A broad area of low pressure designated as Invest 91E slowly organized south of Mexico on Tuesday. At 8:00 p.m. EDT on Tuesday the center of Invest 91E was located at latitude 13.7°N and longitude 97.9°W which put it about 220 miles (350 km) south-southeast of Acapulco, Mexico. Invest 91E was moving toward the north-northeast at 6 m.p.h. (10 km/h). The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h). The minimum surface pressure was 1007 mb.
Invest 91E consisted of a broad area of low pressure located south of Mexico. The Invest did not have a well organized center of circulation. Instead there was a broad area of counterclockwise rotation. Many of the thunderstorms were in bands in the outer periphery of the circulation. A few thunderstorms were beginning to form closer to the center and there were signs that some bands of showers were beginning to organize nearer to the core of the system.
Invest 91E will be moving through an area that will be favorable for development of a tropical cyclone. It will move over water where the Sea Surface Temperature is near 30°C. Invest 91E will be moving underneath the western portion of an upper level ridge. The ridge will produce southerly winds which will blow toward the top of the circulation. The southerly winds will cause some vertical wind shear. However, the effects of the shear could be offset by upper level divergence created by the upper level ridge. Invest 91E has a good chance to develop into a tropical depression and the National Hurricane Center is indicating that there is a 70% probability of a depression forming during the next 48 hours.
A subtropical ridge east of Invest 91E is steering the system slowly toward the north-northeast. A general northerly motion is expected to continue for another 24 to 48 hours. On its anticipated track Invest 91E will approach the southern coast of Mexico. It could bring locally heavy rain when the outer bands on the northern side of the circulation move over land.