Early Tuesday, the Weather Prediction Center said the storm could be historic, but Rich Otto, lead forecaster at the National Weather Service's Weather Prediction Center outside of Washington, said that may have been going a bit too far.
"Things will change; that's a guarantee," Otto said. "Nothing ever stays the same with these forecasts."
Otto said an upper-level disturbance in the air is moving from the Pacific to the Rockies to the southern plains. It should pass over Texas, hit the Ohio Valley, join with other unstable air and become a nor'easter Friday evening over the Mid Atlantic, moving up the coast on Saturday.
"Since the storm is arriving on a southern track, impacts will include Kentucky, Cincinnati, West Virginia, Northern Virginia into D.C., then Philly," said meteorologist Ryan Maue of the private WeatherBell Analytics.
Then once it gets up north, expect strong winds — gusting easily to 50 to 60 mph — beach erosion, and storm surge in the New Jersey area, Maue said.
—CNBC's Everett Rosenfeld contributed to this report.