For at least a week, computer models have consistently shown the development of a tropical cyclone in the western Caribbean Sea or eastern Gulf of Mexico this weekend. This potential cyclone is likely to cross the Florida peninsula early next week, where it may unload very heavy rainfall.

Assuming this system reaches tropical storm intensity and is named, it would be Colin, and would be the earliest third tropical storm on record in the Atlantic by about a week.


Enhanced infrared satellite image over the western Caribbean Sea from 9:45 a.m. Eastern today. (NASA)

Although there is not a low pressure associated with this festering blob yet, one is expected to form this weekend as it drifts to the northwest. Global models generally show something coherent forming near the Yucatán Peninsula on Sunday, then moving north and turning to the Florida peninsula on Monday.

The National Hurricane Center is giving this disturbance a 10 percent chance of formation within the next two days, and a 60 percent chance of formation within the next five days.

There is good agreement on the future track of this potential tropical cyclone. This example, from the GFS model ensemble, shows all 20 simulations forming a cyclone in roughly the same location and tracking over the Florida peninsula.


GFS ensemble formation probability and cyclone tracks over the next five days. (NOAA)

As with any tropical system, there is the potential for very high rainfall amounts and flooding. The National Weather Service’s morning forecast for the next five days shows almost all of Florida predicted to receive at least two inches of rain, and central Florida more than five inches. Local areas could certainly receive more than this.


Forecast of total rainfall amounts through Wednesday morning. (NOAA)

It is too early to talk about intensity at landfall, but the stronger it is, the greater the risk of storm surge along the southwestern coast of the peninsula. Even a couple of feet coupled with a regular high tide can be troublesome for some areas.

The ocean temperatures are very warm in the western Caribbean, and sufficiently warm in the eastern Gulf to sustain development, so the limiting factors for intensification will be proximity to land masses and vertical wind shear. As it gains latitude, it should begin to interact with a trough to the north, which will make it very difficult for this system to become any stronger than a tropical storm.

Recent map of sea surface temperatures in the area of interest. (UMiami)
Recent map of sea surface temperatures in the area of interest.  Anything over about 26°C can sustain tropical cyclones. (UMiami)

The impacts from the system on Florida would most likely begin on Monday and last into Tuesday.