Irwin was still a hurricane when the NASA-NOAA Suomi NPP satellite passed over the Eastern Pacific Ocean on July 25. Eighteen hours later, Irwin weakened to a tropical storm.
The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the NASA-NOAA Suomi NPP satellite captured a visible light image of Irwin on July 25 at 5:54 p.m. EDT (2154 UTC). The Suomi NPP image showed that Irwin had improved over the previous three hours. Although a well-defined eye showing up in infrared imagery, it appeared to be obscured by high clouds in the NPP image. There was also an elongated band of thunderstorms extending around the western and northern side of the circulation.
Satellite imagery and microwave data on July 26, 2017 showed that Irwin's cloud pattern had significantly deteriorated since July 25. Irwin now consists of a tight circulation center located just to the south of an area of deep, but not too well organized, convection.
At 11 a.m. EDT (1500 UTC), the center of Tropical Storm Irwin was located near 15.6 degrees north latitude and 122.1 degrees west longitude. That's about 940 miles (1,515 km) west-southwest of the southern tip of Baja California, Mexico. Irwin was moving toward the west-southwest near 7 mph (11 kph), and this general motion is expected to continue during the next 48 hours. Maximum sustained winds have decreased to near 65 mph (100 kph) and the National Hurricane Center (NHC) said that some weakening is possible today, but no significant change in strength is anticipated thereafter.
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By Rob Gutro
NASA's Goddard Space Flight Center