September 19, 2023 Outlook: Assessing the race for Ophelia between the Cabo Verde wave and Southeast subtropical shenanigans

One-sentence summary

Two systems may try to develop late this week or weekend, a deep Atlantic Cabo Verde wave and a subtropical system off the Florida or Georgia coast.

Near term Nigel

Let’s clear the deck first. Nigel? Still out there.

Nigel has had to deal with dry air, which has led it to struggle some, and it also has a mammoth eye. (Weathernerds.org)

The stand out feature of Nigel is the size of its eye. It’s tough to specifically measure, but I am estimating this is about 40 to 60 miles across. Dry air has been a persistent issue for Nigel, and it seems to be impacting its intensity and holding it back from becoming more than a minimal hurricane. Nigel will continue to track northwest and then eventually north and northeast, out to sea, no threat to land.

The medium-range (days 6 to 10): Subtropical Southeast vs. Classic Cabo Verde

Two systems may enter. Both systems will eventually leave. The hope is that neither will produce any serious impacts to land. Let’s start close to home.

Southeast subtropical shenanigans

The general theme for this week will be: Upper low forms over Florida, drifts offshore to the east, undergoes a top-down process to form a surface low which may develop into a storm as it tracks north toward the Carolinas. It would probably be a subtropical storm, but the impacts would essentially be similar to a tropical storm, so I don’t want folks to get hung up on technicalities here. There will likely be a coastal storm this weekend that tracks north from Florida toward the Carolinas. Exactly where, how strong, etc. remains to be determined.

The impacts will probably include locally heavy rain, rough surf, possible beach erosion, and gusty winds on the South and North Carolina coasts.

Locally heavy rain in South Florida through the week that will spread north this weekend. Locally heavy rain is possible from the Carolinas up along the Jersey Shore toward southern New England this weekend. (Pivotal Weather)

The map above is a preliminary rainfall forecast through Tuesday morning. Florida gets their rain this week, locally heavy at times. As the system organizes that will spread north, certainly into the coastal Carolinas, but also perhaps up Delmarva, the Jersey Shore, Long Island, and southern New England. As of now, this looks like an early autumn nor’easter type impact. Although exactly what intensity the impacts of this system arrive with remains to be seen. We will have more on this tomorrow and Thursday.

Cabo Verde wave

The deep Atlantic is a little sloppy right now, but emerging from this mess will likely be the next wave off the coast of Africa. We continue to have model support for this to develop, however that support seems to have waned a bit since yesterday. The 70 percent chance of development assigned by the NHC is probably a good spot to be right now.

Anyway, this wave will come west over the next week or so and eventually end up near the Lesser Antilles or Puerto Rico. It may swing north of there, or it may enter the islands. It will be steered by high pressure over the central Atlantic.

High pressure near the Bahamas may help steer or orient the next Atlantic wave to either be tugged northward by the trough over the North Atlantic or sneak through as a lower-end storm into the Caribbean. Odds still favor a curve north. (Tropical Tidbits)

There is some chance that this high may build far enough west and south to perhaps block out the tropical wave or cause it to slow enough to be picked up by that trough in the North Atlantic. Odds probably favor that latter scenario in this situation. Still, I think in general this area merits watching because of the time of year, the warmth of the water, and the potential track. But it remains too early to say whether or not it’s a particularly serious concern for the islands. We’ll monitor it over the next few days.

Hopefully the most exciting aspect of these two waves will be who gets a name first, if either does. My bet is on the Southeast system today. The next two names are Ophelia (o-FEEL-ya) and Philippe (fee-LEEP).

Fantasyland (beyond day 10): Nothing brewing of note

We continue to keep an eye on the extended period to look for signs of trouble. As of now, it looks like things will be fairly quiet. Wind shear is expected to be well above average in the Gulf and northwestern Caribbean, which would be two key areas to watch in early October. So I’m cautiously optimistic that things will calm a bit, but as always we’ll keep watching.

September 18, 2023 Outlook: What is next in the tropical Atlantic pipeline?

A quick thank you to the new followers we’ve gained over the last couple weeks, especially in New England and Atlantic Canada! We hope you’ll stick around going forward as we continue to cover the Atlantic and eventually branch out into other significant and extreme weather later this autumn and winter. Spread the word!

One-sentence summary

Nigel is expected to swirl out to sea through the week, while we watch the next wave off Africa as perhaps making it a little farther west, as well as a potential lower-end system off the Southeast this weekend.

