At a Glance

T.D. 28 will bring heavy rain to parts of Cuba, the Cayman Is. and The Yucatan Peninsula. It could move into the Gulf of Mexico as a tropical storm.The system may become the season's next hurricane, but will weaken before reaching the U.S.

Tropical Depression Twenty-Eight has formed in the northwestern Caribbean Sea and is expected to be a rainfall threat to the Gulf Coast next week.

Tropical storm warnings have been issued for the western tip of Cuba, where tropical storm conditions are expected on Monday.

Tropical storm watches have been issued for the northeastern portion of Mexico's Yucatan Peninsula and for Cozumel, where tropical storm conditions are possible late Monday into early Tuesday.

The center of newly-formed T.D. 28 is located just west of the Cayman Islands with little motion since it formed Saturday evening. Showers and thunderstorms are spreading through the western Caribbean Sea and into the southeastern Gulf of Mexico.

The Latest

(The red-shaded area denotes the potential path of the center of the tropical cyclone. It's important to note that impacts (particularly heavy rain, high surf, coastal flooding, winds) with any tropical cyclone usually spread beyond its forecast path.)

When it becomes a tropical storm, it would be called Zeta, the 27th named storm of the season.

The system has several aspects working in its favor for development.

It's located over an area with the warmest water anywhere in the Atlantic Basin, with surface temperatures 84 to 86 degrees Fahrenheit. This provides heat and moisture to a developing system and helps keep the air unstable enough for thunderstorms to redevelop.

Current Water Temperatures

(The location of the tropical disturbance is shown by the "L" icon. )

Secondly, winds aloft are spreading apart away from the system – meteorologists call it divergence – encouraging air to rise, supporting instead of suppressing thunderstorms.

Finally, this is an area still , as discussed in an article earlier this month.

Outlook

This system probably will be a slow-mover, at least initially. It's generally expected to drift to the northwest over the next few days, eventually entering the Gulf of Mexico by Tuesday, possibly as a hurricane.

If interaction with western Cuba or Mexico's Yucatan Peninsula occurs, the system will remain weaker until it can return to water.

Ensemble Model Forecast Tracks

(These are forecast tracks from the GEFS showing possible tracks of the tropical system over the next 5 days. None of these is considered an official forecast, which comes from the National Hurricane Center once a tropical depression or storm forms. This is meant to show uncertainty in the forecast track, which is typically higher for weaker or incipient systems and for slow-moving or stalled systems.)

Intensification is expected through roughly Tuesday night over the warm Caribbean and Gulf of Mexico waters.

Then, it gets more complicated.

Westerly winds aloft are blowing over the Gulf of Mexico, Florida and the Bahamas. These winds are providing wind shear – the change in wind speed and/or direction with height – that is usually hostile to developing and mature tropical cyclones.

Forecast Wind Shear

(Areas of strong wind shear, the difference in wind speed and direction with height, are shown in purple. High wind shear is hostile to mature tropical cyclones and those trying to develop. The future position of the tropical system is also plotted.)

Too much shear and the system could be ripped apart or at least weaken before reaching the northern Gulf Coast. If wind shear is less or upper-level winds act to ventilate the system, it could grow stronger.

For now, interests along the Gulf Coast, Cuba, the Cayman Islands and Mexico's Yucatan Peninsula should monitor the progress of this system.

This may become a storm surge and damaging wind threat for the U.S. Gulf Coast as well.

Regardless of development, given the system's initial slow movement, locally heavy rain and flash flooding are possible the next several days from the Cayman Islands and Jamaica into Cuba, parts of the Florida Peninsula and the Yucatan Peninsula.

These locations should expect 4-8 inches of rainfall with localized amounts up to a foot of rain.

Season Status

As mentioned earlier, the next Atlantic Basin tropical storm will be named Zeta.

We've used 26 storm names this season, including several from the overflow Greek alphabet, which is being used for additional named storms for only the second time.

The used up the first six letters of the Greek alphabet, but it took until the end of December for Zeta to form that year.

(MORE: Strangest Moments of the Hurricane Season, So Far)

Greek names used in the 2020 Atlantic hurricane season through Epsilon. Names grayed out were not used in the record 2005 Atlantic hurricane season.

One unnamed subtropical storm was found in post-analysis of the 2005 season, thus bringing that season's record total to 28 storms.

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