Parts of Tropical Storm Cristobal brush South Florida.(Knight Ridder Newspapers)

MIAMI _ Tropical Storm Cristobal, a weak but stubborn system, swiped South Florida with its outlying bands of heavy rain Wednesday, and forecasters warned of dangerous conditions Thursday in offshore waters.

Defying predictions that it would move farther out to sea, the storm lingered in the Atlantic close to Florida, propelled high seas toward the coast and helped fuel squalls that moistened much of the region.

Forecasters cautioned beachgoers to be alert for riptides and boaters to expect hazardous conditions Thursday at ocean inlets. Swells could rise to eight feet, and conditions will be particularly dangerous as the tide ebbs at 8:30 a.m. EDT and 2:30 …