Tropical Storm Ian churned through the central Caribbean on Saturday, beginning an ominous journey that could culminate in a collision with Florida on Thursday as a hurricane.
Uncertainty remains over exactly where in Florida Ian will strike, with a range of possibilities still on the table. There are some indications that it could make a more dramatic north and northeast turn before a landfall somewhere near Tampa, while other computer models simulate a northward movement and eventual stall before a landfall near the Panhandle.
The resulting forecast challenges mean it’s impossible to say how strong Ian will be when it makes landfall stateside, but the above-average warmth of ocean waters in the eastern Gulf of Mexico is a definite red flag for forecasters worried about a serious impact.
Florida Gov. Ron DeSantis (R) expanded his emergency order Saturday afternoon to cover the entire state. Late Saturday, President Biden approved an emergency declaration for Florida, which authorizes federal assistance and emergency measures.
“Ian is expected to remain a major hurricane when it moves generally northward across the eastern Gulf of Mexico during the middle of next week, but uncertainty in the track forecast is higher than usual,” the National Hurricane Center wrote. “Regardless of Ian’s exact track, there is a risk of dangerous storm surge, hurricane-force winds, and heavy rainfall along the west coast of Florida and the Florida Panhandle by the middle of next week.”
The storm is projected to come ashore in Florida on Thursday, although this timing could still shift.
According to the National Hurricane Center, the “earliest reasonable arrival time” of tropical storm-force winds would be Tuesday night in south Florida and Wednesday farther north.
What Ian is doing now
On Saturday at 8 p.m. Eastern time, Ian was 230 miles south of Kingstown, Jamaica, or about 430 miles southeast of Grand Cayman. It was moving westward at 14 mph. The Cayman Islands are under a hurricane warning.
Maximum sustained winds in the core of the storm were listed at 45 mph. On satellite, Ian can be seen roiling with one solid mass of convection, or downpour and thunderstorm activity, showing that it is beginning to consolidate and organize more.
On Friday, the surface circulation of Ian was visibly exposed east of the system’s clustering of thunderstorms, a sign of disruptive wind shear, or a change in wind speed and/or direction with height, knocking the entire system off-kilter. Since then, shear has begun to relax, meaning thunderstorms aren’t blown as far downwind of the surface vortex.
Rapid intensification en route to Cuba
Once shear is no longer an issue, there is little holding Ian back. It’s moving over water with temperatures approaching 90 degrees, meaning the seas are replete with thermal energy to fuel the storm.
There will also be an upper-level high-pressure system slipping overhead, which will help “vent” Ian and fan exhaust air away from the storm’s center. That will induce a vacuum-like effect in the upper atmosphere to enhance upward motion, intensifying the storm as more warm, moist air in contact with the ocean rushes into the circulation from below.
The National Hurricane Center is explicitly forecasting rapid intensification as Ian closes in on Cuba by Monday night, at which point the storm may be approaching major hurricane strength.
Major wild cards with forecast
It’s around Monday when weather models begin to markedly diverge from one another and the forecast becomes much more hazy. Part of that stems from where Ian is now. We can spot the system well on satellite, but we can’t “see” where its axis of rotation is from above, since it’s buried beneath thunderstorm anvils.
The storm’s course comes down to whether it is “captured” or scooped northeast by an approaching trough, or a dip in the jet stream that carries high-altitude cold air, low pressure and spin.
The European model is more optimistic on this northeastward tug toward Florida. In this model, Ian does link up with the trough, curving eastward more quickly and sweeping ashore toward the midcoast of Florida as a significant hurricane.
On the American GFS model, Ian “misses its ride” and is left to saunter north. By the time Ian actually makes it to the northern gulf on the GFS model, a wedge of dry air banked up works to cap its strength and even weaken it.
Irrespective of the storm’s exact path, officials stressed that this weekend is the right time for those potentially affected to start preparing.
“[R]esidents in Cuba, the Florida Keys, and the Florida peninsula should ensure they have their hurricane plan in place, follow any advice given by local officials, and closely monitor updates to the forecast,” the Hurricane Center advised.
Beyond Florida, Ian could also affect the Southeast and Mid-Atlantic as it is drawn northward toward the end of the week. However, how strong it will be and its path are still very uncertain.
Jason Samenow and Hamza Shaban contributed to this report.