Potential Tropical Cyclone 8 dumping exceptional rainfall near Wilmington, NC

Headlines

  • Major flooding just south of Wilmington, NC has been occurring due to Potential Tropical Cyclone 8.
  • Additional rain and flooding, in addition to significant marine impacts and coastal impacts on the North Carolina coast are expected in the region through tonight as PTC 8 moves inland.
  • Gordon is a depression, but no other systems are noted in the Atlantic or off Africa right now.
  • We continue to see signs that the Caribbean will be the next place to watch next week, with potential development continuing to show up as noise in the forecast.

PTC 8 causing a ruckus in North Carolina

The good news is that Potential Tropical Cyclone 8 is running out of time to potentially become a tropical cyclone. The bad news is that it has been causing a lot of mischief in North Carolina since yesterday.

PTC 8 is running out of real estate before it comes ashore. (NOAA NHC)

Rain totals have been absurd in some parts of North Carolina, almost doubling forecast expectations for the week. The Wilmington, NC area has been especially hard hit with a bullseye of radar estimated rainfall near 20 inches just south of the city. The highest official total I can find is 15.25″ at Sunny Point, which aligns well with the scale below. There has been severe flooding in portions of Brunswick and New Hanover Counties, in North Carolina.

Ridiculous amounts of rain have fallen in southeastern North Carolina, focusing on the areas near Southport, Carolina Beach, and Wilmington. (NOAA MRMS)

Recurrence intervals appear to be over 200 to 250 years with this rainfall, making this an exceptional, historic event for this area.

Rain continues, though there may finally be some feeder band movement offshore that indicates a focus may shift out of Brunswick and New Hanover Counties and off to the northeast a bit. Those areas have seen comparably less rainfall.

Rainfall continues in southeastern North Carolina as PTC 8 approaches. Rains should settle down some after this afternoon though and the focus shifts inland. (Weathernerds.org)

Winds have been ripping as well, with gusts as high as 67 mph in Wrightsville Beach, 64 mph just south of there on Masonboro Island, and 60 mph in Wilmington. A 77 mph gust at Sunny Point south of Wilmington was taken a bit elevated, at 30 feet, so it may not be especially representative. But anyway, this is why we noted yesterday that whether it is or isn’t a tropical storm (it still isn’t technically) the impacts would be the same.

Not to be outdone, but winds and waves have been solid and high farther up the North Carolina coast with some damage to homes being reported as far north as Rodanthe on the Outer Banks. Beach erosion and ocean overwash is likely to continue into tonight across the North Carolina coast as PTC 8 moves inland. Coastal flooding of 1 to 3 feet is likely as well, with waves of 8 to 12 feet near the coast and to the north of Wrightsville Beach or so. Things will settle tomorrow.

In addition to all this mess, isolated tornadoes are a good bet in parts of eastern North Carolina.

Flood risk will move inland tonight, with totals of anywhere from 3 to 7 inches between the western North Carolina mountains, Charlotte, and into southeast North Carolina away from the coastal deluge. Higher amounts are likely in a few spots, especially near or south and east of Raleigh.

Rain totals of 3 to 7 inches are expected over a wide area of interior and southeast North Carolina. Higher amounts are likely. (NWS Raleigh)

Rains will become more scattered after today and tonight, and conditions will generally improve in North Carolina and the Mid-Atlantic after that.

Gordon downgraded, and no other Atlantic Ocean items to watch

Tropical Storm Gordon was downgraded to a depression, and it will continue to meander in the open ocean for a few days. There is a decent chance that Gordon will make another go at intensification later this week or weekend. Its future keeps it in the open ocean, the first true fish storm of 2024.

Gordon continues over the open ocean, no threat to land. (NOAA NHC)

Elsewhere in the Atlantic, conditions look quiet over the course of this week, and we do not expect any new systems of note to form. So we can spend most of the rest of the week waxing poetic on…

…The Caribbean

Yes, we continue to see signs that the Caribbean will be an area to watch in a week or so. We’ve started to see operational model runs begin to ramp up activity out of that area, though I strongly advise folks to disregard those one-offs, especially with regard to specifics. What do we know right now?

First off, we know that the overall atmosphere in the western Atlantic and Caribbean is going to become more hospitable to tropical development. After a period of hostile conditions that has basically been continuous since early August, the western Atlantic is going to flip to a more favorable background state for tropical development. In other words, less sinking air and more rising air will at least promote more development opportunities.

