Matt Lanza

September 26, 2023 Outlook: Beyond Philippe and Invest 91L riding its coattails, it’s tough to make much of anything else

One-sentence summary

Tropical Storm Philippe and Invest 91L in the Atlantic remain no serious concern at this time, and while things look to stay a bit active next week, it’s tough to say exactly what that means with any specificity.

Happening Now: Annoying Atlantic

We have Philippe, and we have Invest 91L that continue to churn in the Atlantic. Philippe has gotten virtually no stronger since yesterday. Invest 91L continues to have high odds of development, probably by tomorrow or Thursday.

Invest 91L is expected to essentially tail Philippe west, and while Philippe dissipates near the islands, 91L should be gathering some strength as it readies to curve northward. (Tomer Burg)

You can see from the map above how the track of Philippe is essentially trailed by the area of potential development from 91L, which is the red highlighted area. The intensity of each system will determine just how close it gets to the islands. The current thinking is that Philippe will dissipate north of the islands in the coming days. Invest 91L should take over as the better organized system, but even in the most extreme case, it would most likely pass north and east of the islands. Even if it did track farther south and west and closer to the islands, that would be due to a weaker system. So, it’s probably wise to keep watch on how this all plays out if you live in the northern Leeward Islands or Puerto Rico, but the vast majority of decent data seem to support a miss.

The medium range (days 6 to 10): Noisy near Florida

Early next week should be dominated mostly by what we see in the Atlantic. But as we get to the middle and end of next week, we have noise continuing to percolate in the modeling on either side of Florida. We’ve had some bizarre solutions printed out by modeling since the weekend, including systems backpedaling southwest from off the Carolinas to something in the eastern Gulf moving northeast across Florida and out to sea to some model solutions showing absolutely nothing whatsoever.

The forecast for the mid-levels of the atmosphere on the last 10 GFS model runs for next Thursday tell us absolutely nothing useful. (Tropical Tidbits)

I think that’s an important element of this. Usually when you have this kind of inconsistency and only tepid ensemble model support, you have enough justification to be skeptical that anything will occur. So while I think this is certainly a region to watch in the days ahead, the most likely outcome is probably that nothing of note happens. We’ll obviously continue to watch to see what evolves in the days ahead.

Fantasyland (beyond day 10): Noise but no signal

We’ve seen no change in modeling since yesterday with respect to the extended range period. There are signs of potentially something in the western Caribbean or southeast Gulf, but there’s no signal whatsoever to what is there. In other words, I see some ensemble members of the various models showing me signs of development, but I see no consistency and no real consensus yet.

Historical points of origin of tropical systems in the first third of October focus our attention on the Bay of Campeche and northwest Caribbean. (NOAA NHC)

Climatologically, that’s exactly where you would be looking in early October. So it’s not a surprise that that is what we’re doing. But until we see any kind of signal in this soup, there’s little we can say beyond “it’s worth watching.” Especially for the eastern Gulf or northwest Caribbean.

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.