This would be a bad end to the week for millions with heavy rain and winds stretching from the Ohio Valley and the mid-Atlantic to the Northeast and eventually New England.
The biggest impact may not be heavy rainfall like the last few storms, but rather the threat of coastal flooding, which in some places may witness the most significant tidal flood event since Hurricane Isabel in 2003.
On Friday morning, 18 million people were under coastal flood alerts, where waters can be up to 3 feet high especially at times of high tide. Meanwhile, 21 million people were under wind alerts across the mid-Atlantic to the northeast where winds could reach 50 mph especially along the coast and 10 million people were under flood watch where up to 2 to 4 could fall. inches of rain on saturated ground.
Over the course of Friday, rain will be heavy at times, resulting in puddles on the roads and isolated flooding, especially in cities.
However, the greatest flood risk will come from coastal flooding. Strong inshore winds combined with rising residual water levels from Norrester earlier in the week could cause this to happen One of the largest tidal floods in the past 10-20 yearsand the worst since Isabel in 2003.
The potential impacts of coastal flooding would be impassable roads and water to homes, low coastal buildings and flooded marinas. This threat will continue through the high tide cycles on Saturday afternoon.
Of particular concern are the areas along the Chesapeake Bay, Delaware Bay, Delaware River, and Potomac River where dozens of river gauges along those waterways are expected to reach moderate to significant flood stage.
One of those areas, Delaware Bay at Reddy Point, was expected to break the highest water level ever recorded in Delaware Bay. According to a meteorologist, Bill Karens, if the forecast comes to fruition, it will be higher than Hurricane Sandy nine years ago today and higher than the historic Norwegian cyclone in April 2011.
Parts of the Washington, Baltimore, and Philadelphia metro areas may experience tidal flooding. Annapolis, Maryland, was already hit by flooding Friday morning.
By Saturday, heavy rain is expected in northern New England, but rain and gale-force winds will continue across the mid-Atlantic and Northeast into Saturday night.
District-wide precipitation will fall 1 to 3 inches through Saturday night, with higher amounts locally reaching 4 inches.
The good news is that the storm system will come off the coast in time to provide dry skies for trick-or-treaters.