Hurricane

Newly formed tropical depression 18 set to become Category 3 Hurricane Sam by Sunday

Tropical depression 18 has formed in the Eastern Atlantic, and the National Hurricane Center’s forecast shows it becoming a Category 3 hurricane by early next week as it edges closer to the Caribbean.

As of the 5 p.m. update, the system was more than 2,000 miles east of the Northern Leeward Islands and headed west at 15 mph. It was packing 35 mph sustained winds but is expected to strengthen in the coming days.

Forecasters said the depression is likely to become Tropical Storm Sam in the next 12 hours and hit hurricane status by early Saturday. By Monday, the hurricane center predicted Sam will be a Category 3 with 115 mph maximum winds.

According to the forecast discussion, a ridge to the north and west of the system should steer it straight west for the next few days along a path of warm ocean water and low wind shear — “quite favorable” conditions for intensification.

As of the latest forecast, tropical depression 18 had a broad but defined center in lower-level winds, forecasters said. If mid-level winds match up soon, the system could strengthen quickly in the next five days.

Tropical Depression 18 has formed in the Atlantic, and it’s set to become Catgeory 3 Hurricane Sam this week.
Tropical Depression 18 has formed in the Atlantic, and it’s set to become Catgeory 3 Hurricane Sam this week. NHC

Hurricane models all seem to agree on what the system will do in the next three days — head straight west and strengthen — but beyond that, the spread of possible next steps gets less clear. Most models appear to show the hurricane curving north, up and away from the Caribbean and into the open sea.

With the formation of Tropical Depression 18, 2021 is now neck-and-neck with 2020 for the record of most storms formed before September 23, tweeted Colorado State University Meteorologist Phil Klotzbach.

Peter

As for Tropical Depression Peter, the poorly organized storm was about 225 miles north-northwest of San Juan, Puerto Rico, with maximum sustained winds near 35 mph with higher gusts, as of the hurricane center’s 2 p.m. advisory Wednesday.

It is expected to cause some urban and small street flooding across Hispaniola, Puerto Rico and portions of the Virgin Islands through Thursday morning, forecasters said. Life-threatening surf and rip current conditions are also possible in the area Wednesday, including in the Bahamas.

On the forecast track, Peter should turn north Wednesday night, moving it farther from Puerto Rico and the Virgin Islands. Forecasters expect it will continue to weaken and eventually turn into a remnant low Thursday, if not sooner.

Rose

Disorganized Tropical Depression Rose, which was about 1,065 miles west-northwest of the Cabo Verde Islands with maximum sustained winds near 35 mph with higher gusts, has a similar forecast. It’s expected to make a turn toward the north Thursday and should weaken into a remnant low by Friday night.

Odette

Tropical Storm Odette’s remnants are also still making a loop in the Atlantic, about 500 miles west of the Azores. While it had a 60% chance of formation through the next five days, forecasters expect the system will run into some strong upper-level winds by the weekend.

This story was originally published September 22, 2021 at 7:13 AM.

Alex Harris
Miami Herald
Alex Harris is the lead climate change reporter for the Miami Herald’s climate team, which covers how South Florida communities are adapting to the warming world. Her beat also includes environmental issues and hurricanes. She attended the University of Florida.
Michelle Marchante
Miami Herald
Michelle Marchante covers the pulse of healthcare in South Florida and also the City of Coral Gables. Before that, she covered the COVID-19 pandemic, hurricanes, crime, education, entertainment and other topics in South Florida for the Herald as a breaking news reporter. She recently won first place in the health reporting category in the 2025 Sunshine State Awards for her coverage of Steward Health’s bankruptcy. An investigative series about the abrupt closure of a Miami heart transplant program led Michelle and her colleagues to be recognized as finalists in two 2024 Florida Sunshine State Award categories. She also won second place in the 73rd annual Green Eyeshade Awards for her consumer-focused healthcare stories and was part of the team of reporters who won a 2022 Pulitzer Prize for the Miami Herald’s breaking news coverage of the Surfside building collapse. Michelle graduated with honors from Florida International University and was a 2025 National Press Foundation Covering Workplace Mental Health fellow and a 2020-2021 Poynter-Koch Media & Journalism fellow.  Support my work with a digital subscription
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