We remain on track to see beach and boating impacts from Hurricane Franklin over the next few days and direct effects from Tropical Storm Idalia at midweek. We'll start by looking at the current satellite showing where the storms were this afternoon.
A loop of true color satellite images shows our terrible twins of Franklin over the western Atlantic and Idalia over the northwestern Caribbean Sea. Their forecast track and uncertainty cone is overlaid on the imagery.
And here's a more detailed view of Idalia's forecast track from the National Hurricane Center (NHC).
The forecast track from NHC for Idalia from Advisory 5, issued at 5 p.m. EDT.
Confidence has increased in the forecast for Idalia's track since yesterday. The Hurricane Hunters have been flying through Idalia to assess its structure and flying around the storm to take measurements of the atmosphere surrounding the storm. All this data gets fed into computer models, which improves their output.
The track has been shifted a bit to the right since yesterday, which is good for some parts of the Palmetto State. The computer models have come into better agreement on the track since yesterday, so we have more confidence in the forecast about where it will go.
What's less certain is how strong Idalia will get while tracking over those 86-90°F waters of the eastern Gulf of Mexico. It's very concerning that our hurricane-specific models show a period of rapid intensification while Idalia moves through this area and make it a major hurricane before landfall in Florida. It's because of this guidance that the NHC forecasters have increased the intensity forecast and call for it to be packing 100 mph winds just before landfall in Florida early Wednesday morning and 60 mph winds Wednesday afternoon as it's moving into South Carolina. The concern is that the storm could be even stronger at landfall in Florida, and then stronger for us downstream in South Carolina. The farther east track also puts more of the storm over water while it's affecting us, which allows for the storm to maintain more of its intensity while on the way through.
So, wind impacts are increasingly looking significant for us; the current forecast is for a strong tropical storm scraping our coast Wednesday afternoon and night with 60 mph sustained winds and potential gusts to around 70 mph, strong enough for tree and power line damage. Stronger winds are possible; a Category 1 hurricane is likely our worst-case scenario should Idalia get much more intense than forecast before reaching Florida.
Storm surge would be in the 2-4 foot range if the forecast is correct. The main concern is that the storm will hit during a full moon and high astronomical tides. A surge of this magnitude will be tolerable if it comes at low tide, but we'll see major flooding if the worst surge comes at high tide when the high tide alone could cause flooding. Add to this the potential for tropical downpours at the same time. Our coast is at risk of seeing some very significant flooding Wednesday afternoon and night if the timing of surge and high tide is just right. It's too early to say it will be, but I recommend being ready for it.
Rainfall will be a major factor with this storm, too. The eastward shift in the forecast track should spare the Upstate the worst of Idalia's rain, but as outlined yesterday, a front moving in and becoming stationary for the next few days will bring locally heavy rainfall to that part of the state and risk for flash flooding. Over the rest of the state, rainfall from the front will be less substantial on Monday and Tuesday, but Idalia's rain comes on Wednesday and Wednesday night with flash flooding possible. The big question now is the extent of overlap between the front's heavy rainfall and that from Idalia. The best chance for this overlap will be in the I-20 Corridor and especially in the Pee Dee. There is enough track uncertainty still that this area may be moved or expanded as we get closer to the event. The dry conditions of recent weeks in the Midlands, Catawba area, and Pee Dee region help us here, reducing the risk of river flooding. However, minor river flooding is a possibility.
WPC's Excessive Rainfall Outlooks for Monday
WPC's Excessive Rainfall Outlooks for Tuesday
WPC's Excessive Rainfall Outlooks for Wednesday.
As is usually the case with landfalling tropical cyclones, there will be a tornado threat along our coast as Idalia moves through Wednesday and Wednesday night. The eastward shift in the track since yesterday reduces the area at risk.
Hopefully, the eastward trend in the forecast track continues as we get closer to the event and details on Idalia's forecast get clearer. The more to the right of the current forecast track, the better, but don't count on it. Count instead on your storm preparations, which need to be underway. If you have questions about what you need to do to get ready, the place to go is hurricane.sc.
I'll see y'all again tomorrow.