September 13, 2023 Outlook: Lee starting to make its turn north toward New England and Nova Scotia

One-sentence summary

Hurricane Lee is slowly starting to weaken, but remains a large and powerful hurricane as it turns northward on Wednesday morning and it will eventually bring significant impacts to parts of eastern New England and Atlantic Canada this weekend.

Current status of Lee

As of 8 am ET on Wednesday morning, Lee has sustained winds of 115 mph and is moving to the northwest at 6 mph. In terms of timing, it will bring impacts to Bermuda starting late tonight through Friday, and then into New England and Atlantic Canada by later on Friday and Saturday. By that time Lee will be weakening, but should still pack a punch given its large size.

Lee track forecast

Our confidence in where Lee will go over the next couple of days is high. After turning today it should move more or less north, passing to the west of Bermuda. A tropical storm warning is in effect for the island due to the threat of heavy rainfall and strong waves. However, Bermuda thankfully should be spared the worst effects of Lee along this track.

Super-ensemble forecast for Hurricane Lee, with annotation. (Tomer Burg)

After days of uncertainty, we should finally start to get some clarity today on Lee’s track at the end of this week, and its implications for residents of New England and Atlantic Canada. At this point I’m leaning toward a northward track until Friday, at which point the storm should make a dogleg to the left. Our main forecast question, in regard to track, is how significant will this westward bend be? It depends on the strength of a trough of low pressure over the Pennsylvania and New York region.

Our best hurricane and global models indicate that this turn will bring the center of Lee fairly close to the Cape Cod region of Massachusetts early on Saturday morning, although the storm is still expected to remain largely offshore. The center would then move into coastal Maine by Saturday night or Sunday morning. The center would subsequently move through Atlantic Canada and make its exit to the northeast. Again, we should get a better handle on the details of this dogleg over the next 24 hours, and we’ll have an update for you late this afternoon.

Lee intensity forecast and impacts

Lee now faces a number of factors that should lead to a gradual diminishment in strength, including increasing wind shear and a track that will bring it over cooler seas. However, this process should be slow, and it is likely that Lee will approach Cape Cod and Maine this weekend as a broad, Category 1 hurricane. As it likely will be starting to transition into an extratropical storm, you can probably expect the storm to behave more or less like a very large nor’easter.

Forecast for maximum wind gusts from Hurricane Lee this weekend. (Weather Bell)

After bringing tropical storm impacts to Bermuda, Lee could start to bring Tropical Storm-force winds to the Cape Cod area of Massachusetts by Friday night, and into Maine and Nova Scotia by Saturday morning. How strong will these winds be? That will depend ultimately on the storm’s track and how much its intensity wanes, but the following wind gust forecast from the European model offers a decent representation of risk. Note that wind gusts are short bursts of wind, and that sustained winds will be lower.

Rainfall totals are likely even less predictable than winds, because they’re not only dependent on track but also more localized conditions that will determine where thunderstorms train. The heaviest totals are likely accumulate in Maine and Nova Scotia, where some areas may see 3 to 6 inches of rainfall in a fairly short period from Lee.

Hurricane Lee rainfall totals. (Weather Bell)

There will, of course, be myriad other effects from this storm. One of them is storm surge. We have seen in the past the larger hurricanes tend to produce a more significant surge of water, and it appears as though Lee could bring a pretty significant coastal surge event into Maine and parts of Canada. The details of this will be worked out in the next day or two as we fine-tune the track forecast. Accordingly, Beach erosion, rough surf, and rip currents are a lock for the East Coast and Atlantic Canada. Not a good beach weekend, to be sure. Areas that see stronger winds and rainfall will likely see downed trees, which could in turn knock down power lines. So be prepared for some disruptions of that kind, as well.

Hurricane Margot and the rest of the gang

Margot is a hurricane at sea. Fortunately there is nothing to see. After spinning and going whee. In a few days, it should cease to be.

Beyond Margot there is another system that is very likely to develop into hurricane over the next several days. This system is probably not a concern for the continental United States or Caribbean islands, but could definitely be something for Bermuda to watch. If so, impacts would occur about a week from now, or maybe a bit longer. But we have a lot of questions to answer before getting into a specific forecast for a storm that would be called Nigel, should it form.

Nigel-to-be will split the uprights between Lee and Margot, most likely. (National Hurricane Center)

Look for our next update on Lee late this afternoon.

Tuesday PM Lee Update: Bermuda under a Tropical Storm Watch, as Lee’s wind field grows larger

One-sentence summary

Hurricane Lee will impact Bermuda with tropical storm conditions in a couple days, as Lee’s wind field now extends out nearly 250 miles from the center.