Near-term: Margot & Nigel

We’ll use this week to sort of recharge after 3 weeks of Lee, which was preceded by Idalia. This patterns can really take a lot out of you, and it’s important to pace yourself during hurricane season as a resident, forecaster, or decision-maker. At present, we’ve got one system out there and a second or even third that we’ll see toward the weekend.

Hurricane Nigel is the only active storm currently, but the large wave emerging off Africa is likely to develop this week. (College of DuPage)

Nigel is not a big deal in terms of impacts. It will likely become a major hurricane as it lifts north and eventually northeast. While Nigel will likely turn out to sea before affecting any land, it will probably (again) kick up surf for Bermuda. Nigel seems to fit the theme of the 2023 Atlantic hurricane season.

Hurricane Nigel’s forecast from the Hurricane Center with sea-surface temperatures highlighted in the background. Nigel has a couple days over very warm water to become a major hurricane. (Tomer Burg)

Meanwhile, Margot got the downgrade yesterday, losing tropical characteristics. It will meander in the eastern Atlantic for a few more days.

The medium range (days 6 to 10): Ophelia (?) in the Atlantic and watching the Southeast

The National Hurricane Center has tagged the next disturbance to move off Africa with about a 70 percent chance of development over the next 7 days. There’s a slight chance this could develop at the end of the near-term, but for our purposes, we’ll focus on this for the medium-range.

The forecast from the European ensemble for sea level pressure on Monday of next week shows a fair bit of uncertainty, much of which will be dependent on intensity of the next wave. Stronger outcomes turn north faster, while weaker ones will progress toward the islands. (Tomer Burg)

Anyway, this wave seems to have a decent shot at perhaps becoming a depression by about Thursday or Friday. This one has a little more uncertainty behind it in terms of track. If this thing can come out of the gate roaring and quickly develop, it will almost certainly follow Nigel or Lee or something in between and curve north quickly, avoiding the Caribbean islands again. If this disturbance struggles late this week and weekend and fails to organize, it will likely come west, with at least some chance of getting to the islands. It’s a little early to say much more about it than that, but it’s at least worth checking in on again Wednesday or Thursday to see what has happened. Really, the only thing we’ll be keeping an eye on the next couple days will be odds it develops quickly, which right now *seem* high, but you never can be too sure.

The other system to watch may or may not be a thing, but the NHC is giving it a slight chance to happen by the weekend. An upper level dip in the jet stream over the Southeast and Florida may allow a surface low to develop off the Florida coast by Friday or Saturday. If that happens, it will have a slight chance to develop into a tropical or (more likely) subtropical entity.

The forecast view 20,000 feet up between Tuesday night and next Monday evening shows an upper low (blue) develop over Florida. A weak surface reflection may develop leading to a tropical or subtropical low and lower-end system drifting toward the Carolinas this weekend. (Tropical Tidbits)

In all likelihood, it would probably track north, slowly, toward the Carolinas, and I would imagine that the intensity ceiling on this one would be fairly low. In other words, we’ll probably see slow, lower-end development, not rapid, high-end development. So, something to watch, but probably not something to fret much about. As of now, the vast majority of the rain associated with the upper low or potential system would be focused offshore. But any tropical system could kick the surf up again in this area, and we could see issues with beach erosion and such. We’ll keep you posted.

Fantasyland (beyond day 10): No specific concerns

I don’t necessarily have an opinion today on the long range portion of the forecast. I don’t see anything scary on any modeling, but I’m not actually convinced it will be quiet. So this is a true “punt” on the forecast right now. But the key point is nothing specific stands out right now. We’ll keep you posted.

September 17, 2023 Outlook: Au Lee-voir

One-sentence summary

Post-tropical cyclone Lee is on its way across the Gulf of St. Lawrence and should be completely out of the picture by tomorrow morning, tracking well south of Greenland.

Post-tropical Lee: 45 mph, moving NE 22 mph

We first started talking about Lee as it was about to become Invest 95L back in the closing days of August while Idalia was readying to impact Florida. When we say hurricane season is a marathon, not a sprint, this is what we mean. Now, mercifully after nearly 3 weeks of tracking, Lee is implementing its exit strategy across the Gulf of St. Lawrence and eventually out to sea.

