Concurrently, a tropical wave approached from the east and merged with the low on June 22 which led to the formation of a trough across the southern Gulf of Mexico.

[9] By 4:44 EDT, weak thunderstorm cells were noted over Collier and Monroe Counties; however, they were not considered as significant as normal tropical cyclone-produced supercells.

[10] Conditions became more conducive for tornadic activity by the late-morning hours of June 24 as Debby's broad circulation meandered generally northeast.

[15] Analysis of surface winds by the SPC at 7:01 p.m. EDT showed a 60 mph (97 km/h) low-level jet and increasing helicity values of 300–500 m2/s2.

[6] In the pre-dawn hours of June 25, a new band of thunderstorms developed over central Florida and a new tornado watch was issued at 4:40 a.m.

[19][20] Poorly modeled dry air entrainment and subsidence ultimately suppressed formation of tornadic storms throughout the day.