Potential Tropical Cyclone 16 Is Expected to Become Nestor & Will Bring Rain, Wind, Storm Surge to Parts of Gulf Coast

weather.com meteorologists
Published: October 18, 2019

A tropical or subtropical storm, dubbed Potential Tropical Cyclone 16 by the National Hurricane Center, is likely to form in the Gulf of Mexico Friday and will bring soaking rain, winds and coastal flooding to parts of the Southeast this weekend.

(MORE: What Is a Potential Tropical Cyclone?

Right now, this disturbance is centered over the central Gulf of Mexico. The system is strengthening and gradually organizing and is expected to gain at least some tropical cyclone characteristics.

Gulf Development Chance

Potential Tropical Cyclone 16 will be designated a tropical or subtropical depression or storm once it has a complete, counterclockwise surface circulation with organized thunderstorms nearby. As of late Friday morning the National Hurricane Center says the circulation is still quiet elongated and not well defined.

If it becomes a tropical/subtropical storm, it would be called Nestor.

(MET 101: What is a Subtropical Cyclone)


Current Storm Status

A tropical storm warning has been issued for parts of the northern Gulf Coast from the Mississippi/Alabama border to Yankeetown, Florida, and from Grand Isle, Louisiana, to the mouth of the Pearl River.

A tropical storm warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.


Watches and Warnings

A storm surge warning has also been issued from Indian Pass, Florida, to Clearwater Beach, Florida. A storm surge warning means that there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours.

Regardless of what meteorologists call it, this system is expected to move northeastward over the Gulf of Mexico and into the Southeast relatively quickly.

This system will produce much of its worst weather ahead and to the right of its center, and well outside of the cone of uncertainty shown below.


Projected Path

The system may strengthen a little more as water temperatures remain unusually warm in the Gulf of Mexico, but increasing upper-level winds over the northern Gulf of Mexico, which will help it move swiftly toward the northern Gulf Coast, should also produce wind shear, typically a strike against significant intensification of tropical cyclones.

(MORE: Deeper Dive into the Gulf System


Satellite and Wind Shear Analysis

Potential Impacts

Wind, waves and coastal flood/surge impacts depend on the size and strength of the Gulf system, which remains somewhat uncertain given the system hasn't formed in the Gulf, yet.

Storm Surge, Coastal Flooding

South to southwest winds ahead of the system blowing over a long fetch of the Gulf of Mexico may generate swells that may reach the northern and eastern Gulf Coasts as soon as Friday.

These swells could generate high surf and rip currents and could persist through Saturday.

The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline.

Water could reach the following heights above ground if the peak surge occurs at the time of high tide:

-3 to 5 feet from Indian Pass, Florida, to Chassahowitzka, Florida

-2 to 4 feet from Chassahowitzka, Florida, to Clearwater Beach, Florida


Storm Surge Forecast

Wind

Tropical storm force winds are expected to first reach the coast within the warning area by late Friday or early Saturday, making outside preparations difficult or dangerous.


Probability and Arrival of Tropical Storm Winds

Gusty winds will spread inland across the Southeast through Saturday with localized gusts over 40 mph possible at times, especially near the Gulf Coast.


Wind Forecast

Tornadoes

A few severe thunderstorms, including the risk of tornadoes, are possible in parts of the Southeast on Friday and Saturday, especially across northern and central Florida.

(MORE: Tornadoes Possible With Future-Nestor Along Gulf Coast


Thunderstorm Outlook

Rainfall

This system's relatively fast movement should keep it from becoming a major, widespread rainfall flood concern. Remember, a tropical storm or hurricane's rainfall potential largely depends on how fast it moves, not how strong it becomes.

Rain and thunderstorms are expected to arrive along parts of the northern and eastern Gulf Coasts Friday.

This rain could become heavy Friday night into Saturday generally along, and to the northeast of, the track of the Gulf system, and may linger in some parts of the Southeast into Sunday.

The National Hurricane Center expects rainfall accumulations of 2 to 4 inches from the central Gulf Coast and northern and central Florida into the eastern Carolinas, with isolated areas receiving up to 6 inches.


Forecast Rainfall Through Sunday

Overall, this rain could be beneficial, given the flash drought that has developed over the Southeast.

This system may then move along the mid-Atlantic coast and may bring rain to the mid-Atlantic and Northeast coast into Sunday night.

Western Gulf Development Unusual This Late

Tropical development in the western Gulf of Mexico is certainly not unusual in hurricane season.

It is quite rare this late in the season, though.

Only seven named storms since 1960 have formed in the western Gulf of Mexico after October 1, according to Brian McNoldy, tropical scientist at the University of Miami.

One of those storms, Tropical Storm Josephine, came ashore in Apalachee Bay, Florida, on Oct. 7, 1996, with maximum winds of 70 mph, just a notch below hurricane status.

Josephine's most notable impact was storm surge. Storm tides of up to 9 feet were reported in Levy County, Florida. Pinellas and Hillsborough Counties – the Tampa-St. Pete metro area – reported storm tides of 4 to 6 feet that flooded roads and buildings, according to the National Hurricane Center's report on Josephine.

October tropical storms and hurricanes most often develop in either the western Caribbean Sea, eastern Gulf of Mexico, or off the U.S. East Coast in the western Atlantic Ocean.

(MORE: Hurricane Season is Far From Over)

This system originated from a large low-pressure area known as a Central American gyre (CAG).

This large low-pressure area typically forms both in late spring and early fall. It can spawn tropical storms and hurricanes in both the Atlantic and Eastern Pacific Basins, sometimes in each basin at the same time.

Roughly 50 percent of Central American gyres have a tropical cyclone associated with them, according to Philippe Papin, research scientist at the U.S. Naval Research Laboratory and expert on CAGs. "When a tropical cyclone does occur, it tends to form on the eastern side of the [gyre] and rotates counterclockwise around the larger circulation," Papin told weather.com.

In recent years, the Central American gyre has spun off some notable storms.

In October 2018, what eventually became Hurricane Michael was spun off the east side of a CAG and was only the fourth mainland U.S. Category 5 landfall.

One year before that, Hurricane Nate also formed along the eastern edge of a CAG and came ashore along the northern Gulf Coast in October 2017. Nate's deadliest impacts were in Central America, where widespread flooding and mudslides claimed 44 lives.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.


The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.