Day for decisions: South Florida officials ready for Ian

Latest update on the tropics provided by Local 10 Hurricane Specialist and Storm Surge Expert Michael Lowry

The sun rises over newly formed Tropical Storm Ian in the central Caribbean. (NOAA)

Tropical Storm Ian – upgraded late Friday night from Tropical Depression Nine – is still in its formative stages but gradually organizing in the central Caribbean as South Florida officials ready for what they’re calling a “day for decisions” ahead of a still-erratic track forecast for a potentially significant and major hurricane threat next week.


The picture beyond this weekend hasn’t become clearer over the past 24 hours, with the possibility of a future Hurricane Ian threatening anywhere from the northern Gulf Coast and Florida panhandle to the Florida Keys.

If the threat materializes over South Florida, however, tropical storm winds (winds greater than 38 mph) may arrive as early as Tuesday.

So regardless of the future track possibilities, South Floridians should prepare this weekend for a possible hurricane strike and be ready to finalize any necessary actions by Monday.

Emergency managers in Monroe County and the Keys will be discussing evacuations and sheltering of visitors and high-risk communities Saturday morning, so expect guidance later Saturday and Sunday from local officials.

Part of the challenge plaguing forecasts for next week is the nascent center of Ian which is still taking shape.

The storm has turned from west-northwest Friday night to west-southwest Saturday morning. While we anticipated a brief turn westward, the southwesterly jog may indicate a competition ongoing between Ian’s mid-level center being blown southwestward by persistent wind shear and its formative low-level circulation chasing it.

The small differences now matter in the long run for us in South Florida, as how far south or north the center gets will influence when and where it eventually turns. The uneven distribution of thunderstorm activity south of the center could work to tug the system farther south and west in the short term.

There was a clear shift westward overnight in forecast models, but it’s a little too soon to call it a trend.

Overnight global forecast models and their ensembles for Tropical Storm Ian through next Wednesday morning. The blue ellipse indicates the large spread, especially among ensembles which vary the starting position of the storm. (Tomer Burg/University of Oklahoma.)

Bottom line: South Florida’s squarely in the threat zone, but the track is by no means locked in.

Typically we have more confidence in track forecasts than intensity forecasts, but in Ian’s case, we fully expect a strengthening hurricane – perhaps a rapidly strengthening hurricane – as it approaches the western Caribbean by late Sunday into Monday. Ian may move over western Cuba early next week, but the land interaction will be brief and isn’t expected to appreciably affect its strengthening. The intensity forecast calls for a major Category 3 hurricane on approach to the U.S. next week.

We’re in the middle innings of this one, so a lot can change with the forecast.

The average forecast track error out four or five days is hundreds of miles, so with higher-than-average uncertainty, we can expect changes.

The game plan for South Floridians doesn’t change, however. Button up your family preps Saturday and Sunday and be ready to act if necessary.

We’ll keep you posted on all the forecast fluctuations in the days ahead.

About the Author:

Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.