Major nor'easter clobbering Eastern Seaboard with heavy rain and wind

Flash flood watches and warnings were in place on Tuesday as a major storm system continued to crawl up the Atlantic coast where it was unleashing drenching rain along the Interstate 95 corridor and pounding coastal areas with rough surf and high winds. AccuWeather forecasters say it's just the first of multiple storms that will take aim at the Northeast during the final week of October.

Severe flash flooding was ongoing Tuesday morning in parts of New Jersey as the storm, the first nor'easter of the season, continued to strengthen.

The storm has been categorized as a nor'easter since it is spreading northeasterly winds along the coast and is the first such storm of the season to impact the region. The storm is forecast to complete a counterclockwise loop near the Northeast coast into Wednesday night, which will prolong adverse conditions in New England and Long Island, New York.

Forecasters said the storm had undergone a period of rapid intensification overnight Monday, and before Tuesday evening had officially met the benchmark for bombogenesis, which is when the central pressure of a storm drops by 0.71 of an inch of mercury (24 millibars) or more over a 24-hour period to become what is known as a bomb cyclone. Two similar storms developed in the northern Pacific and slammed into the western U.S. late last week and over the weekend.

The rainfall that pushed into New York City late Monday evening is expected to taper off Wednesday afternoon. The National Weather Service had issued a flash flood watch for New York City to account for the impacts by the heaviest rounds of rainfall. The New York City Emergency Management also issued a travel advisory for Monday evening through Tuesday afternoon.

"We know how quickly these storms can escalate, so everyone, especially those living in basement apartments, should plan accordingly," New York City Mayor Bill de Blasio warned over Twitter on Monday.

The heaviest and steadiest rain had subsided for the New York City area as of midday Tuesday. However, forecasters warned that additional downpours through Wednesday morning, along with runoff from earlier rainfall, could result in flooding in poor drainage areas. Significant rises were anticipated on area streams and secondary rivers in the New York City area and minor to moderate flooding was expected in unprotected locations.

New York Gov. Kathy Hochul declared a state of emergency for the Capital Region, Long Island, New York City, Mid-Hudson and Southern Tier regions late Monday evening. Likewise, New Jersey Gov. Phil Murphy also declared a state of emergency in preparation for the storm's impacts and urged residents to stay off the roads, stay vigilant and follow safety protocols.

Heavy rain that arrived across the New York City area Monday evening will continue to push into central and southern New England into Wednesday, and forecasters say will taper off by the afternoon. The intense rainfall could result in flooding issues in low-lying and poor drainage areas. The heaviest rain is forecast to diminish in intensity throughout the Northeast by Wednesday morning, but some light rainfall could persist throughout the day near the coasts.

AccuWeather forecasters say one added concern with the storm besides its strong winds and drenching rain is that it will target areas that were slammed by Tropical Storm Henri and Tropical Rainstorm Ida during the summer. Impacts from the storm in southern New England will be similar to what Henri caused in late August when travel delays and power outages were widespread.

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The heaviest rainfall amounts are expected in northern New Jersey, northeastern Pennsylvania, southeastern New York state and southwestern Connecticut, where a widespread 4-8 inches can be reached for some through Wednesday.

Locations such as Ridge, New York, and Oak Ridge Reservoir, New Jersey, recorded 24-hour rainfall amounts upwards of 5 inches by late Tuesday night. Even higher, Waldwick, New Jersey, reported a whopping 6.55 inches in the same time frame.

Areas that experience particularly intense and long-lasting rainfall will pick up totals near the high end of this range, with an AccuWeather Local StormMax™ of 10 inches (250 mm) from Monday night to Wednesday.

Elsewhere, rainfall totals of 2-4 inches are forecast from far southern Maine through eastern New York and a large portion of New Jersey. Localized flooding cannot be ruled out, but flooding incidents will be less widespread. Lingering travel delays could still become a problem where water ponds on roadways.

From Nova Scotia westward into the Adirondacks and south into eastern Pennsylvania, Maryland, Delaware and eastern Virginia, 1-2 inches (25-50 mm) of rain are anticipated. Flooding will not be a substantial concern in this area. While some roadways may have standing water during periods of heaviest rainfall, impacts in this area will remain minor.

Defining features of a nor'easter can include howling winds that could be damaging at times. There will be no exception with this storm as winds are expected to gust up to the southern shore of Nova Scotia in Atlantic Canada through Wednesday. The most intense winds were confined to eastern Long Island and the Cape Cod area up northward to coastal New Hampshire on Tuesday night. Cities such as Provincetown, Plymouth and Boston, Massachusetts, were in the zone of greatest risk to see wind gusts from 60 to the AccuWeather Local StormMax™ of 90 mph late Tuesday night.

"Given the long-duration of expected gusty winds above 40 mph and the fact that many trees are still mostly fully-leafed, we are concerned about the risk for significant power outages," AccuWeather Vice President of Forecasting Jonathan Porter said. "This risk is most substantial across Eastern Massachusetts, Rhode Island and Eastern Connecticut as well as Eastern Long Island," he added, noting that power outages could top what was seen with Tropical Storm Henri back in August.

As the storm lingers off the New England coast, blustery onshore winds will remain through Wednesday and result in continued coastal flooding, beach erosion and power outages.

Wednesday morning, over 325,000 residents in Massachusetts were without power, according to PowerOutage.us. With the majority of the outages coming from Plymouth and Barnstable counties, south of Boston, and the total outages are expected to rise even higher. At one point early Wednesday morning in Maine over 25,000 residents were without power. In addition, Rhode Island's outages rose to over 30,000 by Wednesday morning.

Blustery conditions that accompanied this storm, along with the combination of clouds and rain, produced AccuWeather RealFeel® Temperatures 5-10 degrees lower than the actual temperature on Tuesday.

And there's even a chance that the storm could pick up some tropical properties as it heads out to sea.

AccuWeather Director of Forecasting Dan DePodwin said the storm could end up taking on tropical or subtropical characteristics by midweek. If that happens, the National Hurricane Center would give it the name Wanda, the final name in the Atlantic hurricane season's primary list of names.

"It would also be the first named stormed in nearly a month, which is unusual for October when there is typically a secondary peak of hurricane season," DePodwin added.

On top of that, AccuWeather meteorologists say the developing weather pattern will have staying power.

By Thursday, the nor'easter will move away from the eastern United States, and much of the Northeast will be able to dry out. Meanwhile, another storm is expected to approach the region from the west.

"The same massive storm that is currently bringing heavy rain, snow and strong winds to the Western states is expected to slowly move eastward across the country this week," AccuWeather Senior Meteorologist Brett Anderson explained.

The second storm also has the potential to become a nor'easter late this week and this weekend. It is unusual for multiple nor'easters to take aim at the region during this time of the year, according to DePodwin.

That storm may bring another round of significant rain and strong coastal winds to the Northeast just in time for the Halloween weekend, potentially throwing a wrench in the plans of trick-or-treaters.

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