September 23, 2023 Outlook: Ophelia inland and newly formed TD 17 expected to miss the islands

One-sentence summary

Tropical Storm Ophelia is inland and weakening, providing heavy rain from North Carolina into Virginia today, with local moderate to major tidal flooding possible again this evening in the Mid-Atlantic.

Tropical Storm Ophelia: 50 mph maximum winds, moving N 13 mph

Ophelia is now inland and weakening over North Carolina after making landfall earlier this morning near Emerald Isle, NC as a 70 mph tropical storm. The center is just north of Greenville as of this writing, moving due north at a steady clip. Heavy rain is falling across much of interior eastern North Carolina, as well as most of southeastern Virginia.

Ophelia is moving north in North Carolina, bringing heavy rain and flash flooding to parts of the area. (RadarScope)

There is a moderate risk of flash flooding (level 3 of 4) today for southern Virginia and northern North Carolina. Another 1 to 3 inches of rain is easily likely in spots. Those that see the heaviest rain will be most prone to localized flash flooding. Expect inconvenient travel across much of the region today.

A moderate risk (3/4) for flash flooding is posted for the Richmond area into northern North Carolina. (Pivotal Weather)

Tidal flooding remains a concern. The high tide cycle later this afternoon and evening will probably be the last serious one, but we still expect moderate to locally major tidal flooding between Hampton Roads and the Jersey Shore.

Widespread moderate and locally major tidal flooding will be a concern with the late afternoon or evening high tide cycles in the Chesapeake and Mid-Atlantic. (NOAA)

Heed the advice of local officials to ensure you’re prepared for any flooding of streets or vehicles that may occur on the coast.

Additionally, winds continue to blow with Ophelia moving inland. Though, truthfully, the most recent map of wind gusts 35 mph and higher is not exactly going to scare anyone.

A modest amount of 35 to 50 mph wind gusts (there’s a 49 not shown here on the coast of Delaware at an elevated site) are occurring, but nothing that should cause severe issues. (NOAA)

There are a modest amount of power outages, which right now sit at around 60,000 or so. All in all, not terrible. So the main concerns today will be around the rainfall flooding and the high tide cycle later today. Use caution and don’t drive into flooded roadways.

We’ll get more rain into tomorrow as you work up the coast, with 1 to 3 inches possible and a slight risk (level 2 of 4) of flash flooding from the Philly area up into southwest Connecticut, including much of New Jersey and New York City.

Otherwise, we’ll lose Ophelia tomorrow or Monday, and it will dissipate offshore. Some models do show its remnant “energy” hanging around offshore, but right now that seems like a non-serious concern. We’ll keep tabs on it regardless.

Tropical Depression 17: Deep Atlantic system unlikely to impact land

Within the last hour or so, the National Hurricane Center upgraded Invest 90L to Tropical Depression 17. This is the deep Atlantic system we’ve been watching for awhile now in modeling. The good news is that most trends have adjusted to turn this thing north before it gets near the islands. A “close miss” is not off the table, but this is looking more and more like a clear miss.

Tropical Depression 17 is expected to become Tropical Storm Philippe this weekend before turning northwest or north before arriving in the Caribbean islands. (NOAA NHC)

The system is expected to gradually strengthen over the next few days, becoming a tropical storm (named Philippe) later today or tomorrow and eventually a strong tropical storm. It could eventually become a hurricane, but that’s not currently forecast officially. Whatever the case, at present this is no threat to land.

Beyond these two systems, there is not anything of serious concern at this point in the basin. Hopefully we are now past the peak of hurricane season and we’ll see if the secondary, lower October peak brings us anything of note.

Ophelia threatening to become a brief hurricane as it approaches the coast of North Carolina overnight

One-sentence summary

Tropical Storm Ophelia may try to become a category one hurricane before making landfall overnight along the coast of North Carolina, causing wind, storm surge flooding, heavy rainfall and flash flooding, tidal flooding, beach erosion, and rough surf from North Carolina through New Jersey.

