An area of low pressure moving into the northeast will produce widespread heavy rains which could cause some flooding conditions; on the northern side of the storm, accumulating freezing rain and ice is also expected.
On Sunday, an area of low pressure over the Central Plains and Midwest will intensify. Ahead of that system, a strengthening upper level ridge will lift along the East Coast. A warm front will lift along the coast late in the day, and overrunning precipitation will develop out ahead of the warm front late in the day Sunday. By Sunday night and early Monday, the precipitation will become more widespread. With milder air surging up the coast, most precipitation will fall as plain rain. But in northern Pennsylvania, extreme northern New Jersey, and points north, the rain could start as freezing rain or sleet, leading to an icy accumulation. Snow could even mix in at times there, but most accumulating snow will be confined to the higher elevations of New England from this primarily rain event.
On Monday, an upper level low will move into the Great Lakes with a weak surface low pressure system expected to form over southern New Jersey. Rain will continue for much of the northern Mid Atlantic and southern New England throughout the day Monday as the low sits over the region. On Tuesday, low pressure over the Great Lakes will move into eastern Canada and will drag a cold front through the region during the late afternoon and evening hours. With colder air moving in behind the system, conditions will begin to dry out. While some lake effect snow showers and isolated snow squalls will be possible on Wednesday, high pressure should dry out most areas.
Before the rain clears out, though, the National Weather Service is concerned about flood threats in the northeast from the rain. Northern New Jersey is especially susceptible due to the recent wet weather there. The National Weather Service will issue specific flood-related advisories for communities as flood conditions threaten them.