Lee will turn northward tomorrow or Thursday, passing west of Bermuda and tracking toward eastern New England or Atlantic Canada. (NOAA NHC)

Hurricane Lee: 115 mph, moving NW 7 mph

What’s changed since this morning?

Bermuda is now under a Tropical Storm Watch, with Lee expected to bring some impacts to the island in a couple days.

The forecast track this weekend continues to wobble a bit between Maine and Nova Scotia. While impacts will extend far from the center of Lee, the actual track does matter in terms of what to expect from storm surge. This will need further fine tuning.

Lee is growing in size, with tropical storm force winds extending out nearly 250 miles from the center.

Bermuda impacts

Expect very rough surf, a period or periods of rain, and gusty tropical storm force winds on Bermuda. Tropical storm force winds should arrive Thursday afternoon at the latest I’d think with rain reaching Bermuda by late Thursday morning or early Thursday afternoon.

Lee’s forecast focus: Rain

Let’s talk a little about rain. The good news with Lee is that it will be moving quickly. There have been and will continue to be some rains in Maine and portions of eastern New England this week, as well as in New Brunswick. When Lee marches into Maine or Nova Scotia, there will be rain spread all over, but there will be a core of rain that could be a bit troublesome. The GFS, which tracks Lee into Nova Scotia brings that 4 to 8 inch (100-200 mm) core of rain mostly toward Nova Scotia or into the Bay of Fundy. The European model, which tracks Lee into Downeast Maine brings it toward Acadia National Park and Bar Harbor. Also notice on the maps below that there are significantly different rainfall forecasts between the Euro and GFS for Massachusetts as well. The Cape, Islands, and Boston see heavier rain from the Euro, while the GFS delivers only some rain to the Cape. New Hampshire also sees differences here too.

Click to enlarge the rainfall forecast (from Lee, not including rain this week) for Maine and New Brunswick which shows the differences between two operational models in terms of where the heaviest rain may fall, relative to track. (Weather Bell)

This trend actually holds up within the model ensembles right now as well. The European model tends to bend back to the west a bit toward Maine and New Brunswick, while the GFS ensembles are placed more to the east, aiming at Nova Scotia.

Click to enlarge a map showing the spread between the European and GFS ensemble model members. The red hues on the left indicate that the European model ensemble has more members suggesting a track that could lurch toward Maine or New Brunswick, while the GFS is focused more on Nova Scotia. (Tomer Burg)

Interestingly, the European model has the support of the new HAFS-B hurricane model, which does currently show the storm clipping Massachusetts before coming in over Bar Harbor. The HWRF, our previous top hurricane model shows the storm coming in near Yarmouth, NS. So to say we’re confident in which camp is right would be lying. However, the HAFS-B has had a bit of a hot hand lately, and when I see the Euro and a top hurricane model on the same page, it makes me believe a track closer to Maine may be slightly more likely than the alternative. We’ll see.

The bottom line in all this remains that folks on Cape Cod, Nantucket, Downeast Maine, New Brunswick, and Nova Scotia should be preparing for heavy rain, wind, and tidal impacts from a hurricane this weekend. Please, again, don’t assume that just because Lee is weakening on approach that that makes it worth downplaying. As I noted this morning: Lee will punch well above its weight class when it comes ashore. The size of Lee means that it will be bringing a significant amount of water north with it, and that will cause surge/coastal marine impacts equivalent to a much stronger storm than Lee may be classified as.

We’ll have more in the morning.

September 12, 2023 Outlook: Lee will take aim at New England and/or Atlantic Canada this weekend

One-sentence summary

Although Hurricane Lee is expected to weaken as it comes north, it will be expanding in size and capable of punching above its weight class as it brings impacts to eastern New England and/or Atlantic Canada this weekend.

Hurricane Lee: 115 mph, moving WNW 7 mph

What’s changed since yesterday?

Lee’s track forecast is slowly clearing up, with confidence increases in both timing and broad track today. We can now say that Lee will likely take aim at New England or Atlantic Canada or both regions this weekend.

Hurricane Lee will slowly weaken over the next few days as it turns and accelerates to the north, however it should run into coastal New England or Atlantic Canada as a large storm this weekend. (Tomer Burg)

Lee’s track forecast

The forecast for Lee’s path is becoming a bit more straightforward now, but there are still some modest differences we need to sort out.

