Hurricane Florence underwent rapid intensification last night and today and currently has maximum sustained winds of 140 mph. This puts Florence at category 4 strength, and expectations are that further strengthening will occur, given the favorable environmental conditions. It appears that Florence’s strength has currently leveled off for the time being, and with hurricanes of this strength, it is not uncommon for an eyewall replacement cycle to occur. This occurs when an outer eyewall begins to form around the original eyewall. Over time, the new eyewall eventually replaces the old one. Although this can result in temporary weakening, the storm can later strengthen further, and the wind field usually increases in diameter. We will have to see if that occurs overnight tonight or tomorrow.
In this article, I want to focus mostly on impacts, instead of going into a lot of detailed meteorology as I often do in my discussions. Below, I have included several questions that many of you have asked, and I am going to do my best to answer those.
Where is Hurricane Florence going to make landfall?
We’ve managed to get a better handle on where Florence is going, even though there are still some disagreements in the forecast model guidance. That’s normal though! Previously, we outlined a region from the northern Florida coast through the Carolinas. That zone can now be narrowed down a bit further. The region that should watch for a potential landfall extends from Charleston, SC to the northern coast of North Carolina. The latest several runs of the operational European model have consistently projected a landfall around the South Carolina/North Carolina border, and the ensemble means have shown a similar picture, maybe a hair farther south. Even though locations as far south as Charleston is out of the National Hurricane Center’s cone of uncertainty, I want to watch this storm for another 12 hours before taking that location out of the threat zone, especially since Florence has continued to maintain a westward to west northwestward trajectory. As ridging begins to build and strengthen to Florence’s north, we’ll see if it begins on a more northwest trajectory tomorrow.
Hurricane-force winds will extend well-inland from the center of the storm and along areas to the east of the center. Florence is going to slow down significantly as it approaches land; meaning, this may put somewhat of a limit on just how far inland hurricane-force wind gusts will extend. If the storm were booking it, it would cover a lot of real estate before weakening. In this case, hurricane-force winds may ultimately occur over less real estate, compared to a Hugo-type storm, BUT the wind damage that occurs within the first 24-hours of Florence’s landfall could very well reach catastrophic levels. Given that even a small margin of error in track could change the region that will have those kinds of winds, I recommend erring on the side of caution and preparing, especially if you’re on the Carolina coastline and within 100 miles of the coast.
How much flooding will Florence produce, and how widespread will it be?
If Florence makes landfall where it is currently projected, flooding could be widespread and deadly, well away from the storm’s center. Air will be forced upward by the mountainous terrain on the eastern side of Florence, something referred to as orographic lift. This means that rainfall rates could be a bit higher compared to a region that has a hurricane moving over flat terrain. Remember, Harvey was a prolific rain producer because it stalled for days. There will be other factors at play that could enhance Florence’s total rainfall amounts; thus less time will be needed for heavy rainfall totals to occur.
In no way do I want to undermine the wind threat. It’s going to be bad! But, I always take flooding very seriously on Firsthand Weather, especially when I see that it’s going to be a widespread event such as this one. Below, I included an image that shows the Weather Prediction Center’s current projected rainfall totals that will be associated with Florence. As you can see, widespread areas of 10 to 15 inches of rain is expected across North Carolina and Virginia. Many of those locations have already received a lot of rainfall this summer, even recently. I think these totals could be a bit underdone in some places, so assume that there will be regions that could well-exceed above 10 to 15 inch rainfall totals.
Will Storm Surge Be A Big Threat?
The short answer is. . .yes!! For residents along and near the coast, storm surge will be a major issue on the east side of Florence. This is a deadly threat that is often not taken seriously. Even a very small change in track could alter the regions that will get the highest storm surge.
If you are under mandatory evacuations, I strongly urge you to evacuate. There will be some of you who will evacuate and may come to realize by the end of all of this that it wasn’t necessary. However, you don’t want to find yourself in a situation wishing that you had left. You may be putting yourself and your family at risk. It’s generally a good idea to expect the unexpected. When do meteorologists ever get a forecast completely accurate, especially one like this? Never. That’s not a criticism of the science, but instead, it’s something that you should take into consideration. It’s best to plan for unexpected changes in track and intensity that weren’t necessary predicted by professional meteorologists. It’s the nature of the science, and it’s one you should be aware of, especially if you are tempted to believe your area may not be a high-impact area.
If you are unable to evacuate, whether that’s due to financial reasons or whatever else, try to reach out to those who are willing to help. Many of our followers on Firsthand Weather have been providing tips, making others aware of resources that they weren’t aware of, and even offering their homes for free for others to stay. Please go to the Firsthand Weather Facebook page, and we will do our best to guide you to the great amount of information that many of our followers have already provided.