The southeastern coast of the United States faces a potential threat from what is likely to become a tropical storm and ultimately Hurricane Imelda. Interests from coastal Florida to Virginia should be on alert and start thinking about plans, particularly in the Carolinas. Here are four looming concerns as we approach the weekend.
Uncertainty In Timing And Formation
The storm has not fully developed. Right now, Hurricane Humbert is the main feature in the Atlantic Ocean. It is expected to strengthen to a major hurricane this weekend and ultimately move out to sea. Humberto is not the storm that will directly affect the United States, but its presence could influence the next storm expected to form.
A disturbance over the island of Hispaniola is likely to become a tropical storm and possibly a hurricane over the weekend. If it does, it will be called Imelda. What worries me about this storm is that it has not fully formed yet, though the National Hurricane Center gives it a 90% chance to do so in the coming days. Once it forms, the forecast models will gain a better handle on the storm structure and motion. Additionally, we know from previous experience that the public often struggles to react to a storm until it has a name.
The National Hurricane Center wrote, ” Showers and thunderstorms continue to show signs of organization in association with a tropical wave located near Hispaniola, the
Turks and Caicos Islands, and eastern Cuba. An area of low pressure is expected to form along the wave by tonight when it moves near the southeast Bahamas.” They went on to say the low would likely become a tropical depression near the Bahamas. NHC ended its Friday morning outlook with a cautionary note. They said, “While there remains considerable uncertainty in the long-range track and intensity of the system, there is a significant risk of wind, rainfall, and storm surge impacts for a portion of the southeast U.S. coast early next week.”
Where Will It Go?
At this point, I will caution you against sharing, without context, single-run outcomes of the “scariest” outcome. There are a lot of social media sites and individuals that cherry-pick outcomes and post them without context. They get shares and likes but create misinformation too. It is important to convey, however, that several of our best models continue to project landfall in the Carolinas. Emerging model consensus is always something that provides our meteorological community with confidence.
The National Hurricane Center has not issued an official forecast cone yet, but that will likely happen within the next few days once the storm forms. Responsible meteorologists rely on ensemble information from the models rather than a single outcome. Ensemble information shows a cluster around the Carolina coasts, but it also indicates that a few members turn the storm out to sea. For now, most forecasters are leaning on the consensus, however, interactions with Humberto and other factors add to the uncertainty.
The Carolina coast looks to be the likely outcome, but I would be irresponsible to not acknowledge considerable uncertainty. Since I have provided necessary context, I offer two single outcomes from the American and European models, respectively. In the graphic below, both models place the storm near the Carolinas by Monday afternoon, but there are some differences. The American model produces a stronger and earlier-arriving storm than the European model. My advice is to take these model runs as guidance not gospel right now and monitor how they evolve in the coming day or so.
The Florida And Georgia Coast
While much of the focus has been on Carolinas, the storm could get close enough to the Florida and Georgia coasts, respectively, to have impacts. Such impacts could take the form of windy conditions, rain squalls, rip currents, and swells, so people in those regions should be on alert. The Bahamas will certainly feel more direct impacts as the future storm develops and moves northward.
A Slight Stall?
One final thing that caught my eye in the European model run is worth a mention, but it may ultimately be a single-run artifact. The European model run stalls the storm near the Carolina coast for several days. When I see a stalled storm, especially near warm Gulf Stream waters, it always gets my attention. Stalled storms can produce sustained rainfall, wind, and surge impacts. The American GFS model does not currently show the storm stalling. This subtle difference in model outcomes is why I urge you not to anchor to one specific outcome right now. Instead, monitor information from the National Hurricane Center as they will have the right expertise to interpret nuances of future model runs, potential Fujiwhara interactions, and so forth.
Meteorologists like me are always weary of storms that start with “I” so keep a close eye on this situation.
