The National Weather Service reports that a tornado was spotted around 235PM EDT just west of the Miami Airport in southeastern Florida, moving northeast through the suburbs of Miami proper. While the rotation wasn't immediately evident on radar, the storm moving past the airport had a very clear pendant-like feature, which is likely where the tornado was located at the time.
Here's a zoomed-in view of the above radar image, showing the appendage where the tornado was likely located just before it was spotted west of the airport.
There are pictures going around on Twitter of a waterspout reportedly offshore from Miami, and this is not the same storm. This tornado was over land.
Other storms in the area are exhibiting signs of rotation, so anyone who lives in southeastern Florida should be on alert for possible tornadoes this afternoon.
[Images via Gibson Ridge]