Tampa NWS is saying that these two features (ULL and surface trough) move through and then stall on Friday before moving east again out into the Atlantic.

Hazardous Weather Discussion: THESE FEATURES ARE EXPECTED TO REMAIN IN THE REGION FRIDAY BEFORE MOVING BACK TO THE EAST SATURDAY AGAIN GENERATING SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. SURFACE HIGH PRESSURE SHOULD MOVE BACK OVER THE REGION LATE THIS WEEKEND INTO NEXT WEEK BRINGING A RETURN TO A MORE TYPICAL SUMMERTIME PATTERN WITH SCATTERED MAINLY AFTERNOON AND EVENING SEA BREEZE THUNDERSTORMS EACH DAY. GUSTY WINDS...DEADLY LIGHTNING AND LOCALLY HEAVY RAINS
WILL BE THE MAIN HAZARDS EXPECTED WITH THE STORMS.

NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
553 AM EDT THU JUN 28 2007