The location of the low level ridge axis across south central Florida (Figure 1), as indicated where winds shift from southeast to southwest, put most of the region in a rather light south to southwest flow on Tuesday June 18, 2013.
Figure 1 - Low Level Analysis from 8 AM EDT on June 18, 2013
To the north of the ridge axis the southwest low level winds helped to push the west coast sea breeze inland quickly with a few showers and thunderstorms developing during the early afternoon hours over the coastal counties. As this convection developed and eventually dissipated you could clearly see the outflow boundaries on the Doppler radar, light blue lines propagating away from the rain areas (Figure 2) and on Visible Satellite images as thin lines of clouds spreading out from the storms (Figure 3). These outflow boundaries are similar in effect to a cold front, with passage marked by a wind shift and usually a drop in temperature. New thunderstorms often develop along outflow boundaries, especially near the point of intersection with another boundary. The outflow boundaries on this day formed in impressive almost circular patterns, similar to dropping a rock into a slow moving body of water. They spread out and collided with each other and the sea breeze helping to develop a few more showers and thunderstorms over inland areas as the afternoon and evening progressed.
Figure 2 - NWS Tampa Bay Doppler Radar Base Reflectivity from 1:30 PM to 5:33 PM EDT on June 18, 2013
Figure 3 - Visible Satellite from 1:32 PM to 5:32 PM EDT on June 18, 2013