Tropical Storm Ophelia: 70 mph maximum winds, moving NNW at 12 mph

What’s changed since this morning?

A lot. PTC 16 produced enough evidence to be classified as a tropical storm and acquired the name Ophelia. Additional strengthening, a bit beyond what was expected occurred, and Ophelia is on the fringe of category 1 hurricane intensity. Thus, we now have Hurricane Watches hoisted between Surf City, NC and Ocracoke Inlet.

Tropical Storm Ophelia sits about 80 miles off the coast of North Carolina as a strong tropical storm. It will make landfall overnight and quickly weaken. (RadarScope)

Rain totals are likely a little higher looking as well, with an additional 2 to 5 inches possible on top of the 1 to 3 inches that has already accumulated in parts of North Carolina.

The Pamlico Sound area and southeast North Carolina is highlighted for an increasing risk of flash flooding over the next several hours by the National Weather Service. (NOAA)

As much as 6 to 8 inches total may fall over parts of southeast North Carolina, which would yield areas of flash flooding.

Surge of 2 to 6 feet is likely from south of Pamlico Sound up into the lower Chesapeake, including the Virginia Tidewater. (NOAA NHC)

Tidal impacts

Peak storm surge values as high as 6 feet are now forecast for the mainland side of the Pamlico Sound in North Carolina. Some moderate surge values may occur near the mouths of the Pamlico, Pungo, Neuse (including New Bern), and Bay Rivers. Moderate to locally major tidal flooding is forecast in the lower Chesapeake Bay (as well as a couple sites in the upper bay), the Tidewater, Delmarva Peninsula, Delaware Bay, and Jersey Shore.

Several tidal gauges are forecast to achieve moderate to major tidal flooding from Ophelia. The hardest hit areas should be around the Lower Chesapeake Bay and Hampton Roads. (NOAA)

This will primarily cause inconvenience, but there will likely also be some reports of damage due to inundation and/or beach erosion and wave action along the beachfront of the Atlantic. Even with Ophelia making landfall and weakening tomorrow, the worst high tide cycles in the Mid-Atlantic will probably occur Saturday evening.

Obviously, the surge could be locally damaging near where Ophelia comes in for portions of North Carolina and western shore of Pamlico Sound.

Otherwise, wind will be noticeable up and down the coast, worst near the center in North Carolina. And heavy rain will be a concern, especially in North Carolina. Stay safe and follow the advice of local officials. More in the morning.

September 22, 2023 Outlook: East Coast expecting legitimate impacts from PTC 16, while Atlantic wave may turn out to sea

One-sentence summary

Potential Tropical Cyclone 16 (which will likely take the name Ophelia later today) will deliver tropical storm impacts to a broad swath of the Mid-Atlantic coast between the Jersey Shore and North Carolina, with heavy rain, gusty wind, surge and tidal flooding all likely regardless of naming or classification.

Potential Tropical Cyclone 16 (likely to become Ophelia)

Here are the key points on what we’ll refer to as PTC 16:

  • Tidal flooding will be a serious issue for portions of the Lower Chesapeake and Delaware Bays, as well as along the coast between the Outer Banks and Jersey Shore. Locally major tidal flooding is expected from Delaware south to the Virginia Tidewater.
  • Tropical Storm Warnings are posted between Cape Dear, NC and Fenwick Island, DE, including Albermarle & Pamlico Sounds and much of the Chespeake Bay roughly south of Easton, MD. Storm Surge Warnings are posted from Duck, NC through Chincoteague, VA, the Lower Chesapeake Bay, the Neuse & Pamlico Rivers in North Carolina, as well as portions of the sounds. Storm Surge Watches cover additional ground beyond there.
  • PTC 16 will have a broad wind field, meaning a wide swath of 30 to 50 mph winds should be expected from the Carolinas through Long Island. The strongest wind will likely be confined to a small area near the center, which should come ashore between Cape Hatteras and Cape Fear in North Carolina.
  • Widespread moderate to heavy rain is expected between North Carolina and Southern New England with flash flooding potential highest in coastal North Carolina near the center of PTC 16.
PTC 16 will track north or northwest toward the coast of North Carolina through the weekend and should dissipate over Delmarva or New Jersey by Sunday and Monday. (Tomer Burg)

