The chance of a tropical or subtropical cyclone in the eastern Gulf of Mexico over the weekend has increased to 40 percent, threatening to dampen the Memorial Day weekend in South Mississippi.
The Mississippi Coast could receive 3 to 4 inches of rain, according to the National Weather Service.
The National Hurricane Center had forecast a 20-percent chance of a storm for the weekend on Monday and announced the increased probability on Tuesday.
The projected path and the probability of heavy rain indicate the heaviest rains will come late Friday, Harrison County Emergency Management Director Rupert Lacy said.
The five-day projection is based on a surface trough and deep-layer moisture meeting north of San Andres Island to just south of Grand Cayman Island, forecasts show. Subtropical or tropical development is likely late over the next five days as the system moves into the central or eastern Gulf, an NWS alert says.
So what's the difference between a tropical storm and a subtropical storm?
Subtropical storms usually don't become as intense as tropical storms or hurricanes, according to accuweather.com.
Both can bring heavy rain, flooding, damaging winds and rough seas and can cause beach erosion.
However, tropical storms generally are more compact, while subtropical storms typically cover a larger area, accuweather says.
Rain could affect holiday weekend plans and events, including the Conference USA tournament games at Shuckers Stadium in Biloxi. The games start Wednesday and run through Sunday.
The weather forecast through Thursday is partly sunny with a chance of seasonal thunderstorms. Highs will be in the mid- to upper 80s, with overnight lows in the low 70s.
It's unclear whether the weather will improve by Monday.