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Tropical Storm Fay forms, set to bring heavy rainfall to Mid-Atlantic coast, Northeast

It’s the earliest sixth-named storm on record

A satellite shot of Fay on Thursday afternoon. (RAMMB/CIRA)

The record-setting start to the 2020 Atlantic hurricane season became even more remarkable on Thursday afternoon, when Tropical Storm Fay formed east of North Carolina. Fay is the earliest sixth-named storm in recorded history.

Fay is set to ride up the East Coast, bringing heavy and potentially flooding rains, with a secondary risk of rough surf and sporadic gusty winds.

Tropical storm watches were hoisted for much of coastal New Jersey and New York, including Long Island.

All of Massachusetts, Connecticut, Rhode Island, New Jersey, and Delaware, along with much of southeastern New York, including New York City, and the Delmarva Peninsula were placed under a flash flood watch where Fay could dump torrential rainfall.

The year’s sixth Atlantic named storm comes roughly two months ahead of schedule; typically, a season doesn’t see its "F" storm until early September.

Fay formed nonetheless, however, defying all the rules as it quickly organized on Thursday afternoon. NOAA Hurricane Hunters probed the system via aircraft, finding a newly-developed closed circulation surrounded by gusty winds. Tropical storm force winds were found well offshore, with gusts at flight level up to 50 mph to the east and northeast of Fay’s center.

At the surface, maximum sustained winds were estimated at 45 mph. The storm was moving north at 7 mph. Strengthening is likely through landfall late Friday or early Saturday.

On Thursday morning, the system had appeared rather disheveled, but shifted its axis of rotation while reorganizing over the course of the day.

Lukewarm water temperatures several degrees above normal helped support Fay’s genesis, also contributing to the excessively humid environment that will set the stage for heavy rain associated with the system. Up to four to six inches of rain may fall in some areas and the storm could spawn a few tornadoes and waterspouts.

The Atlantic hurricane season is off to a record fast start and is likely to get worse

Fay now

On Thursday morning, the tempestuous neophyte, its spin dubbed “Invest 98L” by the National Hurricane Center, was centered off North Carolina. While a peppering of showers adorned its broad circulation, the greatest moisture and most concentrated downpours wrapped into the system well to its east.

Around noontime on Thursday, it became apparent that the system may be trying to reorganize and shuffle its main axis of rotation. A swirl, or mesoscale convective vortex, appeared on radar induced by thunderstorm activity far northeast of the low-level center.

That second area of emerging rotation likely grew downward toward the surface, becoming the system’s dominant center of circulation. This process could was catalyzed by the thunderstorm activity that first initiated it.

Initially, some of the rotation that helped seed Fay actually stemmed from a thunderstorm complex over Louisiana on July 4.

An uncertain forecast

Despite its likelihood of affecting land on Friday, uncertainty in Fay’s exact path remained enormous even Thursday evening. Computer models struggled simulate Fay’s eventual motion since they were unsure of where its center would organize.

However, computer model simulations will likely converge into a clearer solution late Thursday evening.

What we know is that a trough of low pressure arriving from the Ohio Valley may try to “scoop” the system inland. Meanwhile, the low pressure’s associated cold front could act as a guardrail, steering the system up the East Coast and focusing its heavy rains.

Predicting where that axis of rainfall sets up will be a challenge. Some models drag the heaviest rain as far inland as the Chesapeake Bay, while others — like the Canadian model or the German ICON model — simulated an offshore track that only clips southeast New England.

Most likely scenario

Fay’s heaviest rainfall will probably remain east of the system’s center, but near-record atmospheric moisture could set the stage for torrential downpours with three-inch-per-hour rainfall rates.

It appears unlikely that the western half of the cyclone, which would affect land areas, will adequately “fill in” with rainfall to match the juiciness of the eastern side, so rainfall totals may fall sharply between the ocean and inland areas.

At this point, Fay will probably brush up along or move slightly inland over the eastern Delmarva Peninsula sometime Friday afternoon, continuing northward through New Jersey and very near to the west or over New York City.

If landfall does occur in New York, it would mark the first landfalling tropical system there since Irene in 2011.

The Delmarva Peninsula should expect the bulk of the system’s rainfall late Thursday night into Friday morning, with conditions improving in the afternoon. The heaviest rain is likely at the beaches; locations such as Ocean City, Md., and Bethany Beach and Rehoboth Beach in Delaware could see a quick two or three inches. Amounts may sharply decrease as you head inland over the Delmarva and especially west of the Chesapeake Bay. While some showers are possible in Washington and Baltimore early Friday, areas along and west of Interstate 95 may miss out on the rain altogether.

Over most of the New Jersey, New York City and the Hudson Valley, up to two to four inches of rain could fall while Philadelphia would probably be fringed. The most intense rainfall would come Friday into early Saturday.

In areas that see the heaviest rain, a few five- or six-inch amounts can’t be ruled out.

Subtle shifts make a world of difference

Even the most reliable weather models have been remarkably inconsistent in their depictions of what may unfold, “windshield wipering” with their placement of the heaviest simulated rain totals. As such, a westward shift of 50 or 100 miles — which is feasible — could soak the entirety of the Delmarva Peninsula with several inches of rain and even bring a half inch or more to Washington and Baltimore. That’s less likely, but remains possible.

Meanwhile, a jog to the east — which would have a greater chance of occurring — could shift the heaviest precipitation offshore, sparing New York potential urban flooding issues Friday night and instead leaving the wettest weather to southeast New England.

Surge and wind impacts

The system probably won’t produce much in the way of wind, with 30- to 35-mph wind gusts possible along the immediate coastline from the Chesapeake Bay through Long Island. If the system does intensify into a tropical storm, a few 40-mph gusts would be possible, primarily east of the center — with the greatest risk on Long Island.

Storm surge flooding, the storm-driven rise in water above normally dry land, is not anticipated to be an issue, although dangerous rip currents and heavy surf are likely along the Mid-Atlantic and Northeast coast.

An isolated waterspout can’t be ruled out north and east of the system’s center, with a low chance of a sporadic tornado northeast of the system’s center if the system moves inland.

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