Even though snowflakes are starting to fall in some places, this year's monstrous hurricane season isn't quite over yet.
There's increasing confidence among weather forecasters that a late-season tropical storm could morph into a scary Halloween-eve rain and windstorm for the northeast United States. The forecast is frightening: The National Weather Service says the storm could be among the strongest ever recorded during the month of October in New England.
From Minnesota to Central America, the dangerous components are coming into place. On Friday afternoon, the National Hurricane Center upgraded a swirling mass of clouds off the northern coast of Honduras to Potential Tropical Cyclone Eighteen—a technical way of saying that a tropical storm is in the late stages of formation and headed toward land.
By Saturday, the NHC expects this system to congeal into Tropical Storm Philippe—pushing this year's hurricane season further into the upper echelon of the busiest of all time. Philippe could bring a quick eight to 10 inches of rain to parts of Cuba, the Bahamas, and South Florida by Sunday, when it will be sucked northward into an advancing Midwest cold front currently generating early-season snowfall over parts of Minnesota, Iowa, and Wisconsin.
Philippe and the cold front will join forces and produce a rapidly intensifying coastal storm on Sunday and Monday that will make a beeline for the New York City area—enough for the National Weather Service to begin issuing wind and flood advisories for nearly all of New England. The storm won't officially be a nor'easter—most of the worst winds will be from the southeast, not the northeast, the defining feature of a nor'easter—but consequences could be worse: By the time it reaches land, the storm could be as strong as or stronger than any other storm ever measured during the month of October in the region. (Superstorm Sandy was much stronger, but it made landfall in New Jersey, not New England.)
The result: a high-speed meteorological conveyor belt of tropical moisture, known as an "atmospheric river," aimed squarely on shore. It's been pretty rainy in New England over the past few days, and, despite an ongoing drought, this storm will bring widespread potential for rapid flood onset. Between three and five inches of rain should fall in just a few hours on Sunday night and Monday morning—enough to rival some of the most intense single-day rainstorms ever measured in the region in late Autumn. Should the storm's center intensify as much as is currently forecast, wind gusts of nearly hurricane force could strike the shores of Long Island and Cape Cod on Monday.
The whole event will have a distinctly tropical feel—not quite as extreme as Hurricane Irene in 2011, but much of the same region will be affected. The Catskills and Adirondacks of New York, almost the entire states of Vermont and New Hampshire, parts of western Maine, and the Berkshires of western Massachusetts could all see flash flooding in the narrow river valleys of the mountains.
Of course, as with all weather events in 2017, part of this storm's ferocity can be traced back to our warming planet. As it zooms past Florida, Philippe will be passing over the exceptionally warm Gulf Stream current, and water temperatures off the East Coast are some of the most unusually warm anywhere on the planet right now. That warm water will boost evaporation rates and enhance the storm's rainmaking potential.
Storms like this fit the mold of what we can expect in the decades to come: the extension of hurricane season later and later into the year with storms of deepening severity. A frightening prospect indeed.