Invest 91L Florida update, spaghetti models: Chances of weekend development dissipate

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A tropical wave over the Atlantic, formerly Invest 91L, is producing a limited amount of shower activity. Development is no longer expected, according to the latest advisory from the National Hurricane Center.

The tropical wave is expected to move westward at 10-15 mph and formation chances are at 0% over the next seven days, NHC forecasters said.

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The NHC is also monitoring a second tropical wave, this one in the Caribbean.

The next named storm of the Atlantic hurricane season will be Gabrielle.

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Here’s the latest advisory from the National Hurricane Center as of 8 p.m. Saturday, Sept. 6.

National Hurricane Center tracking tropical wave, formerly Invest 91L

A tropical wave over the central tropical Atlantic is producing a limited amount of shower activity. Development of this system is not expected while the system moves westward at 10 to 15 mph.

• Formation chance through 48 hours: low, 0 percent.

• Formation chance through 7 days: low, 0 percent.

Spaghetti models for tropical wave, formerly Invest 91L

Special note about spaghetti models: Illustrations include an array of forecast tools and models, and not all are created equal. The hurricane center uses only the top four or five highest performing models to help make its forecasts.

What other tropical waves, disturbances are in Atlantic basin?

Tropical wave 2: A central Caribbean tropical wave is along 72W from Hispaniola southward into NW Venezuela, moving W at around 10 kt. Scattered moderate convection is noted over Hispaniola.

What is an invest?

Short for investigation, the National Hurricane Center uses the term invest for areas of low pressure it is monitoring for potential development into a tropical depression or storm.

Invests are not tropical depressions or tropical storms. They’re usually clusters of showers and thunderstorms, and just because they’ve been designated as an invest does not guarantee they’ll strengthen into a tropical storm or hurricane.

Invests run from 90 to 99, followed by a letter: L for the Atlantic basin and E for those in the eastern Pacific. After 99, it starts over again and the next invest would be 90.

Once something has been designated as an invest, specialized data sets and computer models can begin, including scheduling Hurricane Hunter aircraft missions and running spaghetti models.

Is a hurricane coming toward Florida?

A tropical wave, formerly Invest 91L, is not expected to pose a threat to Florida or the U.S.

➤ September hurricane season forecast: Savor the break, but trouble is brewing in back half

When is tropical activity expected to increase?

“While there will be a relative lull in tropical activity during the first few days of September, atmospheric conditions will become a lot more conducive for development later this week and into next week,” said DaSilva.

More tropical waves are expected to move off the coast of Africa. With less dust and dry air in the way, it’s likely more of these waves will strengthen, according to AccuWeather.

Colorado State University predicting tropics to become more active

In its two-week forecast for Sept. 3-16, Colorado State University forecasters are predicting activity will pick up over the next couple of weeks.

“Global model ensembles are pretty aggressive with additional tropical cyclone development in days 8 through 14, with potential formations in the eastern Atlantic as well as in the western Caribbean/southern Gulf,” the CSU forecast said.

“The primary threat formation area for major hurricanes in early- to mid-September is in the eastern and central tropical Atlantic.”

What do the colored, hatched areas on the NOAA map mean?

The hatched areas on the National Hurricane Center’s tropical outlook map indicate “areas where a tropical cyclone — which could be a tropical depression, tropical storm or hurricane — could develop,” said National Hurricane Center Deputy Director Jamie Rhome.

The colors make it visibly clear how likely a system could develop, with yellow being low, orange medium, and red high.

The National Hurricane Center generally doesn’t issue tropical advisories until there is a named storm, but there is an exception.

“If a system is near land and there is potential for development, the National Hurricane Center won’t wait before it issues advisories, even if the system hasn’t become an actual storm. This gives residents time to prepare,” Rhome said.

What should be in a hurricane kit? Buy needed supplies tax free

Officials regularly encourage Florida residents to prepare for storms before a hurricane is approaching, while shelves are fully stocked and you aren’t battling crowds all rushing to the store at the same time.

“It only takes one storm to make it an impactful year for your community,” the National Hurricane Center Miami posted on X. “Hurricane season is a marathon, not a sprint.”

➤ See list of emergency supplies you can now buy tax free

On Aug. 1, specific hurricane supplies became permanently tax-free in Florida, ranging from batteries to generators.

➤ Don’t have a hurricane supply kit? From the basics to the extras, here’s what you need

Here are some of the basics you should have:

• Non-perishable food

• Two-week supply of medications

• Flashlight

• A go-bag with essential supplies in case you need to leave quickly

• Portable cellphone chargers

• Battery-operated radio

• List of emergency phone numbers, including those for family members

• Copy of your insurance policy

Florida live weather radar for Sept. 6, 2025

Florida weather watches and warnings

When is the Atlantic hurricane season?

The Atlantic hurricane season runs from June 1 through Nov. 30.

Ninety-seven percent of tropical cyclone activity occurs during this time period, NOAA said.

The Atlantic basin includes the northern Atlantic Ocean, Caribbean Sea and Gulf of America, as the Gulf of Mexico is now known in the U.S. per an order from President Trump. NOAA and the National Hurricane Center are now using Gulf of America on its maps and in its advisories.

When is the peak of hurricane season?

The peak of the season is Sept. 10, with the most activity happening between mid-August and mid-October, according to the Hurricane Center.

Hurricane names for 2025 season

Here are the names for the 2025 Atlantic hurricane season, along with how to pronounce them. The first hurricane of the season typically forms Aug. 11.

• Andrea  (June 20)

• Barry  (June 29)

• Chantal (July 5)

• Dexter: (Aug. 3)

• Erin: (Aug. 11; hurricane Aug. 15; major hurricane Aug. 16)

• Fernand: (Aug. 23)

• Gabrielle: ga-bree-ELL

• Humberto: oom-BAIR-toh

• Imelda: ee-MEHL-dah

• Jerry: JEHR-ee

• Karen: KAIR-ren

• Lorenzo: loh-REN-zoh

• Melissa: meh-LIH-suh

• Nestor: NES-tor

• Olga: OAL-guh

• Pablo: PAHB-lo

• Rebekah: reh-BEH-kuh

• Sebastien: se-BAS-tee-en

• Tanya: TAHN-yuh

• Wendy: WEN-dee

National Hurricane Center map: See what forecasters watching now

Systems currently being monitored by the National Hurricane Center include:

Why does NHC say ‘tropical cyclone’ on its maps instead of hurricane or tropical storm?

Tropical cyclone is the generic term used by the National Weather Service, NOAA and the National Hurricane Center for any tropical system, even if it’s in the tropical Atlantic basin.

To be more precise, a tropical cyclone is a “rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation,” NOAA sadi.

Once maximum sustained winds reach 74 mph, what it is called is determined by where it originated:

• Hurricane: for storms in the North Atlantic, central North Pacific, and eastern North Pacific.

• Typhoon: for storms in the Northwest Pacific.

• Cyclone: for storms in the South Pacific and Indian Ocean.

Interactive map: Hurricanes, tropical storms that have passed near your city

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This story has been updated to include new information.

This article originally appeared on Sarasota Herald-Tribune: Tropics forecast: Invest 91L path, track, timeline. Florida impact?