Idalia is just hours away from landfall. The 5am ET forecast overview from the National Hurricane Center is at these links: Key Messages regarding Hurricane Idalia (en Español: Mensajes Claves). This post is an overview of the situation. Given the complexity and nuances of the forecast for coastal Georgia and the Lowcountry of South Carolina, there will be separate post on that coming up.
Idalia continued rapid intensification overnight and NHC now has it as a 115 knot (130mph) Category 4 storm. Here is what it looks like on radar just before 5am:
Here is the forecast impact swath, using my TAOS/TC model and based on the National Hurricane Center forecast. The biggest change overnight is that NHC has bumped up their inland wind forecast. This is a pretty grim for the Big Bend area of Florida near landfall:
You can expect catastrophic damage near the landfall location. While sparsely populated by Florida standards, it is a very vulnerable (and beautiful) area. A lot of the impact area is covered by the Big Bend Wildlife Management Area and other preserves, which is good. But on the coast where we can expect 15ft storm surges, Stinhatchee, FIsh Creek, Horseshoe Beach, down to Cedar Key are going to get hit hard. Tallahassee is on the left (west) hand edge of the “bad” damage swath, and Lake City on the right (east), with Perry and Live Oak also going to get hit by high winds. Inland both in Florida and South Georgia (Valdosta-Waycross corridor) there is a lot of vulnerable manufactured housing. On this track and intensity, economic impacts are expected to be on the order of $5 to $8 Billion, $10 Billion is not unreasonable depending on how organized and strong the storm stays inland.
For the Georgia/SC coast the situation is complex. The short version is that winds might be higher than forecast yesterday with all that goes with it, limbs down, power outages, maybe a tree or two, along with heavy rain … but it’s complicated, thus the need for a longer specific post. We’re still in the “scary, inconvenient, hazardous if you go out in it, but not dangerous for the vast majority of people who stay home and ride it out.” The one issue everyone is concerned about is coastal flooding, with memories of Irma and Matthew still fresh. It doesn’t look like that kind of storm – the tides at 9pm will be well above normal and in to flood stage, pushing 10.5 or maybe even 11 feet, and the usual areas that flood on spring tides near the equinoxes will certainly get water. However, that is several feet below the levels seen in those previous disasters. Again, more details coming up in a bit …