[May 21] System in Western Caribbean Could Develop in Gulf of Mexico – More Rain for SE US

   Posted by Levi at 3:15pm on May 21, 2018

A strong upper trough reaching down into the Caribbean has spurred the development of a surface trough north of Honduras. Lots of wind shear and dry air are currently preventing development, but the disturbance will gradually track northward into the Gulf of Mexico by Thursday, and if it becomes vertically stacked beneath the upper trough, some subtropical or tropical development is possible. Models currently disagree on how far west or east the disturbance will track, with the GFS moving the system over the Florida Peninsula, and the ECMWF toward the central gulf coast. At this point, I would tend to lean toward the ECMWF track due to what appear to me to be convective feedback issues in the GFS. However, given the broad and disorganized nature of the system, there is a fair bit of uncertainty in its eventual track.

Regardless of the disturbance’s track, or even whether it develops, Florida will continue to receive periods of heavy rain throughout this week due to the tropical moisture flowing up the eastern side of the system, leading to potential flooding hazards. Considerable rain may fall along the central and eastern gulf coast states as well, especially late this week. The disturbance will move rather slowly on its way northward due to weak steering currents, leading to substantial accumulations. This rain is currently expected to be the primary impact from this system.

As of Monday evening, the NHC gives a 40% chance of subtropical or tropical cyclone formation during the next 5 days. Any development will be very gradual during the next 2-3 days while the system remains messy and sheared, and it is currently uncertain whether significant development will occur after midweek. Stay tuned to the National Hurricane Center and your local NWS office for the latest information.

Forecast Additional Rainfall for Next 5 Days:

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