Over the course of the day today, the messy tropical blob of convection that is expected to become Tropical Storm and perhaps Hurricane Imelda went from being Investigation 94 to a Potential Tropical Cyclone to Tropical Depression 9 earlier today. That indicates the hurricane hunters found an area with a closed low pressure that indicated a tropical depression had organized. The wind speed there was 35 mph, which is below the threshold for a tropical storm, but it is expected to continue to organize and should be named Imelda either tonight or tomorrow morning as the winds around that low increase.
The latest computer models have switched during the course of the day from predicting that Imelda will make landfall on the South Carolina coast to more likely being pulled east due to the circulation around Hurricane Humberto before Imelda’s center hits the coast. Humberto became a category 5 storm today so its pull on Imelda is strong and that is contributing to the change in expected track along with other factors like the cold front moving in from the north. However, not all the models agree and a subset of them still show Imelda making landfall along the coast, so we need to keep an eye on that possibility. If Imelda does take the expected right turn to the east, it will do it slowly so gusty winds, high waves, and heavy rain will hit along the coasts of Georgia and the Carolinas while Imelda is near. Rain could start along the Georgia coast as early as Monday morning, although it now looks like it is more likely to start later in the day. Rain could continue in South and North Carolina for several days if Imelda lingers or moves away very slowly. The exact amount of rain that will fall depends both on the location of Imelda’s center and the speed at which it is moving, since a slower storm means more rain will hit any point than a storm that is zipping along. If the actual path is farther east than what is predicted, then the rain will be more confined to the coast, but if it is farther west than predicted, rain may cover more of Georgia and the other states.
Meanwhile, in Florida, Imelda will be paralleling the coast along the Florida Peninsula. The southern end of Florida could experience tropical storm force winds as early as Sunday evening, but it will most likely be Monday morning before they are likely to experience those. Since Imelda is expected to stay off the Florida coast, the strongest winds and rain are likely to occur over the ocean and not over Florida.
The current cone of where the center of Imelda is likely to travel is shown below as of 11 pm. Keep in mind that the center is only in the cone about 60 percent of the time, so it could still be outside the cone. Also remember that the impacts can spread far outside the cone because of the circulation of air around the center low, so rain and gusty winds can occur well outside the cone. The 11 pm cone has the storm staying farther offshore and turning sooner to the east than earlier forecasts because the depression is moving more slowly and organizing slower than expected, but there is still a spread in the models so things could change on Sunday. Since the latest track is farther to the east, we can also expect the rain accumulations near the coast to be lower than previously expected and only the immediate coastal areas in Georgia will likely get more than 2 inches of rain.
As Imelda continues to develop and organize, the forecast models should start to come into better agreement about where the storm and its impacts are likely to occur, so we will continue to watch and prepare.
