It’s not every day that the most formidable hurricane to threaten New England in 32 years lands right in your back yard. So when Hurricane Lee came knocking, we couldn’t help but to go chase it. There was much discussion comparing Lee to Hurricane Bob, which steamrolled Rhode Island and southeastern Massachusetts back in 1991. But despite the hype, Hurricane Lee ended up being a typical peak-season tropical cyclone for New England and the Canadian Maritimes.
Lee Made Landfall as a Category 1 Hurricane. Why Were New England and the Canadian Maritimes Largely Spared?
Both New England and the Canadian Maritimes got incredibly lucky in two areas that cause Hurricane Lee to largely spare the region. Yes, we can, and should breathe a sigh of relief after such a close call. However, while Lee was never going to be Hurricane Bob bad, it could have been much, much worse.
The Westward Wobble in Lee’s Track Occurred Over the Gulf of Maine Instead of Right Off Cape Cod
We all knew that once Hurricane Lee turned north, it would veer to the northeast before the Bermuda High pushed it back to the west. The big question was when those two wobbles would take place.
The models had been very consistent having Lee wobble west as it approached Cape Cod, driving the eye right into the Outer Cape. This scenario is what worried forecasters that Lee could deliver a punch Cape Cod has not seen since Hurricane Bob.
Thankfully, Lee moved north faster than anticipated. As a result, that westward wobble occurred over the Gulf of Maine, which kept the eye offshore of Cape Cod. Even better, it actually wobbled east as it passed Cape Cod, pulling it even further away from the Cape. The two wobbles were almost timed perfectly enough to bend Lee around Nova Scotia, too. The eye barely clipped Long Island, Nova Scotia before making landfall near Fundy National Park in New Brunswick.
Lee was Transitioning From a Hurricane to a Post-Tropical Cyclone as it Passed Over New England and the Canadian Maritimes
Whenever a tropical cyclone transitions to post-tropical, it loses its tropical characteristics and becomes a mid-latitude cyclone. During the transition period, its warm core collapses, which effectively makes the storm coast on its own angular momentum or rotation until the jet stream fully absorbs it. To demonstrate this phenomenon, take a glass of water and stir it with a spoon so you get a nice whirlpool at the center. Then remove the spoon. The whirlpool will spin on its own for a while before dissipating. Removing the spoon is the equivalent of the hurricane’s warm core collapsing.
The timing of Lee’s transition from tropical to post-tropical could not have been more perfect for New England and the Canadian Maritimes. The transition began is Lee approached Cape Cod. While Hurricane Lee had lost most of its tropical characteristics before it made landfall in Canada, the jet stream didn’t fully absorb it until it was over the Gulf of St. Lawrence well north of Prince Edward Island. From an intensity standpoint, Hurricane Lee coasted over New England and the Canadian Maritimes on its own energy. As a result, other than some downed trees and power outages, Lee did minimal damage throughout the entire region.
Grading Our Forecast: How It Performed as Hurricane Lee Made Landfall in Canada
You’d think being such a massive storm, Lee’s impacts would have been easy to predict. In fact, it was quite the opposite. With so many moving parts seemingly tangled up in each other, Lee was a particularly tricky storm to forecast. It required us to consider questions that included:
- What was its predicted forward speed?
- When would it take its two wobbles, one east and one west?
- To what extent and speed would the wind field expand?
- How quickly would it weaken, based on both water temperatures and wind shear?
- Where would the steering currents set up?
- How much of an influence would each steering current have on the hurricane?
- When and how fast would it transition from a hurricane to a post-tropical cyclone?
Further compounding the matter was Lee’s surprisingly tight wind gradient, particularly over southeastern New England. That meant that the timing of Lee’s wobbles would make a huge difference in the wind speeds. A 50-mile (80 km) deviation in track ultimately meant the difference between Cape Cod getting hurricane-force winds and it not even seeing sustained winds reach tropical storm force.
The Track: Where Lee Made Landfall
While we didn’t quite get the timing of the wobbles right, we were correct in forecasting that Hurricane Lee would slalom east and then west before making landfall near the US-Canada border. We gave it a 50/50 chance of clipping southwestern Nova Scotia. Hurricane Lee ultimately clipped Long Island in far southwestern Nova Scotia before making landfall near Fundy National Park in New Brunswick, about 100 miles (160 km) from the international border.
