A tropical disturbance in the Caribbean is likely to become a hurricane by midweek as it moves over Cuba into the Gulf of Mexico, federal forecasts said Sunday.

Residents of the west coast of Florida and other Gulf Coast states should monitor developments and expect at least heavy rain later in the week, the National Hurricane Center said in a series of updates and forecast calls.

Potential Tropical Cyclone 18 is located about 345 miles south of Kingston, Jamaica, the hurricane center said in an update at 7 p.m., and is moving northeast at 7 miles per hour. Sustained wind speeds of 35 miles per hour were recorded, it said.

The US Air Force's 53rd Weather Reconnaissance Squadron, which uses Super Hercules fixed-wing aircraft, took a close look at it on Sunday, the hurricane center said in an afternoon forecast briefing.

“Your data indicates that the system has developed a closed center,” it said, indicating that the storm is forming.

Still, the upward movement of warm air and precipitation was not intense enough to designate the disturbance as a tropical depression, the hurricane center said. It would probably come overnight, they said.

Hurricane formation likely

Meteorologists at the hurricane center said there was a 100 percent chance that the disturbance would at least develop into a tropical depression and a 100 percent chance that it would then strengthen later in the week.

The maximum wind speed for a tropical depression is 38 miles per hour. It is developing into a tropical storm at 39 miles per hour and could hit early Tuesday, according to forecasts from the hurricane center.

The system was likely to become a hurricane by early Tuesday afternoon, requiring sustained winds of at least 75 mph (120 km/h), and will remain so as it reaches Cuba on Tuesday or Wednesday, the center said.

But its strengthening could pause as it reaches the Gulf of Mexico, where drier air would counteract it, the center said.

“The intrusion of dry air should end the strengthening process and likely lead to some weakening,” an afternoon forecast discussion said.

By the time it reaches the northern Gulf Coast, it may have weakened to a tropical storm, the center said, noting that there are uncertainties in the long-term forecast.

If the system develops into a hurricane, it will be the 11th of the 2024 Atlantic season, University of Colorado meteorologist Philip Klotzbach said on X. Names available for the system include Rafael and Sara, according to the hurricane center.

Danger of storms

Meanwhile, the hurricane center said hurricane conditions were possible in the Cayman Islands within 48 hours. A tropical storm warning was in effect for Jamaica, meaning winds of 39-73 miles per hour are expected in 24 to 36 hours.

The northward-moving storm was expected to move near Jamaica on Monday and near the Cayman Islands on Tuesday, federal forecasts said. There could be coastal flooding from a storm surge and heavy rainfall of up to 9 inches, they said.

There will also be heavy surf in the western Caribbean at least until midweek, forecasters said.

Warm water as fuel

U.S. forecasters expect it to shift its north-northeast movement to the north-northwest and enter the Gulf of Mexico through the Yucatán Channel before moving toward the Gulf Coast later in the week.

It's still uncertain where potential Tropical Cyclone 18 would head in the Gulf, which has experienced extreme average sea surface temperatures that peaked at about 88 degrees in August and remains warm at about 75 degrees this month.

Experts at the National Oceanic and Atmospheric Administration say storms prefer sea surface temperatures of at least 80 degrees to develop into hurricanes.

Tropical cyclones are powered by warm seawater, which promotes the vertical movement of warm air, which helps the storms spin counterclockwise as they spew rain and wind.

“When the surface water is warm, the storm absorbs thermal energy from the water, just like a straw absorbs a liquid,” says a NOAA video about tropical storm formation.

According to data shared by Kim Wood, a professor of atmospheric sciences at the University of Arizona, on the social media platform

This could help explain the rapid development and intensity of some of the season's storms, including Hurricane Milton in October, which developed from a named storm to a hurricane within 24 hours, according to NOAA.

“This explosive amplification was fueled in part by record to near-record temperatures in the Gulf of Mexico,” it said.

The warmer-than-average water is an indication of climate change and could help trigger more intense and faster-developing storms, experts from NOAA and the U.S. Environmental Protection Agency said.