Tropical Storm Debby (2012)

Tropical Storm Debby was a tropical cyclone that caused extensive flooding in North Florida and Central Florida during late June 2012. The fourth tropical cyclone and named storm of the 2012 Atlantic hurricane season, Debby developed from a trough of low pressure in the central Gulf of Mexico on June 23. The formation of Debby marked the earliest formation on record of the fourth named storm within the Atlantic basin until this record was beaten by Tropical Storm Danielle in 2016. Despite a projected track toward landfall in Louisiana or Texas, the storm headed the opposite direction, moving slowly north-northeast and northeastward. The storm slowly strengthened, and at 1800 UTC on June 25, attained its peak intensity with maximum sustained winds of 65 mph (100 km/h). Dry air, westerly wind shear, and upwelling of cold waters prevented further intensification over the next 24 hours. Instead, Debby weakened, and by late on June 26, it was a minimal tropical storm. At 2100 UTC, the storm made landfall near Steinhatchee, Florida with winds of 40 mph (65 km/h). Once inland, the system continued to weaken while crossing Florida, and dissipated shortly after emerging into the Atlantic on June 27.

The storm dropped immense amounts of precipitation near its path. Rainfall peaked at in Curtis Mill, Florida, located in southwestern Wakulla County. The Sopchoppy River, which reached its record height, flooded at least 400 structures in Wakulla County. Additionally, the Suwannee River reached its highest level since Hurricane Dora in 1964. Further south in Pasco County, the Anclote River and Pithlachascotee River overflowed, flooding communities with "head deep" water and causing damage to 106 homes. An additional 587 homes were inundated after the Black Creek overflowed in Clay County. Several roads and highways in North Florida were left impassable, including Interstate 10 and U.S. Route 90. U.S. Routes 19 and 98 were also inundated by coastal flooding. In Central and South Florida, damage was primarily caused by tornadoes, one of which caused a fatality. Overall, Debby caused at least $250 million in losses and 10 deaths, 8 in Florida and 1 each in Alabama and South Carolina.

Meteorological history

During mid-June, the Intertropical Convergence Zone (ITCZ) made its annual migration northward into the southern Gulf of Mexico. Coinciding with a Madden–Julian oscillation, a weak surface low pressure area developed on June 19, and subsequently moved inland over the Yucatán Peninsula. While the system crossed the peninsula, a tropical wave moved through the northwestern Caribbean Sea on June 18. The wave reached the Gulf of Mexico on June 20 and merged with the low a few days later, spawning a trough of low pressure on June 22. Located in the southeastern Gulf of Mexico, moderate vertical wind shear caused the system to remain disorganized. Nonetheless, Air Force Reserve Hurricane Hunter aircraft indicated that the trough acquired a low-level circulation on June 23, while ships in the area reported tropical storm force winds. Thus, it is estimated that Tropical Storm Debby developed at 1200 UTC on June 23, centered about south of mouth of the Mississippi River.

Becoming a tropical storm on June 23, Debby became the earliest fourth named storm in the Atlantic basin, surpassing the old record set by Hurricane Dennis on July 5, 2005, however with 2016's Danielle the record was beaten by three days. Initially, Debby was predicted to curve westward and potentially threaten Texas. A deepening trough would curve the storm westward, while wind shear was predicted to decrease. Although the storm generated very cold cloud tops, much of the convection was located more than from the center and still displaced to the east. By 1200 UTC on June 24, the forecast path was shifted from east-central Texas to southeastern Louisiana. Despite persistent wind shear, Debby was strengthening and around that time, the storm attained its maximum sustained wind speed of 65 mph (100 km/h). Later on June 24, the National Hurricane Center noted in its next advisory that this "is a very difficult and highly uncertain forecast", citing Debby's slow movement and widespread computer forecast models.

The forecast track for Debby was shifted significantly to the east late on June 24, and it was predicted that the storm would move northward and make landfall near Panama City, Florida. Based on a dropsonde estimate, Debby attained its minimum barometric pressure of at 0000 UTC on June 25. However, the storm began to weaken due to increasing wind shear, drier air, and upwelling of cold water, caused by Debby's slow movement. It was initially composed of multiple small swirls, but consolidated into one well-defined low-level circulation by early on June 25. Due to its excessively slow movement and no prediction for acceleration, the National Hurricane Center remarked that, "the cyclone does not seem to be going anywhere anytime soon." A burst in deep convection occurred later on June 25, though adverse environmental conditions prevented re-intensification. Debby began curving east-northeastward and began to speed up on June 26, in response to a mid-latitude trough digging into the western Atlantic Ocean. While approaching the Florida Big Bend, Debby produced only a small area of deep convection on satellite imagery.

At 2100 UTC June 26, Debby made landfall near Steinhatchee, Florida with winds of 40 mph (65 km/h). The storm weakened quickly after moving inland, and by early on June 27, it was downgraded to a tropical depression, while located about north of Gainesville, Florida. Debby maintained tropical cyclone status while crossing Florida, but degenerated into a trough of low pressure by 1800 UTC on June 27. In the final advisory issued by the National Hurricane Center three hours later, the agency noted that Debby could eventually reacquire tropical characteristics. After its dissipation, however, the remnants did not regenerate into a tropical cyclone, but re-developed a new center of circulation and strengthened slightly due to baroclinic conditions. As it accelerated northward, Debby's remnants became increasingly frontal in nature, and once again degenerated into an open trough at 1800 UTC on June 30; at this time, the disturbance was located south of Newfoundland.

Preparations

Upon development of Debby on June 23, a tropical storm warning was issued from the mouth of the Pearl River to Morgan City, Louisiana, excluding New Orleans

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