HWRF - 1 AM Friday - Potential Landfall - Cherry Grove Beach, SC. 18Z model from 9/11/18.

Hurricane Florence: Tuesday Night Update and River Gauge Check

Hurricane Florence is creeping ever closer to the Carolinas, yet is seemingly even less predictable. I’m no expert, but quite the weather enthusiast, I’ve been watching weather models that cannot make up their mind. I know that the National Hurricane Center, local NWS offices, local meteorologists, and all kinds of local officials have their hands full trying to predict what this storm is going to do, so remember that when you hear someone criticizing something outside of their control.

Now for the weather update portion. Always start with the National Hurricane Center (https://nhc.noaa.gov). They are the professionals and provide updates quite regularly when a storm is this close. They will issue intermediate advisories at 2AM, 8 AM, 2 PM, and 8 PM, while providing significant forecast track updates at 5 AM, 11 AM, 5 PM, and 11 PM.

The latest is below, as of 8 PM on September 11th:

The NHC is sticking to their guns in the face of model guidance that is creating quite the fork in the road. Disclaimer: Their guidance should be followed as they are professionals and understand the science and the nuances of forecasting without taking numerical weather output at face value. Anyway, almost all guidance is roughly in agreement up until 2 PM Thursday. This can be seen in the image above.

At that point, the European or ECMWF model is showing the storm stalling out for roughly 36 hours short of Cape Fear, NC, and then remarkably heading southwest down the South Carolina coast for a landfall at Hilton Head Island, SC. Below is an animation of this forecast data run, starting at 8 AM EDT this morning. This would normally be a discarded model solution as it is such a massive change, only 72 hours before a theoretical landfall. However, this is usually the best weather model on the planet, so it is not to be taken lightly.

Note: This image is courtesy of Levi Cowan at tropicaltidbits.com. Visit his site for the most in-depth model output for Hurricane Florence. He has collected the largest, most user-friendly collection of map data for hurricane enthusiasts on the Internet.

The other models worth paying attention to due to their skill would be the following:

  • UKMET (United Kingdom)
  • GFS (US – NOAA’s global model)
  • HWRF (One of NOAA’s hurricane-specific models)
  • HMON (A newer one of NOAA’s hurricane-specific models)
  • FV3-GFS (The experimental and future GFS replacement)

The problem is that the UKMET shows a solution that has the storm with landfall at Morehead City, NC, and not stalling out like the others. The most recent GFS, that came out at roughly 6 PM this evening, shows a near-landfall at Cape Fear, NC and stalks down the coast in an extremely similar manner and timeframe as the ECMWF.

The HWRF shows a landfall at Cherry Grove Beach near North Myrtle Beach, SC as a direct hit. The HMON shows a landfall at Topsail Beach near Wilmington, NC. The FV3-GFS shows a solution near the GFS and the European ECMWF model, where the system stalls out and makes landfall further down the SC coast. These models all together paint a picture that there is not an easy solution to forecast. These should all be taken very lightly as there is still quite the run-to-run variance.

I’ve put all of these images in a gallery together below with captions to further explore. Again, all of these images are courtesy of Tropical Tidbits.

Being from Horry County, one thing that I have noticed is that there are too many solutions that would involve vast amounts of rainfall. I will try to get an update out there that covers the potential rainfall solutions being put out by models currently. One safe bet is that this system will do two things: rain substantially in the Pee Dee and also rain in the upriver areas that feed the Waccamaw, Lumber, Little Pee Dee, and Great Pee Dee Rivers. This could cause substantial flooding similar to what was seen during Hurricane Floyd in 1999, which caused rainfall records that still hold to this day. If the storm stalls out as currently prognosticated, this could spell trouble for Northeastern South Carolina.

To monitor this flooding, bookmark this link: https://water.weather.gov/ahps. Once on the website, either select the state of South Carolina or the Wilmington, NC Weather Forecast Office to monitor the Pee Dee in specific.

Currently, I have posted an image below from the National Weather Service’s website monitoring the status of river gauges in the area. Luckily, the rivers are not even at an action stage, so this is at least a thumbs up in regards to having some room to take on some of this projected water. Also, it is neat to see that Nichols has a gauge after theirs malfunctioned during Hurricane Matthew and did not give proper warning to the Lumber River rising. The story of Hurricane Matthew, with many tweets detailing Nichols’ plight, was detailed in a Twitter compilation here.

One last look is at the Waccamaw River at Conway specifically, usually a troublesome area for flooding and one that proved to be during the Great Flood of 2015 and Hurricane Matthew in 2016. The river is in a normal state, but it would not take much inflow to bring the river to a an action level quickly.

Stay tuned for a Wednesday update hopefully with more clarity. I’m not going to even try to guess yet on a storm path or landfall, your guess is as good as mine!

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