With its windswept rains, the storm is likely to become the first nor’easter of the fall. Some of the storm’s heaviest rain could fall in the Mid-Atlantic. Washington and Baltimore could both receive two inches, on top of what has been one of their rainiest years to date.

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The storm is presently in an incipient phase. Rain from Willa’s remnants is spreading over San Antonio and Austin, which are both under flash flood watches. But the flood risk should diminish Wednesday night as the rain moves to the east toward Southeast Texas and Louisiana. At the same time, a low pressure system will develop in the northwest Gulf of Mexico, incorporating that moisture; this will become the East Coast storm.

As this low pressure zone scoots across the northern Gulf of Mexico through Thursday night, moderate to heavy rain will break out across southern Mississippi, Alabama, the Florida Panhandle and southern Georgia, drenching some of the same areas hit by Hurricane Michael just two weeks earlier. Around one to two inches of rain may fall.

By Friday, the low pressure area will turn northeast, heading toward the Outer Banks, dispensing moderate to heavy rain on the Carolinas and Virginia. This is when it will interact with a cold front and take on the characteristics of a nor’easter.

Friday night, a driving rain will sweep over the Mid-Atlantic, drenching Richmond, Washington, Baltimore and Philadelphia. Winds will start to intensify, especially in coastal areas of the Mid-Atlantic. Gusts may hit 20 to 30 mph along the Interstate 95 corridor and 30 to 45 mph along the coast.

On Saturday, rain and wind will gradually ease in the Mid-Atlantic and increase from New York City to Boston.

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By Saturday night, storminess will taper in southern New England while sweeping through Maine. On Sunday, the storm will end except for some showers in interior New England in its wake.

In most places, rain should last about 24 hours. Here’s a rough timeline of when the rain will start and stop in select East Coast cities:

Washington: Rain begins between 1 and 5 p.m. Friday and ends between 11 a.m. and 3 p.m. Saturday.

Philadelphia: Rain begins between 5 and 9 p.m. Friday and ends between 4 and 8 p.m. Saturday.

New York: Rain begins between 1 a.m. and 5 a.m. Saturday and ends between 12 a.m. and 4 a.m. Sunday.

Boston: Rain begins between 6 and 10 a.m. Saturday and ends between 6 a.m. and 10 a.m. Sunday

Rainfall amounts should be pretty uniform between 1 to 1.5 inches along most of the East Coast, but there’s a bull’s-eye around Washington and Baltimore, where around two inches is possible.

Coastal effects

While this storm will dump widespread rain, it is not expected to rapidly intensify and be a huge wind producer. Even so, some gusts could reach 40 to 50 mph in coastal areas from the Delmarva Peninsula through southern New England.

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The storm’s winds will push extra water toward shore, resulting in the possibility of minor to moderate coastal flooding around high tide. “It appears as though the high tide cycle of most concern is the one on Saturday morning,” the National Weather Service office serving the Delaware and New Jersey beaches wrote. “The latest guidance is suggesting widespread minor flooding along the coasts of Delaware and New Jersey and up into Delaware Bay.”

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Snow

There may be enough cold air in the high elevations of New England for some snowfall into Saturday night before mild air pushes northward and changes it to mixed precipitation and rain. “Can`t rule out accumulations of heavy wet snow with strong elevational dependence later Saturday thru Saturday night,” the National Weather Service in Burlington, Vt., wrote.

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