A complex low pressure system over the southern Gulf of Mexico is showing signs of greater organization.  A reconnaissance aircraft investigated the system on Sunday afternoon and found evidence of a broad area of low pressure at the surface and winds to tropical storm force northeast of the low.  The official designation for this system is Invest 91L.  At 11:00 p.m. EDT on Sunday night the approximate center of the broad low was located at latitude 22.7°N and longitude 90.2°W which put it about 540 miles (870 km) south-southeast of Galveston, Texas and about 540 miles (870 km) east-southeast of Brownsville, Texas.  The low was moving toward the northwest at 14 m.p.h. (23 km/h).  The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were gusts to 50 m.p.h. (80 km/h).  The minimum surface pressure was 1007 mb.

Invest 91L is a complex system which includes an upper level low over the southern Gulf of Mexico and a broad area of low pressure at the surface.  Clusters of thunderstorms are forming intermittently east and north of the center of circulation.  The pressure gradient between a strong high pressure system centered over the Atlantic Ocean and the developing surface low is causing the strongest winds to be found in the northeastern part of Invest 91L.  The upper level low is causing the system is to exhibit a more subtropical mode of formation rather a typical tropical genesis.  However, more thunderstorms are beginning to develop closer to the center of circulation and the National Hurricane Center is giving Invest 91L an 80% chance of becoming a tropical cyclone.  The low is moving over water where the Sea Surface Temperature (SST) is around 27°C to 28°C, which is warm enough to support the development of a tropical cyclone.  The upper level low was generating vertical wind shear, but if the surface low develops under the center of the upper low, then the wind shear will have less of an effect.  If more thunderstorms form near the center of circulation and a warm core develops, then the low could be classified as a tropical storm on Monday.  Some intensification is possible because of the warm SSTs.

An upper level ridge centered over the southeastern U.S. is expected to steer the system toward the northwest and it could make landfall on the coast of Texas in 24 to 48 hours.  The primary risk will be locally heavy rainfall, although a minor storm surge could occur in some coastal locations.