Potential Tropical Cyclone 16 is gradually organizing this morning off the coast. Despite having maximum sustained winds of 50 mph, it is still considered a “potential tropical cyclone” because it has not yet shed the technicalities (ie: fronts) that make it a non-tropical entity. For all intents and purposes this is already a equivalent to a tropical storm and should be prepared for as such. The NHC says that this will likely take on a subtropical or tropical tag once the frontal boundaries are shed, meaning it would become Ophelia.

Though technically not yet a defined tropical entity, PTC 16 checks all the other boxes. This is essentially already a moderate tropical storm sitting off the Carolina coast. (

Let’s walk through the expected impacts from PTC 16.

Coastal impacts

In my view, this is the most important aspect of this storm, and it’s the one that may cause the most problems. Current tidal forecasts show a significant number of stations in the Mid-Atlantic expecting moderate or major tidal flooding from the storm this weekend.

Numerous tidal gauges on the coast between Virginia and New Jersey are expected to reach moderate to major tidal flooding this weekend as PTC 16 approaches. (NOAA)

Let’s pick out a couple gauges to talk about real quick.

We’ll start in Norfolk, VA which is expected to see moderate tidal flooding, with a couple gauges nearby pinging major flooding in their forecasts.

Moderate to major tidal flooding is expected in Norfolk, with the gauge at Sewell’s Point expected to peak around 6.4 feet on Saturday early morning. (NOAA)

For the James River at Sewell’s Point, the 6.4 feet forecast tomorrow morning would be the highest tidal reading in Norfolk since Hurricane Joaquin in 2015. Historically, tides at these levels are likely to inundate portions of the waterfront in Norfolk.

For Lewes, DE on the Delaware Bay, this storm will likely produce the highest tides since January 2016 (the blizzard that was dubbed by The Weather Channel as “Jonas.”). Although Lewes will fall a solid foot or more shy of the record, this will still be borderline major flooding for the Delaware Beaches.

Lewes, DE will likely see borderline major tidal flooding from PTC 16. (NOAA)

Flood levels of this nature will tend to cause mostly roadway flooding for Sussex County, DE but some structural damage is possible, particularly if tides come in higher than forecast.

Storm surge flooding is likely into North Carolina as well, in the Storm Surge Warning area.

Storm surge as high as 5 feet is possible along the Pamlico River and mainland side of Pamlico Sound in NOrth Carolina. Surge of up to 2 to 4 feet is generally expected between Surf City, NC and Chincoteague. (NOAA NHC)

In addition, we are expecting waves of 10 to 15 feet just offshore. The combination of high tides and rough surf will likely lead to beach erosion issues up and down the East Coast. I imagine some beachfronts are a bit more vulnerable after dealing with rough surf from Franklin, Idalia, and Lee already this summer, so erosion issues will get a bit worse.


PTC 16 is expected to top out near 60 mph winds as it comes ashore this weekend. However, over a rather broad area, we should expect 30 to 40 mph winds, with gusts over 40 to 50 mph, basically from Myrtle Beach, SC to Montauk, NY. A smaller area near the center should see the 60 mph winds on the coast of North Carolina, should the system develop as expected.

Anywhere you see red color (basically northern SC through the Jersey Shore), wind gusts of 40 mph or stronger are likely. Peak winds, with gusts over 50 to 60 mph will occur between Cape Hatteras and Cape Fear in North Carolina, as well as in Pamlico Sound. (Pivotal Weather)

These winds will be capable of doing mostly minor damage, though scattered to numerous power outages are absolutely possible.


