A weather system over the southeastern Gulf of Mexico could bring heavy rain to the southeastern U.S. this week. An upper level low over the eastern Gulf of Mexico could transfer enough kinetic energy down to the lower troposphere to spin up a low at the surface. Air flowing around the eastern side of the low is contributing to upper level divergence over Florida. The divergence enhanced rising motion over Florida and rain fell over parts of the southern and central portions of that state.
The weather system is forecast to move slowly northward during the next several days. The Sea Surface Temperatures in the southeastern Gulf of Mexico are 24°C to 26°C. There is enough energy in the upper levels of the water to support the formation of a tropical cyclone. The upper level low will create southerly winds which will cause moderate vertical wind shear. The shear will inhibit development, although those winds could contribute to upper level divergence to the east of the weather system. Upper level divergence could allow the surface pressure to decrease and a low pressure system could form at the surface. The National Hurricane Center (NHC) issued a special Tropical Weather Outlook on Sunday afternoon on the weather system. NHC indicated the probability was 40% that a tropical or subtropical cyclone could form during the next five days.
Guidance from numerical models suggest that the weather system will move slowly northward over the eastern Gulf of Mexico during the next few days. Counterclockwise rotation around the low will transport moist air northward on the eastern side of the low. The moist air combined with upper level divergence will create the potential for locally heavy rainfall over the southeastern U.S. Heavy rain could result in floods in some locations.
There are two areas to watch for the potential development of a tropical cyclone during the next week. One location to watch for potential development is the area around the western Caribbean Sea, Yucatan peninsula and southern Gulf of Mexico. The other area to watch is the tropical Atlantic between Africa and the Lesser Antilles.
Numerical models have been suggesting possible development of an area of low pressure somewhere over the western Caribbean Sea, Yucatan peninsula or southern Gulf of Mexico. The scenario suggested by the models includes a surge of southerly winds across Central America, which contributes to the spinning up of an area of low pressure. There are currently strong westerly winds in the upper levels over this area. The strong vertical wind shear will prevent development of a tropical cyclone in the short term. An upper level ridge could develop over the area in several days. If that happens, the wind shear would decrease. Some runs of the numerical models create a broad, weak area of low pressure, which would primarily be a rain threat for the Yucatan peninsula and nearby regions. Other models develop a low pressure system that is a little stronger, although those lows also weaken when they move over the Yucatan. The models generally move the low pressure system northwestward over the southern Gulf of Mexico. However, there are fairly significant deviations in how far north the low moves once it is in the Gulf. As of 8:00 p.m. EDT on June 14 the National Hurricane Center was indicating that there was a 30% probability of the development of a tropical cyclone in this area during the next five days.
Some numerical models have also been suggesting potential development of a tropical cyclone near latitude 10°N over the tropical Atlantic Ocean between Africa and the Lesser Antilles. A tropical wave is interacting with the Intertropical Convergence Zone and there has been a persistent area of showers and thunderstorms. The disturbance is moving slowly toward the west. There is some vertical wind shear in this region, but the stronger upper level winds are north of the disturbance. The disturbance is over water where the Sea Surface Temperature is near 27°C. It would be unusual to see a tropical cyclone develop over the tropical Atlantic in June, but it has happened at least three times in the past. As of 8:00 p.m. EDT on June 14 the National Hurricane Center is indicating that there is a 20% probability of the development of a tropical cyclone in this region during the next five days.
A complicated disturbance over the northwestern Caribbean Sea is bringing squally weather to that area. A tropical wave over the western Caribbean Sea is interacting with an upper level low over eastern Mexico. The disturbance is causing thunderstorms over a region that extends from the northwestern Caribbean Sea to the southern Gulf of Mexico. Upper level divergence east of the upper low has led to the formation of a surface low pressure system east of Belize. At 7:00 p.m. EST on Thursday the center of the surface low was located at latitude 18°N and longitude 86°W which put it about 150 miles (240 km) east-southeast of Chetumal, Mexico. The surface low was moving toward the west-northwest at 10 m.p.h. (16 m.p.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 1011 mb.
The disturbance is not very well organized, which is normally the case when a tropical wave interacts with an upper level low. There is a broken area of thunderstorms that extends around the east and northern sides of the disturbance. However, there are not many thunderstorms close to the center of the surface low. The upper low is causing vertical wind shear over the western half of the surface low. Some upper level divergence is occurring over the eastern half of the surface low.
A large high pressure system over the western Atlantic Ocean is steering the disturbance toward the west-northwest. That general steering pattern is expected to continue for the next two days. On its anticipated track the disturbance will move over the Yucatan peninsula and over the southern Gulf of Mexico during the next several days.
The disturbance is in an environment that is marginally favorable for tropical development. The Sea Surface Temperature of the northwestern Caribbean is near 29°C. There is vertical wind shear, but it may be just small enough to allow for slow development. On the other hand, the disturbance will move over the Yucatan peninsula which will further inhibit development. There may also be a chance for development after the disturbance moves over the southern Gulf of Mexico. The National Hurricane Center is giving a 20% probability of tropical cyclone formation out of the disturbance.