Key Points:
- The forecast for Tropical Depression Nine, which is likely to become Tropical Storm Imelda soon, has trended toward a more offshore track, and it now appears that we will escape the threat of extreme rainfall and damaging winds, even along our coast.
- However, there will still be some lesser impacts:
- Heavy rainfall can lead to flash flooding over parts of the Coastal Plain through Tuesday night.
- Beachgoers will have to contend with rough surf and a high rip current risk for the next few days at least.
- The coastal waters will be hazardous through at least Thursday.
- A brisk northeasterly flow will result in minor coastal flooding at high tide, and the pounding surf may result in some beach erosion.
- There exists an alternate scenario where Humberto is unable to pull Tropical Depression Nine / Imelda-to-be out to sea. If that scenario comes to pass, then we risk seeing direct impacts later this week. However, the odds for this are currently very low.
The forecast trend remains favorable for South Carolina. The forecast has shifted to one with Tropical Depression Nine (TD9), Imelda-to-be, staying well offshore and having only limited impacts to the Palmetto State.
The forecast track has trended to one resembling the "escape to the east" scenario from Friday. The storm is likely to stay far enough offshore to keep damaging winds and extreme rainfall over the Atlantic.
The one caveat emptor that we have today is that TD9's slow development opens the possibility that it could not only be left behind by the upper-level trough over the Southeast right now but perhaps also by Hurricane Humberto, which most of our computer models show pulling it away to the east and out to sea. That would allow TD9/Imelda-to-be to wander for a day or two over the southwestern Atlantic and eventually turn back toward the East Coast later this week. However, more than 90 percent of computer model solutions indicate that the storm will turn to the right and follow Humberto away from the East Coast.
The latest storm track density map from polarwx.com shows a strong signal for TD9 to turn to the east; only a few models show a track toward the coast.
So, we'll operate on the assumption that TD9 will strengthen into Tropical Storm Imelda over the Bahamas, then turn to the right once it moves north of the Bahamas and track toward Bermuda. That will keep the worst wind and rain offshore.
However, we'll still see some indirect impacts in South Carolina. The flow between the twin tropical cyclones (TD9/Imelda and intense Hurricane Humberto) and a high-pressure area to our north will throw Atlantic moisture into South Carolina, where it will interact with a dissipating front over us. That will serve to squeeze out soaking rains over parts of our state. Despite the abnormally dry spell we've experienced over the last month or so, isolated flash flooding can still occur, especially along our Coastal Plain. The forecast calls for this area to receive 2-4 inches of rain through Tuesday night, with locally higher amounts potentially reaching up to 6 inches.
Excessive Rainfall Outlooks from the Weather Prediction Center highlight the risk for flash flooding over the next two days (Monday and Monday night at top and Tuesday and Tuesday night at bottom).
While we don't expect to see any damaging wind, gusty easterly to northeasterly winds over the next couple of days will push water into our coast, so that waters will run a foot or two above the usual tide level. We can be thankful that astronomical tides are low because we're near the first-quarter moon phase, but minor coastal flooding is possible at high tide over the next couple of days.
Between TD9/Imelda and the brute Hurricane Humberto (now Category 4, it was Category 5 last night) passing well offshore, our coastal waters are going to be quite angry for a while. The surf along our coast will be rough with a high rip current risk for the next few days at least, and a Small Craft Advisory is in effect for our near-shore coastal waters. A Tropical Storm Warning is in effect beyond 20 nautical miles from shore. Higher water levels and pounding surf will likely result in some beach erosion this week.
Surfer dudes and dudettes, I know y'all can't resist going after the 'cane surf, but promise me y'all will be super careful out there. The surf is going to be angry with two storms out there, causing mixed swells and stout onshore winds, making those waves really choppy.
That should cover it! We can be thankful that the forecast has trended away from the dire outlook it presented to us on Friday. We still need to keep an eye on TD9/Imelda-to-be, but the odds strongly favor its impacts on South Carolina to be limited. That said, we still have a lot of hurricane season to go, so your storm preparations may not go for naught. Of course, any time you need prep advice, you can visit hurricane.sc.
This visible satellite loop zoomed in over the southwestern Atlantic shows Category 4 Hurricane Humberto tracking south of Bermuda and TD9 centered southeast of the Andros archipelago in The Bahamas.
Image Source: University of Wisconsin RealEarth