WASHINGTON, May 28 (UPI) -- A tropical depression in the Atlantic has been upgraded to Tropical Storm Bonnie, which is forecast to make landfall in South Carolina Saturday night or early Sunday, forecasters said.
Bonnie could strengthen slightly overnight as it passes over warmer coastal water. The storm was moving northwest at 10 mph as of 5 p.m. Saturday.
It could pack sustained winds of 40 mph, with gusts higher than that and will drench the coastal Carolinas in up to 5 inches of rain during the Memorial Day weekend, according to a weather alert from the National Oceanic and Atmospheric Administration.
Storm surge during Sunday night's high tide is expected to be an additional 1 to 2 feet.
A tropical storm warning is in effect for the Atlantic coast from the Savannah River north to Little River Inlet. Bonnie brings the likelihood of scattered tornadoes over the immediate coastal regions and will cause life-threatening surfs and rip currents through the weekend.
The early-season storm is the first tropical storm to make landfall in 2016 and does so before the official start of the Atlantic hurricane season on Wednesday.
The Carolinas were not the only place under threat of severe weather.
On Friday, two people were killed and four are missing after rain and heavy flooding hit southeast Texas.
"Areas along the Missouri River and its tributaries in west-central Missouri are of particular concern because more rain could cause some levees to overtop," Nixon said in a statement issued Friday evening.
The state has been battered with high winds, heavy rains and flash flooding -- with more rain predicted.
"State emergency management personnel will continue to work with local officials and law enforcement to assess and closely monitor the risk to the levees, and take appropriate action if needed," Nixon said.
More than 12 million people in the Plains were under flash-flood watches and 1.4 million were under flash-flood warnings, NBC News reported. Tornadoes were reported in Kansas and Texas.
The city of Rosenberg, Texas, which is 35 miles southwest of Houston, issued mandatory evacuation orders beginning at 2 p.m. Sunday due to the swelling Brazos River. In Weatherford, Texas, a 10-year-old boy is thought to have been swept up by the Brazos River and is now missing. Parker County Sheriff Larry Fowler said his department is conducting a search for the missing child.
The two fatalities occurred in Brenham, Texas, about 70 miles northwest of Houston. One person was found dead in a mobile home, possibly from drowning, and another was swept away in a car thought to have died of a heart attack, police spokeswomen Angel Hahn said Friday.
Another person is also missing in Washington County's Brenham after encountering high waters. The man was identified as 21-year-old Darren Mitchell, CBS affiliate KHOU reported. Mitchell called his sister Thursday evening to tell her he was trapped in high water, KHOU reported.
Also, two are missing in Travis County, said Travis County Emergency Management spokeswoman Lisa Block. Austin, the state capital, is in Travis County.
The area received more than 16 inches of rain Friday.
Several dozen people were rescued from cars and homes.
"We've probably had well over 100 rescues of people from cars," said Darren Hess, deputy emergency management coordinator for Montgomery County.
Bistro County Judge Paul Pape said more than 100 homes flooded there, forcing at least 50 families into shelters.
This is the fifth disaster declaration issued by Pape since Memorial Day weekend last year.
The declaration allows Pape to ask state agencies for resources. The county is also eligible for federal aid if Texas Gov. Greg Abbott declares the county a disaster area.
Mandatory evacuations were ordered for communities along the Colorado River.
The rain is pushing rivers and creeks in the area toward historic crests.
Last month the Houston area experienced its wettest April with almost 14 inches of rain. The storm killed at least eight people in Texas and flooded 1,000 homes. The previous record was almost 11 inches in April 1976.