’ll weaken over the weekend.

Hurricane Guillermo was located 1,100 miles west-southwest of the southern tip of Baja California, near 17.6 north latitude and 125.9 west longitude. Guillermo was moving west near 15 mph and will turn west-northwest over the weekend. Estimated minimum central pressure is 987 millibars.

Over the weekend of Aug. 15-16, Guillermo will encounter the colder waters and will drop back to tropical storm status and continue to weaken.

The Atlantic Ocean’s second Tropical Depression has been on shaky ground since it formed early in the week of August 11. It meandered westward from the African coast and maintained its tropical depression status until weakening to a remnant low. Now it has the potential to come back. In addition to Tropical Depression 2, there are three other areas forecasters are watching in the Atlantic Basin. Residents of Florida should particularly be watchful as there’s a potential for tropical development on both the east and west coasts this weekend.

At 5 p.m. EDT on Aug. 13, Tropical Depression 2 (TD2) in the Atlantic Ocean was downgraded to a remnant low pressure area. If you’re a tropical cyclone, you can’t get any lower than that, aside from total dissipation. At that time, TD2′s remnants were about 930 miles west of the southernmost Cape Verde Islands off the African coast.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite measures cloud top temperature and pressure, and it captured a look at the remnants of Tropical Depression 2, and it was still maintaining somewhat of a circular shape. In infrared imagery, NASA’s false-colored purple clouds are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F). The blue colored clouds are about 240 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.In addition to TD2′s struggle for life, there other three areas forecasters will be watching over the weekend and residents of Florida should keep an eye on both coasts for tropical development of two of the three systems.

TD2 AIRS image> View larger image
The AIRS instrument on NASA’s Aqua satellite captured an image of Tropical Depression 2′s cloud temperatures on August 13 at 2:17 p.m. EDT. Credit: NASA JPL, Ed Olsen Farthest from the U.S. is the area of showers and thunderstorms with the greatest potential for developing into a tropical cyclone over the weekend. On Aug. 14, that area of disturbed weather was located 250 miles west-southwest of the southern Cape Verde Islands. It has a “greater than 50 percent chance of developing.”

Much closer to the U.S. are two areas with less than a 30 percent chance of development. One area of showers and thunderstorms are associated with a tropical wave that stretches from the Bahamas to Hispaniola. The other area is in the Gulf of Mexico, associated with a weak elongated area of low pressure. The area is centered off the coast from Tampa, Florida. Residents of Florida should be on watch this weekend, as tropical development is possible around them on both the east and west coasts. For the latest updates,