After weeks of sinking air in the background of the Atlantic, we see signs of a major flip after this week that could promote a busier period of tropical activity. (StormVista)

So the background state says that we should get moving. Second, we have seen signs in modeling of some type of either gyre scenario over Central America or the western Caribbean or some sort of disturbance that arrives there around early next week. This has been a feature in ensemble modeling for a while now, and it’s beginning to materialize in other modeling too as we get closer. But if you look at the GFS ensemble of sea-level pressures this coming Sunday, you can see a decent signal for low pressure in the northwest Caribbean.

A decent signal for low pressure in the northwest Caribbean next week may indicate that our next system is on the horizon. (Tropical Tidbits)

This isn’t a flashing red lights signal but it’s enough for me right now. I’ll be watching this area closely. Exactly what happens from here remains to be seen, but we know that the environment will become increasingly hospitable, and this is some of the warmest water in the basin. It absolutely merits paying attention in the days ahead, whether or not anything ultimately occurs.

A Mid-Atlantic soaker as a coastal storm lurks off the East Coast

Headlines

  • Low pressure off the coast of the Carolinas will focus heavy rainfall this week, particularly in eastern North Carolina, along with some coastal flooding and rough seas.
  • Tropical Storm Gordon remains well out at sea, of no concern to anyone.
  • We continue to see hints that a system may make an effort to develop in the Caribbean after this week, but details remain elusive.

Carolina soaker

Low pressure and an associated trough off the coast of the Carolinas today is flinging rain back into southeastern North Carolina and the Myrtle Beach areas in South Carolina.

Low pressure sits offshore of South Carolina, and as it drifts northwestward, it will bring a dose of heavy rainfall to North Carolina in particular. (NOAA WPC)

This area of low pressure has an outside chance to form into a tropical entity before coming ashore in North or South Carolina tonight or tomorrow. Whether it does or does not, the impacts should be fairly well baked in right now, which is to say heavy rain, rough seas, some minor coastal flooding and erosion, and breezy conditions are likely in the Carolinas. Depending on the exact track of the storm, we’ll see where the heaviest rainfall sets up.

Rain totals of 3 to 7 inches are likely in eastern North Carolina and southeast Virginia, as well as in parts of the Blue Ridge this week. (Pivotal Weather)

Total rainfall should be highest in eastern North Carolina, where 3 to 7 inches is possible. There will also probably be a localized maximum of rainfall in the northern Blue Ridge in Virginia as well. A large area of moderate rain this week will surround all this from South Jersey into the Triad in North Carolina.

This system will linger onshore for a few days, so it only has about 18 to 24 hours left to formally develop if it does at all.

Deep tropics

Tropical Storm Gordon is likely to get downgraded to a depression soon. It may linger in the open Atlantic for a few days before it perhaps finds a more hospitable environment to reorganize later this week.

It’s the Gord*D*on’s fisherman. (NOAA NHC)

Either way, it will remain out at sea, no threat to land.

Behind Gordon, we have no concerns over the next week or so in the eastern Atlantic.

Caribbean watch

This week will be quiet in the Caribbean as well. However, there continue to be signs and signals that something may get going there after this week. It’s all conjecture at this point, but there’s enough there there to keep us at least paying attention in that region after this week. Not much else to say on this right now. More to come on this through the week though I am sure.

Gordon forms way out at sea but the only short-term item to watch is off the Carolinas

Headlines

  • Tropical Storm Gordon is of no threat to land.
  • A low pressure system in the Southeast is a tricky forecast but likely to cause heavy rain and flooding concerns next week in the Carolinas or Virginia, as well as marine impacts.
  • Longer-range modeling suggests that we’ll be watching the Caribbean and Atlantic closer in about 2 weeks.
  • Thank you to our Friday featured sponsor: The Heitmann Insurance Agency!

Of note for our Houston readers (or other interested parties), over at Space City Weather, Eric posted about the “western shift” in Francine’s forecast on Monday that, if anyone follows me on social media knows exasperated me. The reality is that hurricane forecasts are subject to change, and although the Beryl forecast was mediocre at best, especially a few days ahead of the storm, every storm is unique. No two storms follow the same exact rules, and if we see a reason to expand a region of concern, we will. I saw social media posts emphasizing a dramatic western shift, a specific concern of a threat of “more impacts to Houston,” among other poor takes across social media from weather enthusiasts and (importantly!) meteorologists alike. It’s exhausting, but we will continue to operate this site as we have since inception and as we operate Space City Weather, which is to say with honesty, transparency about the data and our thinking, and accountability when we get it wrong.

