The first real threat of a tropical storm near Charleston doesn't seem to be developing. But forecasters are expecting "off-and-on" showers and thundershowers through Sunday.

The chance of rain is 50 percent for the weekend. Showers will begin to come in along the coast this morning and spread inland through the day, said meteorologist Bob Bright, with the National Weather service, Charleston. Temperatures will be about 90 degrees all three days.

The National Hurricane Center on Thursday was watching a storm off Apalachicola, Fla., that stretched all the way down to the Yucatan peninsula in Mexico. That system was forecast to come ashore and move through the Southeast over the next two days. But hurricane forecasters gave it only a 20 percent chance of becoming a tropical cyclone.

Computer models did not predict gale-force winds even at landfall and the forecast for Lowcountry rainfall was modest. But with the region teetering on drought conditions, every drop helps.

"It's a lot of moisture, but the chance of it developing is very small," Bright said. "We need the rain."

Reach Bo Petersen at 937-5744 or follow him on Twitter at @bopete.