Click to enlarge the track density forecast. Good agreement through about days 3-4 which brings Lee west of Bermuda. Then, although we expect Lee to broadly track to New England or Canada, the specifics are more challenging. (Tomer Burg)

There are two camps now, with one generally proceeding straight north or north-northeast toward Nova Scotia and the other straight north or even bending back northwest toward Maine. These differences may seem minor, and they are to some extent, but they will determine where the worst of Lee’s surge goes and where the worst weather will occur. Historically, there is little precedent for a storm striking the Maine coast from the due south or southeast. Most either arrive from southwest, paralleling the coast or make landfall from the south-southwest. Unique storms have unique impacts. So sorting out the finer details of Lee’s track will allow the impacts to become clearer. If Lee tracks toward Nova Scotia, that’s a more frequent impact zone, and while Lee would certainly be a significant storm there, there is at least some precedent for that.

Lee’s intensity forecast

This part of the forecast is actually a little easier I think. Lee should slowly weaken in the coming days to either a category 1 hurricane or strong tropical storm as it makes landfall wherever. However, because of Lee’s size and intensity and its transition from a tropical storm to more of an extratropical feature (think: very large nor’easter), it will act stronger than what it actually is. In other words, it’s important to recognize that a weakening storm is still a serious storm in this part of the world. And Lee checks the boxes for a potential serious hazard to folks in Canada and New England, even in a weakened state. Tropical Storm force winds extend out almost 200 miles from Lee’s center, so while the exact landfall point will matter for some aspects of Lee, the impacts will extend far from the center.

Lee’s impacts

We’re still honing in a bit on this area of things, but let’s share what we know today.

For Bermuda, it seems that Lee will pass to the west by 100 miles or so, which should be plenty close to deliver tropical storm impacts, and I’d expect Tropical Storm Watches to be issued there today. Additionally, Bermuda will probably see some heavy rain, very rough surf, beach erosion, and rip currents as Lee approaches.

Looking elsewhere at impacts: First, beach erosion, rough surf, and rip currents are a lock for the East Coast and Atlantic Canada. Swimming probably won’t be recommended this weekend anywhere from the Mid-Atlantic northward.

Significant wave heights will be substantial up and down the East Coast this week, leading to dangerous surf, rip currents, and potentially some beach erosion. The forecast above is for Friday evening, with Lee due east of Norfolk, VA. (Weather Bell)

Second, and one area of concern: Rain. Lee’s exact track will determine who sees the heaviest rainfall from the storm. However, with periods of heavy rain likely this week across New England, and some antecedent ground conditions in coastal Maine, New Hampshire, and Massachusetts already wetter than normal, tropical rainfall won’t be ideal.

The rain forecast through Thursday evening in northern New England shows anywhere from 1 to 2 inches of rain or a bit more in spots, meaning additional 2 to 4 inches or so of rain from Lee may cause some flooding issues, particularly in Maine and New Brunswick. (Pivotal Weather)

Flooding is one concern obviously, but so will downed trees due to saturated soils and gusty winds. In other words, it won’t take a hurricane in some spots to knock down trees or power lines. The good news in all this is that Lee should be accelerating north as it passes through which will limit the rainfall potential a bit and hopefully avoids serious freshwater flooding concerns.

Wind, as noted, will be an issue as well for obvious reasons. We’ll hone in on that aspect of things as we get closer.

And last but not least, storm surge. Lee will be bringing a fair bit of water north with it as it heads toward Canada or New England. As a result, depending on the exact track of the storm, this could come roaring ashore on the coastline near and right/east of the center. It’s a bit soon to talk about how bad that could be, but given Lee’s larger size, it seems reasonable to think a pretty significant coastal surge event could unfold in Canada or New England.

Guidance based on the GFS model shows about 2 feet of surge arriving in Nantucket on Friday. We can hone in on more specifics for this as we get closer to the weekend. (NOAA)

We will fine tune these impacts as we get closer to the storm. In the meantime, it’s the right time to begin preparations in coastal eastern New England and coastal Atlantic Canada. While the details are still a bit uncertain, the likelihood of potentially significant impacts is increasing.

We will have a brief update later this afternoon, followed by a full update Wednesday morning.

Elsewhere: Margot makes five

Meanwhile, congratulations are in order for Margot, which became the season’s fifth hurricane. It remains unlikely to impact land. Winds are 85 mph this morning.

