The Eyewall

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.

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.

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.

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.

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.

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.

Just a quick note: We are aware of some email issues some of you are having where you get the post title and no other content. We’re investigating the reasons that may be causing this and hope to have a resolution soon. Sorry for any inconvenience!

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

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.

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 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.

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.

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.

One-sentence summary

While the final forecast for Lee is no clearer today than it was previously, there are some signs that we can begin to hone in on a region more likely to see Lee eventually.

Hurricane Lee: 105 mph, moving WNW 9 mph

What’s changed since yesterday?

Lee has continued to have to battle shear, and as a result it has weakened back to a category 2 storm with 105 mph winds. Lee has also slowed its forward speed down as expected by about 5 mph versus yesterday.

Everything else is mostly on track as forecast.

Lee’s intensity forecast

I had sort of expected to see that Lee would organize a bit more yesterday evening, but that failed to materialize. Modeling suggests that shear may relax a little over Lee, but I’m wondering if that ever happens. The direction of the shear may change, which could, I guess, lead to some readjustment on the intensity outlook here. In general, modeling forecasts intensification again over the next 2 days or so before a slow weakening trend. Lee will probably compensate a bit for weakening by growing its wind field over the next week as it goes north.

Lee’s track forecast

I’ll preface this by saying that confidence in Lee’s final outcome isn’t higher today than it was yesterday. However, there have been a few trends worth noting. First, the forecast track of Margot seems to have come into better agreement among models since yesterday, taking it more straight north than north-northwest. This tends to reduce the odds of an interaction with Lee. Perhaps one less variable in the equation then.

Second, there seems to have been a bit of a boost in agreement in Lee’s track as it comes north, or what I would say is “less spread” in the track. We now have ensemble modeling in moderate agreement on a track aimed broadly toward Nova Scotia late.

Now, a few big things to note here. First, just because we now have moderate track agreement toward Nova Scotia does not mean a.) that Nova Scotia is the target for Lee when it comes north or b.) that impacts will not be felt far outside that track. The ultimate track of Lee continues to bounce around in both time and space. The timing differences have narrowed a bit today along the track of Lee, which means by tomorrow or Tuesday we can probably peg the timing of impacts a bit better. Secondly, while most modeling broadly points it to between Downeast Maine and Nova Scotia, it does not mean that Cape Cod or Newfoundland can unplug here. There is still a wide array of tracks and options, including a handful that try to nudge it back northwest toward even Long Island or southern New England.

So, we’ve been slowly “clearing” places from Lee, and I think today that may include North Carolina. Modeling shows this staying well east of North Carolina now, so from there south to Florida, this isn’t your storm. Bermuda? Still needs to watch closely. I would probably continue to watch this from Virginia to New Jersey, watching it fairly close from Long Island through Rhode Island, and watch it very close between Cape Cod and Newfoundland, including New Brunswick and Prince Edward Island.

Again, no one knows for sure where Lee will go. The best we can do is gradually narrow the focus a little. In the meantime, expect rough surf and rip currents to be prominent issues in the Bahamas, Bermuda, and up and down the East Coast this week. More on Lee tomorrow.

Margot and 97L

As I noted above, Tropical Storm Margot’s track is coming into better focus today. Margot is expected to go basically due north or maybe just slightly west of due north over the next several days. It is also expected to become a hurricane.

Margot is still not expected to impact land.

Behind Margot, we have now established the new Invest 97L, which is located just west of the Cabo Verde Islands. Some operational modeling has gone wild with this one, bringing it to the Gulf or up the East Coast. We continue to not really see that as a major concern right now. We’ll keep tabs on 97L, but the odds of developing are only around 30 percent or so in the meantime.

Otherwise, the Gulf and Caribbean continue to look quiet for the next 7 to 10 days or longer.

One-sentence summary

Hurricane Lee will continue off to the west-northwest before turning northward east of the Bahamas/Turks & Caicos and heading off the East Coast and to the north.

Hurricane Lee: 115 mph, moving WNW 12 mph

What’s changed since yesterday?

Lee has fluctuated back down to a category 3 hurricane, but there are some indications that Lee may be beginning another cycle of intensification today. Fluctuations up and down in intensity are expected over the next several days.

