A slow-moving batch of rain and locally gusty thunderstorms will enhance the risk of flash flooding from the Southeast to the mid-Atlantic into Friday night.
The wet weather is from the same system that unleashed severe weather from the southern Plains to the lower Mississippi Valley spanning Wednesday to Thursday, and excessive rainfall in part of the Deep South on Thursday night.
A flash flood emergency was issued for part of southeastern Mississippi, including the city of Hattiesburg, on Thursday night as a persistent line of thunderstorms moved over the city and dumped over 6 inches of rain.
There were numerous reports of homes and businesses taking on water, road closures, river flooding, stalled vehicles and water rescues from southeastern Louisiana to western Alabama.
Multiple vehicles stalled in flood waters along Providence Street. The roadway is closed from 7th to 8th. Drivers avoid the area, and find an alternate route. pic.twitter.com/MIcGv46Iz2— Hattiesburg PD (@HattiesburgPD) December 27, 2018
Into Friday night, the corridor of heaviest rainfall will shift farther east, extending from the Florida Panhandle to part of the mid-Atlantic.
Places such as Tallahassee, Florida; Wilmington, North Carolina; Richmond, Virginia; and Philadelphia will be within the zone of heavy rainfall and enhanced flood risk.
People heading to the airports or hitting the roadways along this corridor should anticipate slower travel and may have to reroute due to flooded streets.
This latest round of rain is expected to cause many rivers in the region to overflow their banks, as water levels remain high from a soggy past few weeks.
Anyone living in low-lying, flood-prone areas or those near swollen streams and rivers should pay close attention to water levels and local advisories.
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"Isolated severe thunderstorms cannot be ruled out in northeastern Florida, Georgia and the Carolinas on Friday," said AccuWeather Senior Meteorologist Alex Sosnowski, adding that the severe weather would not be as widespread as prior days.
Locally damaging winds will be the main threat along this corridor, in addition to the flash flooding.
Given how saturated the ground is already, even a moderate wind gust of 40-50 mph can be enough to topple trees, which can then bring down power lines and leave some communities in the dark.
"At the very least, the potential for flooding downpours and locally strong winds will continue as the storms approach the northeastern Gulf Coast and the southern Atlantic Seaboard Friday night," Sosnowski said.
As the Northeast largely dries out for Saturday and Sunday, patches of rain and drizzle are forecast to linger over the Southern states for the final weekend of 2018.
Even though the heaviest rain will have exited by this time, flooding problems can still remain.
Dozens of rivers from the Interstate 10 to I-40 and I-81 corridors in the South and mid-Atlantic are expected to reach minor to moderate flood stage this weekend, according to National Weather Service hydrologists.
AccuWeather meteorologists are monitoring the potential for additional bouts of rain during New Year's Eve and the first days of 2019 to trigger new and worsening flooding problems across the South.