Tropical Storm John formed quickly off the coast of southwestern Mexico around the same time as Ileana, which is just east of John. Infrared data from NASA's Aqua satellite provided forecasters with temperature data that showed the cloud top temperatures in John had cooled indicating the storm was strengthening.
John formed as a tropical depression on Sunday, Aug. 5 about 320 miles (515 km) south-southwest of Manzanillo, Mexico.
On Aug. 6 at 4:40 a.m. EDT (0840 UTC) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Terra satellite analyzed Tropical Storm John's cloud top temperatures in infrared light. MODIS found cloud top temperatures of strongest thunderstorms were as cold as or colder than minus 80 degrees Fahrenheit (minus 62.2 Celsius) around the center. Cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.
National Hurricane Center (NHC) Forecaster Blake noted on Aug. 6 at 5 a.m. EDT that "The convective pattern of John has become significantly better organized during the past several hours, with a large central dense overcast forming and cloud top temperatures to minus 85 degrees Celsius."
At 5 a.m. EDT (0900 UTC) on Aug. 6, the center of Tropical Storm John was located near latitude 15.1 North, longitude 107.3 West. John is located about 335 miles (540 km) southwest of Manzanillo, Mexico.
Because John is close enough to the coast, it is expected to produce dangerous ocean conditions there. Swells generated by John are expected to begin affecting the coast of southwestern Mexico during the next day or so. These swells are likely to cause life-threatening surf and rip current conditions
The National Hurricane Center (NHC) said John is moving toward the west-northwest near 8 mph (13 km/h) and a faster northwestward motion is forecast for the next few days. John's estimated minimum central pressure is 999 millibars.
Maximum sustained winds have increased to near 60 mph (95 kph) with higher gusts. John is forecast to become a hurricane later today and a major hurricane on Tuesday.
For updated forecasts on John, visit the NHC website: http://www.nhc.noaa.gov