Behind Margot, we continue to see signs that the next wave will develop in the coming days. Invest 98L is expected to form and track west, then northwest across the Atlantic. It appears likely to go north of the Caribbean islands, but given how much time we still have ahead of us for this one, it remains worthy of continued watch. This one has ruffled a few feathers as some operational guidance shows it getting close to the U.S. at times in the 11 to 15 day period. Frankly, that’s way too far out to proclaim anything one way or the other, but when looking at ensemble guidance, it appears those dramatic solutions are presently significant outliers and unlikely to materialize. Plenty of time to watch.

September 11, 2023 Outlook: Lee turns north this week, with an out to sea escape scenario becoming increasingly unlikely

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One-sentence summary

Hurricane Lee should peak once again today or tomorrow before beginning a weakening trend but also a period that has it grow in physical size as it comes north, increasingly unlikely to turn out to sea.

Hurricane Lee: 120 mph, moving NW at 7 mph

Lee is wobbling between WNW and NW motion, which should continue through midweek before a more decisive turn north, passing west of Bermuda. (Tomer Burg)

What’s changed since yesterday?

Lee has re-intensified to a Category 3 hurricane with winds of 120 mph. It is expected to peak once more in intensity today or tomorrow before beginning a gradual weakening trend as it encounters more shear and cooler water temperatures. Lee’s track forecast continues to flop around some, keeping eastern New England through Atlantic Canada on guard for potential direct impacts late this weekend.

Lee’s intensity forecast

Lee is by no means a perfectly healthy storm, but it has gotten some of its act together since yesterday.

Sunrise on Hurricane Lee this morning shows a storm continuing to fight off shear and some dry air, trying to intensify further. (Weathernerds.org)

Lee became a category 3 storm again yesterday, and it’s likely in the middle of a gradual intensification cycle that should peak today or tomorrow. After that, Lee begins to encounter cooler water and more wind shear from an approaching upper level trough in the jet stream which should allow for steady weakening.

It’s important to note that just because Lee is unlikely to be a major hurricane at high latitudes, it does not mean that Lee will not be a significant storm. Its wind field is likely to expand as it comes north. So it will compensate for weakening by growing in physical size. Folks potentially in the path of Lee should continue to watch it closely.

Lee’s track forecast

It’s becoming increasingly unlikely that Lee is going to turn out to sea. Over the next 2 or 3 days, Lee will track generally west-northwest or northwest, before turning northward. Lee will be steered around the western flank of weak high pressure in the Atlantic and toward a trough moving through New England.

The upper level map on Thursday morning shows some of the things we’ll be watching to determine where Lee ends up, but the “out to sea” solution is becoming increasingly unlikely. (Tropical Tidbits)

The trough is going to play an increasingly important role in Lee’s future, with the exact intensity of it this weekend up for some debate. That will determine if Lee is captured closer to New England or more toward Atlantic Canada. That may also determine how big, broad, and strong Lee’s wind field is when it gets there.

Lee’s track forecast spread has actually *widened* a little since yesterday, but confidence in a track, loosely somewhere between New England and Newfoundland is increasing. (Tomer Burg)

The bottom line at this point: Folks from eastern New England to Newfoundland should be closely monitoring Lee’s progress. Any direct impacts from Lee are likely to not arrive until Saturday if it tracks toward New England or early Sunday if it tracks toward Atlantic Canada.

Potential impacts through midweek

In the meantime, we have rough surf and rip currents that are expected to overspread most of the western Atlantic this week. This will impact most areas in the Bahamas, Turks and Caicos Islands and north facing shores of Hispaniola, Puerto Rico, and the Leeward Islands. Bermuda will also see this occur, but we’ll be watching to see there just how close the core gets to the island. For now, I would anticipate we’ll see Tropical Storm Watches hoisted for Bermuda by late tomorrow or Wednesday.

Elsewhere: Margot and what’s next?

Tropical Storm Margot is likely to become a hurricane today as it moves generally due north. It will not impact land over the next 5-6 days, but it may get tied up in awkward steering currents in the open North Atlantic that could lead to it wandering about well into next week.

Margot is likely to become a hurricane tomorrow as it tracks north. Eventually it will slam on the brakes and probably meander for a bit west of the Azores. (Tomer Burg)

Off Africa, the next system seems most likely to follow (broadly) Lee’s track, which hopefully keeps it north of the Caribbean and eventually turns it out to sea. It will merge with Invest 97L. I’m not sure if the protocol will be to tag it as Invest 98L or keep the 97L label, but whatever the case it comes broadly west-northwest through the week, and the vast majority of model guidance keeps it north of the Caribbean.

Other than that, we see absolutely no signs of any Gulf or Caribbean activity through midweek next week, with wind shear mostly ripping in that part of the basin.