Two weather systems designated as Invest 92L and Invest 93L are being monitored for possible development into tropical cyclones. Invest 92L is a tropical wave that is speeding toward the Windward Islands. At 2:00 p.m. EDT on Sunday the center of Invest 92L was located at latitude 7.3°N and longitude 49.4°W which put it about 800 miles (1290 km) east-southeast of the Windward Islands. It was moving toward the west-northwest at 24 m.p.h. (39 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1008 mb.
Invest 93L consists of a broad area of low pressure over the northwestern Caribbean Sea. At 2:00 p.m. EDT on Sunday the surface center of Invest 93L was located at latitude 19.0°N and longitude 87.1°W which put it about 145 miles (230 km) south of Cancun, Mexico. It was moving toward the north-northwest at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1006 mb.
Invest 92L is a tropical wave and it has not yet develop a well defined surface center. There is some evidence of cyclonic rotation on visible satellite imagery and there could be a center in the middle levels of the circulation. Most of the stronger thunderstorms are located north and west of the center. The are some bands of showers and thunderstorms south and west of the center. There is some upper level divergence from the thunderstorms north and west of the center, but it is not well developed at the current time.
Invest 92L is in an environment that is moderately favorable to development of a tropical cyclone. It is moving over water where the Sea Surface Temperature is near 28°C. It is in a region of rapid easterly flow, but the wind speed is fairly similar at all levels. So, there is not a lot of vertical wind shear. The rapid easterly flow could be inhibiting the formation of a well defined center of circulation. Invest 92L will be in a moderately favorable environment for about another 36 hours. An upper level trough over the eastern Caribbean Sea will create increased vertical wind shear when Invest 92L reaches that location. The National Hurricane Center is indicating that there is a 60% probability that Invest 92L will develop into a tropical cyclone during the next two days.
Invest 92L is being steered rapidly toward the west-northwest by a subtropical high north of it. A fairly quick motion toward the west-northwest is expected to continue for the next few days. On its anticipated track Invest 92L could be near the Windward Islands by late Monday. Even it if does not develop into a tropical cyclone, the system will bring gusty winds and locally heavy rain to those islands.
The structure of Invest 93L is much more complicated. There is a very broad but weak surface low pressure system over the Yucatan peninsula and the center of that low is being used as the center of the Invest. However, there is a strong mid-level center of circulation near latitude 18.7°N and longitude 82.9°W which is about 115 miles (185 km) west-southwest of Grand Cayman. Invest 93L is producing winds to near tropical storm force and those winds are occurring in thunderstorms associated with the mid-level circulation. It is possible that downdrafts in those thunderstorms could transport enough momentum to the surface to generate a new surface center beneath the mid-level center.
Invest 93L is moving in an environment that will be favorable for the development of a tropical cyclone. An upper level ridge is building between the trough over the eastern Caribbean Sea and another upper level trough over the northwestern Gulf of Mexico. The trough over the northwestern Gulf is producing strong southwesterly winds which are causing vertical wind shear over the surface low over the Yucatan peninsula. However, the upper level ridge is producing an area of slower winds over the mid-level center and there is less vertical wind shear there. In fact, the upper level ridge is enhancing upper level divergence over the mid-level center. If that continues, surfaces pressure will begin to decrease in that region. The National Hurricane is indicating that there is a 70% probability of development of a tropical cyclone or a subtropical cyclone during the next two days.
Invest 93L is moving slowly north-northwestward around the western end of the subtropical high over the Atlantic Ocean. A general north-northwesterly motion is expected to continue for another day or two, but there is some spread in the guidance from the numerical models. If a cyclone forms from the surface low over the Yucatan peninsula, then the greatest risk would be to the western Gulf of Mexico. If a new surface center forms farther east under the mid-level center, then there would be a greater risk for the central and eastern Gulf of Mexico. Interests around the Gulf should monitor Invest 93L.