Tropical Storm Estelle continues to strengthen in the Eastern Pacific Ocean and NASA satellite imagery showed what appears to be a developing eye in the storm.
On July 17 at 09:30 UTC (5:30 a.m. EDT), the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi NPP satellite captured an image of Tropical Storm Estelle. The VIIRS image showed the hint of a cloud-covered eye in Estelle surrounded by a ring of powerful thunderstorms. The Suomi NPP satellite is managed by NASA and NOAA with support from the U.S. Department of Defense.
On July 17 at 5 a.m. EDT, infrared data showed Estelle's cloud tops near the center were as cold as minus 80 Celsius (minus 112 Fahrenheit) and colder during the past couple of hours. On July 18 at 0905 UTC (5:05 a.m. EDT) the Atmospheric Infrared Sounder or AIRS instrument that flies aboard NASA's Aqua satellite provided more infrared temperature data on Estelle. NHC forecaster Brown said, "Although the cloud tops are not as cold as they were yesterday, the area of convection is a little more symmetric around the center indicating that the northwesterly (wind) shear is relaxing."
On July 18 at 11 a.m. EDT (1500 UTC), the center of Tropical Storm Estelle was located near latitude 17.7 North, longitude 114.9 West. That's about 485 miles (780 km) southwest of the southern tip of Baja California, Mexico. Estelle is moving toward the west-northwest near 10 mph (17 kph) and the National Hurricane Center (NHC) said that this general motion is expected to continue for the next couple of days.
Maximum sustained winds are near 70 mph (110 kph) making it just shy of hurricane-strength. NHC said strengthening is likely during the next day or so, and Estelle is forecast to become a hurricane later today or tonight.
At 11 a.m. EDT on July 18, an automated weather observing site on Clarion Island recently reported sustained winds of 59 mph (95 kph) and a gust to 82 mph (133 kph). The estimated minimum central pressure is 991 millibars. A pressure of 995.3 millibars was recently reported on Clarion Island.
Estelle is only expected to be a short-lived hurricane. Within a day and a half to two days, Estelle is forecast to move over cooler sea surface temperatures and later a more stable air mass. Both of those factors are expected to weaken the storm.