Tropical Storm Gordon & friends

Storm number seven of the Atlantic hurricane season has formed, with Tropical Storm Gordon out in the open Atlantic. It is of no threat to land.

Tropical Storm Gordon will swim with the fishes. (NOAA NHC)

Gordon looks decent on satellite imagery this morning, but it is so far north that it will eventually run into dry air and likely suffer the consequences. Of note, it appears the Gordon will be the first storm of the Atlantic hurricane season to miss land.

Meanwhile, the two invest areas approaching the Caribbean have become one invest area. Invest 92L is gone, but Invest 94L has maybe a very, very slight chance to briefly form this weekend before it likely has to deal with too much land.

Southeast low pressure to cause headaches

The Southeast coast will be an area to continue to watch heading into next week. Tomorrow and Sunday will see a cold front slide off the Southeast coast with an area of low pressure spinning up along its remnants.

Surface map forecast for Saturday in the Southeast. (NOAA WPC)

This won’t be a “true” tropical system, but it may eventually try to develop into a subtropical-type storm or depression off the coast. In general, it would track generally slowly northward or northwestward. Although this probably won’t be a true tropical system, it will probably behave like a tropical storm or decent nor’easter off the Carolina coast. This means heavy rain and coastal impacts will be possible. So don’t focus on classification nuance here. Current rainfall forecasts show upwards of 4 to 8 inches over the next week on the coast of North Carolina.

Heavy rain is likely over the next week or so in the Carolinas and possibly Virginia due to low pressure off the coast. (Pivotal Weather)

Depending on exactly how this unfolds and tracks, there could be a pretty significant flooding threat in the Carolinas next week, in addition to rough seas, beach erosion, and tidal flooding risk. Rip currents will also be strong this weekend. Stay tuned for more on this. We’ll have an update on Sunday for you.

Notably, after praising the ECMWF AI (AIFS) model and ICON yesterday, those models are struggling with this area as well, so this is a low confidence situation.

Late September: It may get busier

Looking down the road, there is reason to believe that the Atlantic may be shaping up to get a bit busier. We can have some pretty wild Octobers. Just look to 2020 for evidence of that. After weeks of a background of sinking air over the Atlantic basin, the background is likely to shift to more rising air. This supports and sustains tropical development. It may help reduce some of the drier air that has plagued the basin as well. In general, it just looks healthier for more activity after next week.

One area that models are honing in on is the western Caribbean. We’re seeing signals on the ensembles and the European AIFS model for some sort of spin up possibly occurring there in about 12 to 14 days. It has been showing up for a couple days now, and this overall shift to a more hospitable pattern supports it happening. The ECMWF sub-seasonal/weeklies model from yesterday shows above normal tropical activity in week 3 today.

Above normal activity is forecast in the Atlantic in late September and early October. (ECMWF)

This is the first time I’ve seen this in a while, which seems to indicate that this idea of a possible Caribbean system or more Atlantic activity in general is actually supported in the models too, not just theoretically. So, it’s still a couple weeks out, but this gives you an idea of where we’ll be looking as we head toward later September.

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Francine exits as attention shifts to a bunch of middling Atlantic action

Headlines

  • Francine will likely produce flash flooding, particularly in Alabama and Tennessee over the next couple days.
  • We recap Francine below with info on how AI modeling did and why New Orleans saw worse conditions than expected earlier in the day.
  • The Atlantic looks more active than it actually is, with two invests that should not develop and one depression that may become a named storm and stay out at sea.
  • A subtropical or tropical system may form off the Southeast coast next week.

Thanks to folks in Louisiana that followed along with us through Francine, and we hope you’ll spread the word and stick with us. We did experiment with a new format yesterday by updating the AM post instead of pushing new posts all day. Any feedback is appreciated.

Francine recap

With Francine down to depression status and dissipating, I want to just point out a couple odds and ends related to the storm.

Current forecast

The rainfall forecast for the rest of the week is pretty stout in the Southeast, with as much as 6 to 8 inches of rain possible across portions of Alabama and Tennessee.

Rainfall over the next 3 days from Francine’s remnants could drop as much as 6 to 8 inches or more across Alabama and portions of Tennessee, leading to flash flooding. (NOAA WPC)

Flash flooding and localized severe weather will be the primary impacts of Francine’s remnants over the interior. A good idea to remain weather aware, particularly between Birmingham and Huntsville due to flooding.