Total rain will be generally 2 to 5 inches, with isolated higher amounts up and down the coastal plain, extending inland in spots, particularly in Virginia and southeast Pennsylvania. Obviously this could cause flash flooding in spots. I would especially be aware of this rain on the coast, particularly in developed, more urbanized areas (Virginia Tidewater, Ocean City, MD, etc.) where the heavy rain could exacerbate tidal flooding by slowing how quickly it recedes at low tide. Some more considerable flash flooding risk probably exists near the center of this storm for Surf City to New Bern to Cape Lookout.

Rainfall on average of 2 to 5 inches will extend from portions of Southern New England south into North Carolina, extending a bit inland in portions of Virginia.

The bottom line is that this will be a notable storm on the East Coast with widespread impacts that will be disruptive and locally damaging.

Deep Atlantic wave (Invest 90L): Out to sea?

Yesterday, the Cabo Verde wave we’ve been watching was tagged as Invest 90L. We are slowly honing in on a compromise between the GFS and Euro solutions that I laid out in yesterday’s post.

We will watch trends today and tomorrow, but at this point, the odds will heavily favor a track that probably constitutes a “near miss” for the islands. It still needs to be monitored for obvious reasons, but the trends over the last 24 hours have been mostly positive for Puerto Rico and the islands. In this scenario if the system makes it into those areas, it would almost certainly be a weaker system.

Elsewhere, there is nothing of note out in fantasyland. For our Gulf of Mexico readers, yes, it still looks quiet.

September 21, 2023 Outlook: What do we make of the upcoming action in the Atlantic?

One-sentence summary

We discuss that the system off the East Coast this weekend will produce some notable coastal impacts, particularly from heavy rain and tidal flooding, and today we will assess the players that will shape the next Atlantic system near the Cabo Verde Islands.

Awaiting the next round of Atlantic action

Cabo Verde wave

Over the weekend, I noted how Hurricane Lee was emblematic of hurricane season, a marathon. You need to pace yourself to make it to the finish without losing your mind. Discussion about Lee lasted over three weeks, and it feels like we’ve already been sort of discussing this next Atlantic wave for about a week, and it’s just now awaiting the invest designation. This one has been a bit of a head scratcher, and we’re not a ton closer to resolution today on what will come of this. Let’s talk about what we do know.

Sometimes it makes sense to look forward before looking backwards. In other words, as a forecaster, sometimes I want to see what a model’s outcomes are before I go back and assess why it has that outcome. This is especially true when two of our more reliable models show two relatively different outcomes.

These maps show the GFS ensemble (L) and the Euro ensemble (R) and where their individual members place the tropical wave (then a defined system) next Tuesday afternoon. The background green shading indicates the IQR. Click to enlarge. (PolarWx/Tomer Burg)

In the map above, you can see the forecast IQR, or interquartile range difference of sea level pressure in the Atlantic from the GFS ensemble (L) and the Euro ensemble (R). Explain this to you like you’re three years old? You got it. You have operational models, which are the ones that are deterministic; one run, one solution. Then you have the ensemble models which are the ones that run the model roughly 30 (GFS) to 50 (Euro) different times with tweaks each time to produce a range of outcomes. The maps above show you what the ensemble model outcomes say for sea level pressure of the 75th percentile minus the 25th percentile. In other words, how spread out are the outcomes within the majority of ensemble solutions? Or are they spread out at all? This will illustrate key differences and/or areas of higher confidence.

The European model is fairly tightly clustered east or northeast of the islands next Tuesday afternoon with the tropical wave, or whatever it is at that point. The GFS at left is slightly less tightly clustered, more spread out, and also faster, with a couple members even almost in the Caribbean next Tuesday. Interestingly, the IQR differences are not substantially higher on the GFS than the Euro, which may be a bit of a red flag for the GFS. But we’ll note that in our back pocket and operate under the idea that there are noteworthy differences.

