Incoming storms could bring up to 6 inches of rain. A flash flood watch is in effect.

Horry and Georgetown counties are under a flash flood watch from midnight Sunday until 8 a.m. Tuesday from an incoming low-pressure system that could spawn river flooding later in the week, according to the National Weather Service in Wilmington, N.C.

The watch was issued for all of northeast South Carolina and southeast North Carolina through Tuesday morning as a low-pressure system moves in bringing the risk of heavy rainfall.

A forecast prepared at 4:30 p.m. Sunday showed a high risk for flooding through Tuesday morning with rainfall amounts totaling 3 to 6 inches across the region. Isolated higher amounts are possible in some areas, according to the NWS.

“River flooding could become an issue later in the week,” according to an update from Stephen Keebler, a forecaster with the NWS. “The heaviest rain is expected to fall late Monday into Tuesday morning.”

Widespread flooding of roads and streams could become an issue later Monday into Tuesday morning, Keebler said.

“Most of the area rivers are now forecast to go into minor flood stage approaching moderate flood stage,” he said.

Grounds are expected to become saturated as periods of heavy rainfall move across the area, according to the flash flood watch alert from the NWS. “This has the potential to lead to flash flooding, especially in locations with poor drainage such as urban areas or in and around culverts. Excessive roadway ponding is also likely and at times some roads may become impassable, especially if drainage ditches overflow onto roadways.”

A small watercraft advisory is in effect until Tuesday morning.

A flash flood watch means that you should be on the lookout for flooding that may develop quickly.

The National Weather Service warns that flash flooding poses a “very dangerous situation.”

“You should monitor later forecasts and be prepared to take action should flash flood warnings be issued,” according to the NWS.

Emily Weaver: 843-444-1722, @TSNEmily