Alex Sosnowski, Senior Meteorologist for AccuWeather.com
AccuWeather Global Weather Center — May 18, 2018 — AccuWeather reports a plume of tropical moisture will raise the risk of flooding from the Carolinas to upstate New York, while downpours soak parts of the Midwest and rain spreads into New England this weekend.
Downpours may develop, cluster and bring flooding to some counties in the East and barely dampen others.
Portions of the eastern Great Lakes and central and northern New England that have been spared rain for a time this past week will join in with the wet weather as the moisture spreads northward through Saturday.
There will be some gaps in the rainfall. The best bet for people with outdoor plans and projects is to monitor the radar on their mobile devices as the weather may be vastly different from the start of the day to the midday, afternoon and evening with few exceptions.
The most common problem created by the downpours will be street and highway flooding.
“Within the swath of moisture from Florida to New York state, someone is going to get clobbered with very heavy rainfall and flooding problems,” according to AccuWeather Senior Meteorologist Bernie Rayno.
However, some small streams in the mid-Atlantic region will spill out of their banks. Motorists should never drive through flooded roads. Property owners along small streams should monitor water levels and take action as needed.
The combination of prior rain from this past week and additional rain through Saturday will cause moderate flooding along the Potomac River, as well as portions of the Rappahannock in Virginia and the Millstone in New Jersey.
Most other major rivers in the region, such as the Susquehanna, Delaware and Ohio, should be able to handle the rainfall with little or no problems.
Sporadic airline delays are likely due to patchy early morning fog, an occasional low cloud ceiling and localized downpours.
Slow-moving, torrential downpours focused on an area from southern Virginia to the Delmarva Peninsula early Friday morning. From 1-3 inches of rain fell in as many hours in some locations.
This particular batch of rain is forecast to break down while crawling northward into Friday afternoon.
However, new clusters of heavy rainfall are likely to develop along the southern and mid-Atlantic coasts through Saturday.
During Saturday, it may not rain much of the day from part of south-central Pennsylvania to the Piedmont areas of Virginia and the Carolinas.
Some of the downpours in the Northeastern states in general will be accompanied by some thunder and lightning.
A small number of locations mainly south and west of New England and New York state may be hit by a gusty thunderstorm during the afternoon and evening hours on Saturday.
Drying trend may sputter at times
On Sunday, much of the rain is likely to exit the Atlantic coast with only very spotty showers in its wake.
A pocket of showers and thunderstorms may push eastward from Illinois, Wisconsin and Indiana to Ohio and the Lower Peninsula of Michigan.
During next week, just about every area east of the Mississippi River is likely to have at least a couple of days where it rains for a few hours.
However, longer stretches of dry weather are likely from the Great Lakes to the Northeast, especially during the middle and latter part of next week.