A strengthening tropical storm is expected to become Hurricane Isaias this week, threatening to batter parts of the southern United States with heavy rain and strong winds.
Tropical Storm Nine had sustained winds of 35 mph and was located about 900 miles south of the mouth of the Mississippi River as of Tuesday evening.
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The system is expected to move east over the Yucatan Peninsula, then turn sharply north toward the northern Gulf Coast. It is expected to rapidly strengthen and become a Category 2 hurricane with winds of 160 mph by Friday.
Isaias could bring heavy rain, strong winds and storm surge to areas from southern Louisiana to the Florida Panhandle starting Friday. This storm could also cause a rain band to hit the coast and some tornadoes.
This will be the first hurricane of the year in the Atlantic Basin and likely end the record-long wait associated with the strongest El Niño on record.
It’s still unclear where exactly the storm will track or how strong it will be as it approaches land, but those along the Gulf Coast from Louisiana to Florida’s Big Bend should keep a close eye on the forecast.
Florida Gov. Ron DeSantis on Tuesday declared a state of emergency in 25 counties ahead of the storm and urged residents to prepare disaster plans and stock up on hurricane supply kits. State emergency teams are deploying generators, fuel, food, water and flood barriers to the Tallahassee and Santa Rosa areas to aid in the response.
Oil companies are also taking precautions in the Gulf region. Shell has evacuated non-essential personnel from six offshore platforms, while BP has removed non-essential employees to ensure the safety of its offshore facilities, the companies announced on Tuesday.
The storm is pushing through the El Niño-influenced atmospheric conditions that have had a major impact on tropical systems throughout the Atlantic hurricane season thus far. Gulf waters are warmer on record for this time of year and fuel is plentiful, but that’s only part of the equation.
The problem with tropical Atlantic systems this season is wind shear. This refers to winds that blow at different speeds and from different directions at several levels of the atmosphere. Wind shear can tear apart tropical storms and hurricanes.
This new system benefits from low wind shear in the southern Gulf Coast, but protecting the northern Gulf Coast will generate higher wind shear that threatens to tear apart storms as they approach.
However, this system is also predicted to move rapidly, so the impact on higher wind shear may be limited. As the storm moves slower, it can weaken quickly, meandering through severe conditions.
The strength and path of the storm are also intertwined. Stronger storm circulations can extend higher up in the atmosphere and direct storms in different directions than systems with weaker winds at that height. Its path, in turn, determines how long it spends over warm water and how much hostile wind shear it encounters, shaping its strength when it reaches the shore.
Regardless of its ultimate fate, heavy rain is expected to hit the Gulf Coast and other parts of the South by later this week. The storm could dump 3 to 6 inches of rain locally from southern Louisiana to the Florida Panhandle and Big Bend, with locally up to 10 inches possible. Heavy rain could begin to intensify along the coast as early as Friday and continue to soak areas as it spreads further inland into the weekend.
As has already been shown this year, hurricane-strength systems do not cause significant impacts, especially in a warming world where tropical systems are becoming wetter.
Tropical storms Arthur and Edouard did not last long, but heavy rains caused massive flash flooding and water rescues. Parts of Louisiana and Mississippi bore the brunt of Arthur’s flooding, with Edouard dumping more than 20 inches of rain in eastern Texas.
Determining the location and severity of storm surge flooding, high winds, and tornadoes along the northern Gulf Coast is even more difficult at such a remote point because it requires knowing the strength and exact location of the storm. The earliest these effects could arrive is Friday or late Saturday.
Typical situation in October and November
Four named storms of tropical storm strength or higher typically occur in October and November, but can end stronger or quieter depending on the hurricane season.
The past few years have shown this year-to-year ebb and flow. Seven storms occurred between October and November in 2024, while only two storms occurred during the same period in 2023.
Late-season storms tend to form in areas closer to the United States, such as the Gulf, Caribbean, and off the south-south coasts, and are more likely to impact land.
There are usually fewer storms, but destructive ones can still occur.
Last year, Category 5 Hurricane Melissa devastated Jamaica in the last week of October.
Hurricane Michael roared into the Florida Panhandle on October 10, 2018, becoming the most recent Category 5 to make landfall in the United States on record. And Hurricane Sandy may be the most infamous of all hurricanes. In late October 2012, it transformed into a hybrid superstorm and hit the East Coast.
The notorious late-season hurricanes are unlikely to form again this year as Super El Niño continues to batter the Atlantic Basin. For the first time this season, the reliable record shows that the main reason we haven’t seen a hurricane is the winds that drive the storm.
