A flow of tropical moisture ahead of a slow-moving front will trigger heavy rain and raise the risk of flash and urban flooding problems along the Atlantic Seaboard late in the week.
While spotty showers and storms Tuesday and Wednesday are forecast to occur ahead of the heavier rainfall, there will be a greater risk for disruptions to outdoor activities and travel problems on Thursday and Friday in the mid-Atlantic and on Friday and Saturday in New England.
After a wedge of cool air trims temperatures in much of the Northeast at midweek, a front with showers and thunderstorms will push toward the East Coast late in the week.
Tropical moisture, which has produced flooding and mudslides in the Virgin Islands and Puerto Rico since last week, will be drawn northward along the Atlantic coast around the same time the front arrives from the west. While the system is not expected to develop, it is carrying tropical moisture.
The front alone has the potential to bring a general 1 to 2 inches of rain from showers and thunderstorms. However, where the tropical moisture gets involved, double that amount can fall in localized areas from Georgia to Maine.
As long as the narrow corridor of heavy rainfall continues to move along, widespread flooding problems will be avoided. If the zone of heavy rain were to stall, there is more of a risk for stream and river flooding, along with widespread urban flooding issues.
There will be minor incidents of flash and urban flooding, with poor visibility over a several-hour period as the band of heavy rain pivots slowly to the northeast later this week.
Major cities that will be impact by a period of drenching showers and thunderstorms with the associated travel delays include Atlanta, Charlotte, Washington, D.C., Baltimore, Pittsburgh, Philadelphia, New York City and Boston.
In the wake of the drenching rain, cooler air will roll eastward from the Midwest in time for the weekend. Similar to a storm that brought cool and unsettled conditions to the area a week ago, this new storm the upper atmosphere has the potential to bring angry clouds and spotty showers mainly during the afternoon and evening hours.
Beneath the storm in the upper atmosphere, high temperatures may be held to the 50 over the mountains and the lower 70s in many areas east of the Appalachians.