Low-level winds swirling around a developing low-pressure system, centered over the Florida panhandle on Tuesday morning. (earth.nullschool.net)

A low-pressure system over the Florida panhandle will move out over warm Gulf of Mexico water late Tuesday and is expected to become the season’s second tropical cyclone later this week.

The National Hurricane Center and computer models predict a tropical depression or storm will probably form (the Hurricane Center says there is an 80 percent chance) as early as Wednesday. If it does reach tropical storm intensity, it will be named Barry.

Although odds favor storm development over the Gulf of Mexico, there is a small chance the disturbance remains disorganized and never earns a name. Even if it doesn’t become a depression or storm, one thing is certain: It will rain along the Gulf Coast. A lot.

As of now, very hefty rainfall totals are forecast along the northern Gulf Coast, and inland throughout Mississippi and especially over Louisiana and eastern Texas. Amounts of at least five inches may be widespread, and more than 10 inches could fall in some areas.

Seven-day accumulated rainfall forecast. (NOAA/WPC)

While the two leading computer models, the American and European, generally agree a tropical cyclone will form and make landfall between western Louisiana and eastern Texas on Saturday, the American model predicts a much weaker tropical cyclone.

The stark difference in the models’ intensity forecast is illustrated below. The American (GFS) model (left) only simulates the formation of a tropical depression (with maximum sustained winds below 39 mph) but the European (right) forecasts a Category 1 hurricane.

Comparison of forecast low-level winds and surface pressure from the GFS, left, and ECMWF models, valid on Saturday evening. (tropicaltidbits.com)

Both model scenarios would bring substantial rainfall in affected areas, while the European model’s prediction would introduce wind and storm surge hazards. Storm surge refers to the rise in water above normally dry land generated at the coast, which can inundate low-lying areas.

Anyone along the Gulf Coast between the Florida Panhandle and Texas should be paying especially close attention as this forecast evolves.

Climatologically, the second named storm forms Aug. 1, so if Barry forms it will be ahead of schedule. But if you recall, Andrea was a subtropical storm that lasted less than a day at the end of May.

The map below shows the tracks of the 20 previous named storms that formed in the Gulf of Mexico during July since 1900.

Tracks of the 20 named storms that formed in the Gulf of Mexico during July since 1900. The 1943 "Surprise Hurricane" is highlighted. (Brian McNoldy)

The strongest one occurred in 1943, and is curiously similar to this current system. Dubbed the “Surprise Hurricane,” it had its origins as a low-pressure system inland over the southeast United States, drifted out over the northeast Gulf of Mexico, then became a tropical storm as it traveled west. It intensified to a Category 2 hurricane and became part of hurricane history when the first-ever aircraft reconnaissance flight into a hurricane took place. It made landfall in the Houston area shortly after the flight.