So, we look at this and say, “Ok…the GFS is quicker and potentially near the islands, while the Euro is slower. Why the difference?”

So we’ll next look up, about 20,000 feet at the 500 millibar level to get a sense of what is steering the wave.

The upper pattern over the Atlantic shows the GFS ensemble (L) with a weaker high and a faster developing system that gets to about 50°W longitude by Monday. The Euro ensemble (R) is slower overall and bigger with the high, so the wave only gets to about 45°W longitude. Click to enlarge. (PolarWx/Tomer Burg)

If we look at the forecast at 500 mb next Monday morning, we see the Euro and the GFS differ in terms of location and size of the high pressure system in the central Atlantic. The Euro is stronger and maybe actually holding the system up a bit. But the high pressure center moves out of the way, and an exit door into the open Atlantic awaits. Thus, the risk of the system making it into the Caribbean on the Euro is low.

But if you look at the GFS, the high is weaker, and a hair farther north, which probably allows the system to move a little faster, and it gets to the islands in some ensemble member cases before it can curve out to sea.

We can take this a step further to see which model develops the system faster. The GFS tends to be quicker to the punch than the Euro (forecast for Sunday morning shown here)

The Euro is slower with development of this wave and also farther north, while the GFS is much quicker to develop the system and is also farther south and west when it happens. These differences allow the system to get to the islands in some GFS ensemble cases but very few European cases. (Tropical Tidbits)

So what does all this tell us? The GFS is quicker to organize the wave, moves it faster west, and by the time the escape route north opens, the system may be bearing down on the islands. The Euro is slower, organizes the wave slower, and when the escape route opens, it’s still probably several hundred miles east of the islands and likely to hook northwest or north. Those are fundamental differences hinging on how the high develops and how the wave develops and interacts with other things surrounding it, questions we cannot adequately answer yet. But at least we have a cheat sheet of sorts now that we can apply to this wave. And we should know in a couple days if the islands are seriously at risk or if the northward solution is more likely. Stay tuned.

East Coast subtropical sloppiness

We continue to see a good chance that a surface low is going to develop well off the coast of Florida or Georgia tomorrow or Saturday. Look for that to wobble generally north up the coast and either into the Outer Banks or just ride up the East Coast toward Delmarva or the Jersey Shore as a subtropical storm or strong nor’easter.

An area of heavy storms offshore has a decent chance to organize into a relatively strong surface low and track north toward the Outer Banks or Sounds of NC, bringing impacts akin to a tropical storm or strong nor’easter. (

A subtropical designation just has to do with how the storm forms, and it has no bearing on the impacts. What will those impacts be? Well from the upper coast of South Carolina into most of North Carolina, coastal Virginia, Delmarva, and the Jersey Shore, we can expect rough surf, gusty northeast winds, moderate to locally major tidal flooding, beach erosion, and rip tides, in addition to heavy rain. This may be a step above nuisance status in some places now, akin to a rather strong nor’easter.

Tidal gauges from Virginia to New Jersey are currently forecast to experience moderate tidal flooding with this system, with even a handful of gauges in the lower Chesapeake Bay near the mouth of the James River expected to infringe on major flooding. (NOAA)

We are looking for a wide swath of 2 to 5 inches of rain on the Coastal Plain from Myrtle Beach through Long Island. This may cause flooding, particularly in lower-lying and urban areas. Coastal communities may see high tides exacerbated because of heavy rain, so this could slow the drainage process for a tide cycle or two this weekend.

Rain totals averaging 2 to 5 inches will spread from Myrtle Beach to Long Island in the coastal plain, with some inland spread in North Carolina and Virginia.

We will be keeping you posted on the East Coast storm, as well as the progress in the forecast of the Atlantic system through the weekend.