Lee’s intensity forecast

As noted, Lee has ebbed to a category 3 storm with 115 mph winds. It does seem as if it wants to begin another cycle of intensification, however, and the official NHC forecast brings it back up to a category 4 storm tomorrow or Monday. Lee is battling some wind shear right now, and it has taken on a rather ragged look, but per the most recent discussion from the Hurricane Center, it’s pretty evident that Lee still has plenty of punch. Reconnaissance flights were unable to get into the northeast eyewall of Lee this morning due to safety concerns around the thunderstorm activity in that part of the storm.

The shear is sort of a wild card with Lee right now. If it holds on more than forecast, Lee may sort of oscillate between category 2 and 3 intensity over the next few days. If the wind shear can relax enough, Lee would be capable of intensifying again back to category 4 or so. The NHC has taken this into account in their forecast, which shows some strengthening in the near-term, followed by a drop in intensity late.

Regardless of “what” Lee is, it will remain a potent storm over the next 5 to 7 days. Rip currents and rough surf will be a feature along the U.S. East Coast, Bermuda, the northern Caribbean islands, and the Bahamas. Eventually the rough surf will make it to Atlantic Canada as well.

Lee’s track forecast

Everything is in line with what has been expected through early next week, which is to say that Lee should comfortably avoid the Caribbean islands and avoid the Turks and Caicos Islands as well. While there is still a bit of uncertainty on exactly where Lee will turn northward, there is *strong* model agreement that it will occur before Lee gets close enough to bring direct impacts to the southeast Bahamas and Turks & Caicos Islands.

If you live in Florida, you remain in the clear from Lee and do not need to worry about this storm. Easier said than done, I know, but no reliable modeling shows Lee coming remotely close to making it that far west.

Farther up the East Coast, we have little to no additional clarity today on Lee’s future track. The good news I guess is that we do have confidence that Lee will turn northwest, north-northwest, north, and eventually north-northeast. But exactly how that happens remains to be seen and everyone from about Delmarva through Atlantic Canada, as well as Bermuda should be continuing to monitor Lee’s progress.

The map above shows track density, or roughly how many of the dozens of ensemble members agree on where Lee will go. Notice that the confidence is actually moderate that Lee will turn north and end up somewhere west of Bermuda. But from there, confidence drops.

One of the biggest problems right now is timing. We know Lee will slow down once it gets just east of 70° longitude. How fast does Lee come north? There is significant, massive model disagreement on timing of that speed once the turn gets made. For example, the European ensemble’s 51 members (not shown) have the center of Lee anywhere between just east of Cape Hatteras to north of Prince Edward Island next Saturday. That is roughly a 1,000 mile along-track spread. So we have high confidence in the turn, high confidence that it will go northward and pass just west of Bermuda but low confidence in how quickly it goes north, and that has implications on what to expect if you live in Halifax or Boston or Montauk.

I will say, it appears that the threat of direct impacts is fairly low right now from Long Island into the Mid-Atlantic. You should still monitor things, but the consensus view of modeling is that Lee will pass to the east of the areas hard hit by Sandy. New England? A slightly different story, as there is still a good deal of modeling bringing Lee close to Cape Cod or the islands. Still, most of it keeps it east, but it’s close enough. Maine and Nova Scotia into western portions of Newfoundland may be most at risk in the current environment. Again, the timing and intensity and exact track are impossible to nail down right now. But you can plainly see above that modeling is skewed right now toward the Maritime provinces.

We’ll continue to keep you posted.

Elsewhere: Margot and the MDR

Tropical Storm Margot continues to plod along in the open ocean.

Margot has a good bit of warm water to work with over the next 3 days, so it should intensify close to hurricane strength before it approaches the cooler waters of the North Atlantic. Margot remains a bit of a wild card in terms of Lee’s track and we’ll likely be talking a little more about this storm later next week.

There continue to be some hints of another wave emerging off Africa and trying to make a go of it in the Atlantic Main Development Region (MDR) next week. As of now, there is not much else to say about that storm except that we are likely to see some outlier solutions on operational model guidance, so try not to read into that too much. Most reliable data says that this will be a slow developing system and may even struggle some.