Tropical Storm Ian expected to threaten Florida as major hurricane next week

Tropical Storm Ian formed Friday in the Caribbean Sea, and much of the Florida Peninsula is already included in the cone of uncertainty for what could become a major hurricane in the days ahead.

The tropical storm joins three other systems currently roaming the Atlantic basin, including post-tropical cyclone Fiona, which is impacting Canada, Tropical Storm Gaston near the Azores and Tropical Storm Hermine over the far eastern Atlantic.

Here's everything the FOX Forecast Center knows about this significant threat to the southeastern U.S. next week.

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Where is Tropical Storm Ian?

As of Saturday morning, Tropical Storm Ian was in the central Caribbean Sea and centered about 300 miles southeast of Kingston, Jamaica, and about 570 miles away from the Cayman Islands.

The tropical storm had maximum sustained winds of about 45 mph and was moving west-southwest at 15 mph.

The Hurricane Hunters have several missions scheduled for Tropical Storm Ian to collect data that will be used to help meteorologists refine their forecasts.

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Who is under watches and warnings?

A Hurricane Watch has been issued for the Cayman Islands and a Tropical Storm Watch was in effect for Jamaica. 

A Hurricane Watch means that hurricane conditions are possible within the alerted area. A watch is typically issued 48 hours before the anticipated first occurrence of dangerous winds.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

What is the forecast for Tropical Storm Ian?

The cyclone is only expected to slowly strengthen over the next 24 hours and more significant intensification could begin on Monday.

The latest NHC shows the system becoming a hurricane in the northwestern Caribbean Sea on Monday as it nears the Cayman Islands. 

By the start of the workweek, the future-hurricane is expected to be located somewhere between the eastern Gulf of Mexico and the general vicinity of the Florida Peninsula, possibly with winds greater than 115 mph.

This would make Ian a Category 3 or stronger on the Saffir-Simpson Hurricane Wind Scale.

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"Now what you want to focus on is how big the cone really is. The skinnier the cone, the more confidence in the forecast. The larger the cone, the more questions there are as to where this storm is going to go," FOX Weather meteorologist Britta Merwin explained. "Obviously, on days 4 and 5 as it gets closer to Cuba and Florida, you see more of a spread, and that's something to really take note of. There are a lot of changes that are likely to happen in the later half of this forecast, and this entire area really needs to look out for the potential of where we could be seeing this system as we get into early next week."

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The tropical storm is still battling wind shear – winds that change direction and speed at various heights – which is keeping thunderstorms associated with the system from rapidly organizing.

According to the FOX Forecast Center, Tropical Storm Ian is expected to move into an area of the Caribbean Sea containing much lower wind shear and an abundant supply of deep, warm waters over the weekend.

WHAT IS WIND SHEAR?

Water temperatures in this part of the Caribbean Sea are in the upper 80s, which is a couple of degrees above average, providing ample fuel for this system to intensify over the coming days.

However, one inhibiting factor could be land interaction with Cuba early next week before it reaches the Gulf of Mexico toward the middle of the week

What are the expected impacts of Tropical Storm Ian in the Caribbean?

The main concern from Tropical Storm Ian is heavy rainfall for Jamaica, the Cayman Islands, western and central Cuba, southern Haiti and the southern Dominican Republic beginning as soon as this weekend, according to the FOX Forecast Center.

The highest rainfall amounts are predicted in western and central Cuba, where 6 to 10 inches is expected with isolated amounts up to 14 inches. Jamaica and the Cayman Islands could see 4 to 8 inches of rain, with localized amounts up to 12 inches.

In southern Haiti and the southern Dominican Republic, between 2 and 4 inches of rain is forecast, though locally higher totals as high as 6 inches are possible.

Depending on the exact track and intensity of Tropical Depression Nine, there could also be tropical-storm-force (39-plus mph) or hurricane-force (74-plus mph) winds in these areas.

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What threat will Tropical Storm Ian pose to Florida and the US Gulf Coast?

Tropical Storm Ian is predicted to be steered in the general direction of the eastern Gulf of Mexico and could be near the Florida Peninsula by the middle of next week.

An overwhelming majority of computer forecast models suggest the storm will likely be a major hurricane as it tracks toward the mainland U.S.

Each yellow line on the map depicts a different computer forecast model solution.

However, forecasts for newly developed tropical cyclones are challenging, so don't be surprised if the forecast for Tropical Storm Ian undergoes several changes – some of which could be significant – over the coming days.

The storm-track guidance from the various computer forecast models currently ranges from the eastern Gulf of Mexico to near or off Florida's Atlantic coast, so everyone in this general zone should begin their preparations now in the event of a potential major-hurricane strike next week.

HOW TO PREPARE FOR A HURRICANE

So the bottom line is that it's still too early to know exactly where this system is heading, but know that there is a growing threat of a major hurricane impacting the southeastern U.S. around the middle of next week.

Florida Gov. Ron DeSantis declared a state of emergency for 24 counties that may be in the eventual path of Tropical Storm Ian, saying Floridians should prepare for the coming storm now. Residents can check their evacuation zone by typing in their address into an interactive map.

The FOX Forecast Center will be keeping a close eye on this system as it strengthens and tracks across the Caribbean in the days ahead.