AI modeling & ICON scores a big win

I went through and assessed the 15 model runs leading up to landfall from various models with Francine. Keep in mind that the landfall point is not the only variable that matters, but it’s an important one. And one thing you cannot tolerate as a forecaster is a lot of whipping around within the models. Enter the European AI model, the AIFS. Here are the 15 runs leading up to landfall with Francine:

AIFS model 15 runs leading up to landfall with Francine. (Tropical Tidbits)

This is a remarkable feat of stability. The AIFS showed landfall between Vermilion Bay and Grand Isle run after run after run. Ultimately, it came in on the eastern half of that spread, but the consistency was some of the best I have ever seen with respect to a tropical system. The timing and intensity bounced around a bit, but not so much as to make the tool useless. It had immense value, and it’s one of the reasons we were very bullish about this not being a serious Texas concern. This was a lesson learned from Beryl. And not to be outdone, the ICON also showed a healthy amount of stability run to run in terms of track.

ICON model for 15 runs leading up to landfall with Francine. (Tropical Tidbits)

While the ICON kept western Louisiana in play for a while, it too corrected east in time. This, combined with its performance during Beryl (as well as last week with Invest 90L) made it another valuable tool. Will these models fail in the future? Yes, all models do. And the ICON remains prone to spurious tropical systems that never end up happening. But at this point, I think there’s a lesson to be taken from this as a meteorologist. particularly when the models show this sort of stability. The GFS and Euro operational model (and the ensemble guidance) also performed respectably, but those models showed less consistency run to run than did the ICON and AIFS.

Last minute lurch to New Orleans

In yesterday’s morning post, we noted the forecast for New Orleans showed maximum wind gusts forecast to be 57 mph. They gusted to 78 mph. The reason was twofold. First, the storm had a quick late burst of intensification (in the face of wind shear no less) on approach to landfall. This led to an eastward shift at the last minute. Instead of coming in right at Atchafalaya Bay, it came in a more of a slanted angle just east of there. This, coupled with the stronger intensity pushed the eyewall into the New Orleans metro area leading to wind gusts of 60 to 80 mph. Hurricane forecasting remains imperfect.

Of note, thus far the highest wind gust I have seen is 96 mph in Dulac, LA. There were two 100 mph gusts south of Burns Point, LA, but those I believe were on elevated oil platforms which would have higher winds than at surface level. The highest rain total was in Mandeville, at just over 9 inches. New Orleans saw over 8 inches in the city. Officially, they reported 7.33 inches at the airport, the 9th wettest day on record there.

Atlantic action amplifies

Turning our attention back to current matters, let’s take a look at the Atlantic this afternoon.

It’s less busy than it looks, really. (NOAA NHC)

There are two invest, a tropical depression, and an area to watch in the Atlantic today. We’ll cover the area to watch below. But in the meantime, Invests 92L and 94L just east of the Caribbean are not really of any concern. Those should dissipate before acquiring the ability to develop. So nothing to see here right now.

Meanwhile, Tropical Depression 7 will probably make an attempt to become Tropical Storm Gordon, which somehow hasn’t been retired, despite being used since 1994 in perhaps its most memorable iteration. But Gordo will probably remain out at sea.

TD 7/future Gordon’s track. (NOAA NHC)

Otherwise, the Atlantic is quiet for now.

Southeast system next week?

Things may get interesting next week, to an extent, off the Southeast coast as a remnant cold front could help spawn a disturbance off the Florida, Georgia, or South Carolina coast.

This morning’s GFS model shows a disturbance off the Carolina coast as early as Friday night. (Tropical Tidbits)

Exactly how this evolves is a bit tricky since remnant fronts tend to be a little difficult to exactly predict. But in general, watch for a disturbance to form off the Southeast coast. Because it’s forming from a front, it would probably be non-tropical or “subtropical” in nature. It may have some time to develop into a tropical system over the Southeast coast’s warm waters early next week before likely coming ashore somewhere in the Carolinas. Intensity-wise, it’s a bit early to get too cutesy, but this would probably be slow to organize and develop, so it would probably be a tropical storm at most. But regardless, watch for heavy rain risk next week in the Southeast due to this system. More to come.

We will leave it there for now, but tomorrow we’ll talk a bit more about the longer-range and why things may start getting busy again by the end of September.