The swirl from Lee is located just northeast of PEI this morning. (Colorado State RAMMB)

Lee’s center is off the coast of PEI and moving toward the Great Northern Peninsula in Newfoundland. Lingering tropical storm conditions will continue over PEI, portions of Nova Scotia, and Iles-de-la-Madeleine. Gusty winds are expected in Newfoundland, but impacts should be relatively minor. Rough surf will continue across Atlantic Canada, but any risk of damaging tidal flooding has diminished.

Rain totals were a bit spread out, but I found over 5 inches near Eastport, ME, almost 5 inches (125mm) near Fredericton in New Brunswick, and there were reports of around 100mm in Gaspe in Quebec and Grand Manan just east of Maine.

Nova Scotia power reports about 75,000 customers without power as of 11 AM (ADT), there are about 12,000 without power in New Brunswick, and about 40,000 in Maine.

That about closes the book on Lee.

Elsewhere

We’ll go into more detail on this tomorrow or Tuesday, but the rest of the Atlantic is busy but of no concern. For now. Nigel and Margot will not impact land, though Margot could brush the Azores as a remnant depression. The next wave, which the NHC gives a 40 percent chance of development over the next week is worth watching, particularly in the Caribbean, as there are questions as to exactly what the steering pattern in the Atlantic is going to look like when it gets there.

The next wave up will be worth monitoring, as the steering pattern in the Atlantic does not look as clear as it did for Lee, Margot, and Nigel to direct those systems north quickly. (NOAA NHC)

I would say the odds still favor a track north of the islands, but confidence in this is far less than it was for Lee, Margot, and Nigel.

Otherwise, there is at least reason to watch near Florida this week, as an upper low may develop in the neighborhood. While that seems unlikely to lead to a surface low developing, you never can be certain. Regardless, it means increasing rain chances for Florida and perhaps the Bahamas and Southeast. We’ll see how things evolve. More tomorrow.

September 16, 2023 Update: Lee bearing down on Maine and Canada

One-sentence summary

Lee is on track to deliver mostly expected impacts to Atlantic Canada and Maine today, with heavy rain ongoing in Maine, a 2 foot surge so far in Canada, and wind gusts as high as hurricane-force so far in portions of New Brunswick and Nova Scotia.

Hurricane Lee is arriving in the Canadian Maritime provinces this morning. (Weathernerds.org)

Hurricane Lee (now-post-tropical): 80 mph, moving N 25 mph

Lee was determined to be post-tropical, which means it’s now essentially a gigantic nor’easter instead of a tropically-derived hurricane. It means absolutely nothing other than a classification change. Impacts are identical to forecast.

Lee is flinging very heavy rain onshore in Maine right now, with a band of torrential rain between Fredericton, NB and Acadia National Park.

A band of torrential rain is moving ashore in Maine and portions of New Brunswick. (RadarScope)

Meanwhile, wind gusts have been ticking up around the region, with Grand Manan as high as 123 km/hr (77 mph), Halifax as high as 117 km/hr (73 mph), Mt. Washington, NH to 74 mph, St. John, NB to 85 km/hr (53 mph), Nantucket to 55 mph, and Eastport, ME to 62 mph.

The high tide cycle ongoing right now, as well as the next one this evening will be the highest for these areas. Yarmouth, NS is seeing about a 0.6m (2 ft) surge, Halifax 0.7m, and St. John about 0.5m. These are generally in line with expectations, maybe a smidge under. Surge of up to 1.5m (5 ft) is possible in Nova Scotia. With Lee’s center still technically south of Nova Scotia, the highest surge is yet to come. In addition, some potent waves will be coming ashore in Nova Scotia as well, with a buoy near Lee’s center at 8 AM AST reporting 30 foot waves.

So I think the takeaway here right now: Worst is over for southern New England, and it was handled pretty well as expected. Maine, particularly Downeast are in the height of the storm now, and it will wind down this afternoon. Nova Scotia, New Brunswick, and PEI will be in the height of the storm shortly if not already, and it will wind down tonight.

Elsewhere

Tropical Storm Margot may turn toward the Azores next week, while weakening and becoming a post-tropical cyclone.

Tropical Depression 15 should become Nigel today, if not by the next advisory. It is expected to become a hurricane out at sea, while re-curving east of Bermuda.

TD 15 should become Nigel very soon, and it will likely stay out at sea, away from land. (NOAA NHC)

Another potential Cabo Verde system may try to slowly develop later next week, but that is not a guarantee. The Gulf looks quiet, as does the Caribbean. Otherwise, things look generally quiet elsewhere too. We’ll let you know if that changes.