The National Weather Service in New Orleans has issued a severe thunderstorm warning for Hancock and Harrison counties, and reports of hail were confirmed in Pass Christian, Long Beach and Gulfport.
The warning will remain in effect until 8:45 p.m.
A previous tornado warning expired at 6:30 p.m. At 5:42 p.m., a severe thunderstorm capable of producing a tornado was near Picayune and moving northeast at 45 mph.
Parts of Gulfport affected by the hail included Community Road near U.S. 49 and John Clark Road south of Mississippi 53, Harrison County Emergency Management Director Rupert Lacy said.
Lacy said the Harrison County safe room will stay open until the storm has passed. The safe room is at 15038 County Farm Road in Gulfport.
Shelters are also open at the Agricola Community Center and Benndale Community Center in George County.
The NWS said there is a 90 percent chance of rain today with severe thunderstorms possible during the watch.
"A tornado watch means that the conditions are favorable for a tornado, but one has not been spotted," said Andrew Ansorge of the NWS. "This is when you need to be thinking about what to do if a tornado warning is issued. A tornado warning means that a tornado has been spotted."
Ansorge said the most severe weather could happen between 3 and 10 p.m.
A wind advisory has also been issued until 6 a.m. Wednesday. Ansorge said this could be dangerous outside of the storm front.
"We have a very strong low pressure moving through the Mississippi Coast," he said. "This could bring winds with gusts up to 60 mph outside of the storm and the winds will likely be around until sometime Wednesday morning.
"The Coast Guard has alerted mariners to secure their vessels, including personal watercraft, beached kayaks, canoes, life jackets, pool floats and other equipment that high winds could turn into debris. Winds are likely to increase to small-craft advisory levels by Tuesday afternoon, with gusts to gale-force winds expected through early Wednesday."
Coast Guard Sector Mobile will broadcast safety information for recreational and commercial mariners via VHF FM marine radio.
Several schools dismissed classes early today and some local government offices closed early in front of the severe weather threat.