FORT LAUDERDALE, Fla. - Florida's rapidly increasing number of coronavirus cases is turning Miami into the “epicenter of the pandemic,” a top doctor warned Monday, while an epidemiologist called the region's situation “extremely grave.”Those assessments came as Florida recorded more than 12,000 new confirmed coronavirus cases Monday after a record-setting weekend, a spike that partly reflects the larger number of tests being performed but also a high percentage of those returning positive.