NEW ORLEANS—High winds and heavy rains buffeted coastal Louisiana and Mississippi on Friday as a disorganized and unpredictable tropical weather system churned through the Gulf of Mexico, forcing cancellation of Juneteenth celebrations in Mississippi and Alabama and threatening Father’s Day tourism. The system, moving north toward Louisiana through the Gulf of Mexico carried tropical storm-force sustained winds of 45 mph but forecasters said it couldn’t be classified as a tropical storm because it lacked a single, well-defined center. “This one is just a sloppy mess. There’s multiple circulations within this broad area of circulation,” said Benjamin Schott, meteorologist in charge at the National Weather Service office in Slidell, Louisiana. Forecasters said the storm was likely to dump anywhere from 4 inches to 8 inches of rain along parts of the Gulf Coast—even 12 inches in isolated areas. In Louisiana, the threat came a month after spring storms and flooding that …