Sept. 15 marks the historical peak of hurricane season, and it comes as no surprise that a massive, sprawling Category 1 hurricane is lurking just off the Eastern Seaboard. Lee, a long-lived hurricane that became the season’s first Category 5 exactly a week ago, now has 80 mph winds, and it has prompted warnings in New England ahead of its weekend arrival.
Tropical storm warnings are up from Westport, Mass., all the way to the Canadian border, including Cape Cod, Nantucket and Martha’s Vineyard. Coastal New Brunswick and Nova Scotia are also under hurricane watches, since winds there could prove slightly stronger. A hurricane watch previously in effect for Down East Maine was discontinued because hurricane-force winds are no longer anticipated as a threat, but tropical-storm-force winds remain likely.
“Lee is expected to be a large and dangerous storm when it reaches eastern New England and Atlantic Canada,” the National Hurricane Center wrote Friday.
While Lee’s track should remain offshore of southern New England, Lee will be a large storm with a very wide footprint. That will be exacerbated by its ongoing “extratropical transition,” or metamorphosis into a nontropical storm. Already, tropical-storm-force winds extend outward up to 320 miles from Lee’s center.
Even as Lee passed 210 miles west of Bermuda on Thursday, it pelted the island nation with frequent 50 mph gusts.
Tropical-storm-force winds could reach easternmost New England as early as late Friday afternoon, with the worst storm effects expected Friday night into Saturday. Rain and wind should ease starting Saturday afternoon in southern New England and Saturday night in Maine.
Most of the coastal Northeast will face 40 to 50 mph gusts. Those occur routinely in the wintertime and may seem easy to write off. However, trees remain fully leafed, meaning they will more effectively “catch” the strong winds. “These conditions are likely to lead to downed trees and potential power outages,” the Hurricane Center wrote.
Moreover, New England has seen repeated rounds of considerable flooding this summer, and the region as a whole is running 10 inches or more above normal for rainfall over the past three months. The saturated soil also makes it easier for trees to fall and increases the chance for flooding.
As of late Friday morning, Lee was 395 miles south-southeast of Nantucket. Maximum winds were 80 mph and were expected to hold steady for the next 12 to 24 hours.
Lee was moving north at 18 mph, accelerating as it began to feel stronger high-altitude steering currents.
Lee was moving north at 16 mph, accelerating as it began to feel stronger high-altitude steering currents.
On infrared satellite, Lee was a shell of its former self. It had a haggard, lopsided appearance, with all the “convection,” or thunderstorm activity, completely eroded from its south side by dry air. The strongest winds were found only north of the decaying system’s center.
That asymmetric form marked the initial stages of “extratropical transition,” during which a fully tropical storm outruns warm, life-giving ocean waters and instead begins to derive energy from mid-latitude temperature contrasts and the overhead jet stream.
In the coming 24 hours, the proximate jet stream will help expand Lee’s wind field even more; though maximum winds will decrease, the storm will be spreading its wind energy over a broader area.
Lee will also acquire the shape of a nor’easter, because of an influx of dry air on its back side punching into its circulation and sculpting it into a comma.
The bulk of any potentially disruptive impacts will be relegated to within a county or two of the coastline in the U.S. Northeast.
-Strong winds: Winds gusting 40 to 50 mph will occur late Friday night and on Saturday across coastal stretches of New England, though Cape Cod may see 50 to 60 mph gusts and a few gusts approaching 65 mph on the Outer Cape. Down East Maine could also see a few gusts to 60 to 70 mph. Lee’s center is expected to come ashore near the southwestern tip of Nova Scotia, where gusts to 75 mph or so can’t be ruled out. Wind gusts of 50 to 60 mph will occur in southern New Brunswick and the rest of the Nova Scotia shoreline.
-Surge: For the most part, the north-northwest winds feeding into Lee’s counterclockwise circulation will be an offshore wind for New England. That will limit surge impacts. A 1-to-2-foot rise in water levels is possible in Long Island Sound, with a general 2-to-3-foot surge not out of the question for the remainder of New England, with north-facing shores most vulnerable. East of the storm’s center in Nova Scotia, winds will be onshore, translating to a 2-to-4-foot surge.
-Heavy rainfall: South of Massachusetts, most of the rain will stay offshore. Outer Cape Cod could see an inch or more, assuming Lee’s precipitation shield backs far enough westward, but places west of a line from Boston to Providence might not see more than a few drops. More meaningful rainfall, on the order of 1 to 4 inches, is forecast for northeastern Maine, New Brunswick and southern Nova Scotia. “This may produce localized urban and small stream flooding,” the Hurricane Center wrote.
-Rip currents will be a hazard for much of the Northeast, Mid-Atlantic and Maritime Canada. Near-shore waves of 10 to 15 feet will be common. Rip currents and rough surf will make venturing into the waters extremely dangerous. Far offshore, waves of 40 to 70 feet are possible.