September 25, 2023 Outlook: Philippe and perhaps a friend will traverse the open Atlantic this week

One-sentence summary

Neither Tropical Storm Philippe or Invest 91L are expected to impact land at this time, but there are a couple other areas to keep tabs on beyond this week.

Happening Now: Philippe and 91L are not serious concerns

It’s the last full week of September, and in the Atlantic tropics we continue to pace ourselves with a couple storms per week. This week, we have Philippe, which formed over the weekend. We may add Invest 91L to the mix later this week, as it may have a window of opportunity to become Rina.

First, Philippe. While it has plenty of thunderstorm activity that it is maintaining this morning, it’s very clearly ragged looking, an indication that it is fighting off wind shear.

Tropical Storm Philippe is juiced up pretty good this morning, but it is clearly fighting off a good deal of wind shear. (Tropical Tidbits)

Philippe has 50 mph maximum sustained winds, but with the wind shear it is experiencing, it may struggle to intensify much beyond this over the next couple days. If Philippe can survive this stretch, there is some chance it may take a run at hurricane intensity by later in the week out over the open ocean, no threat to land. If Philippe succumbs to shear the next few days, it may actually stay on a westward course and get close to the islands. However, in that case, it would be unlikely to reintensify and impacts would be minor.

Tropical Storm Philippe is expected to hold its own over the next few days, eventually turning out to sea or falling apart northeast of the Lesser Antilles. (NOAA NHC)

So in terms of impacts in the Lesser Antilles, both a stronger Philippe and a weaker Philippe should make no difference. A stronger Philippe turns away faster and much farther east. A weaker Philippe tracks closer but falls apart.

Meanwhile, Invest 91L got tagged this weekend behind Philippe, and it is essentially following Philippe to the west. I’d expect a slow, gradual intensification this week and maybe an organized depression or storm by Wednesday or Thursday.

Invest 91L is expected to essentially follow Philippe to the west and north, though its ultimate outcome will be dictated by how strong it gets; stronger out to sea faster, weaker more south and westward but never organizing much. (Tomer Burg)

Ultimately, 91L’s future may be dictated (much like Philippe’s) by how strong it gets. A stronger storm would be apt to turn away from the islands quicker, whereas a weaker one would track closer but come with limited impacts. Either outcome produces minimal heartburn for the islands. We’ll keep track.

Finally, the NHC has highlighted an area in the far southeast Gulf with a 10 percent chance of development.

That seems reasonable right now. Wind shear is low for the moment, but it is expected to increase and expand over the Gulf this week, which should essentially shut down anything that tries to develop. So we are not worried about this one.

The medium-range (days 6 to 10): Eastern Gulf or East Coast shenanigans?

Could we do another Ophelia situation on the East Coast or even in the Gulf next week? The answer is maybe. Some modeling has hinted at a disturbance in the mid-levels of the atmosphere coming together somewhere around Florida, perhaps not far from where Ophelia developed last week. I think the ballet here is a little more delicate than it was last week, which would mean that we’d need a few more things to come together perfectly for this to happen. But if it were to do so, we could conceivably be talking about another tropical storm either in the Gulf or off the East Coast next week. Something for us to watch, but nothing I have enough confidence in today to say much more about. This is very much a stay tuned situation.

Fantasyland (beyond day 10): Still a bit noisy

I can’t hone in on anything specific right now, but in looking at all the modeling beyond day 10, I would think that we’re onto something, potentially in the western Caribbean. Again, I’m not certain that this will happen, but it’s the one place I’d be watching into mid-October. We’ll fill in the gaps on this as we get a little closer. It’s frustratingly vague to be sure, but that’s simply the reality of trying to forecast 10 to 15 days out.

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. (Weathernerds.org)

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.

Wind

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.

Rainfall

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.