The Hard Numbers: How We Did in Our Wind Forecast
There were certainly two sides to this story. On one hand, most of our sustained wind forecasts were either correct or within 5 knots of being correct. Furthermore, we only missed two predictions for the timing of peak winds. And those were for the two furthest points from Lee’s track: New York City and St. Pierre et Miquelon.
But the wind gusts really got away from us. With a couple exceptions, we flagrantly overestimated Lee’s gusts. We’ll circle back to why we got them so wrong, but here is how we did so you can judge for yourself.
| City/Town | Forecast Max Sustained (kt) | Observed Max Sustained (kt) | Forecast Max Gust (kt) | Observed Max Gust (kt) | Data Source |
|---|---|---|---|---|---|
| New York, NY | 15 to 25 | 18 | 25 to 35 | 25 | National Weather Service |
| Montauk, NY | 20 to 30 | 15 | 35 to 45 | 26 | National Weather Service |
| Newport, RI | 25 to 35 | 23 | 45 to 55 | 33 | National Weather Service |
| Woods Hole, MA | 35 to 45 | 35 | 55 to 65 | 45 | Weather Underground |
| Chatham, MA | 40 to 50 | 23 | 60 to 70 | 53 | NWS/Wx Underground |
| Boston, MA | 30 to 40 | 28 | 45 to 55 | 41 | National Weather Service |
| Portland, ME | 30 to 40 | 32 | 50 to 60 | 44 | National Weather Service |
| Bar Harbor, ME | 40 to 50 | 25 | 60 to 70 | 39 | National Weather Service |
| St. John, NB | 40 to 50 | 35 | 60 to 70 | 44 | NWS/Env. Canada |
| Yarmouth, NS | 50 to 60 | 33 | 60 to 75 | 46 | Environment Canada |
| Halifax, NS | 35 to 45 | 38 | 55 to 65 | 73 | Environment Canada |
| Charlottetown, PE | 25 to 35 | 29 | 45 to 55 | 36 | Environment Canada |
| Gaspé, QC | 25 to 35 | 16 | 35 to 45 | 23 | Environment Canada |
| Port aux Basques, NL | 25 to 35 | 35 | 45 to 55 | 42 | Environment Canada |
| St. Pierre et Miquelon, FR | 20 to 30 | 26 | 35 to 45 | No Data | Météo France |
We do want to point out one data anomaly in the table above. While the Yarmouth, Nova Scotia airport only saw a peak gust of 85 km/h (46 kt), Environment Canada reported gusts over 100 km/h (54 kt) all over southwestern Nova Scotia. Those gusts would put the Yarmouth area close to or within our forecasted 60 to 75 knot range.
Why Were So Many of Our Wind Gust Forecasts Wrong?
Put aside the fact that wind gusts are notoriously difficult to predict, even in the best of times. As Lee transitioned from tropical to post-tropical, it encountered heavy wind shear as the jet stream began to absorb it. As a result, nearly the entire top of the hurricane was sheared off. Combined with the warm core of the hurricane shutting down as it transitioned to a post-tropical cyclone, winds aloft were far weaker expected. The majority of wind gusts in any storm coming from winds aloft mixing down. With less wind to mix down, the end result is that we overestimated many of our wind gust forecasts.
Additionally, wind speeds are dependent on the track of the hurricane. In the table above, we grossly overestimated both the sustained winds and the gusts in Bar Harbor, Maine and Gaspé, Québec. Those overestimations are a result of Lee tracking further away from both of those locations than expected.
The Verdict
Given the complexity of Hurricane Lee, I’ll give our forecast a B. Yes, the heaviest weighted parts of the forecast – timing, sustained winds, and track – we for the most part got right. However, the combination of wind shear and Lee transitioning to a post-tropical cycle knocked the wind gusts down a lot more than many people expected.
Both New England and the Canadian Maritimes dodged a bullet with Hurricane Lee. Major hurricanes have hit both New England and the Maritimes before. They will strike again. Next time, we may not be so lucky.
