Tropical Storm Isidore (1984)

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale

Map key

Saffir–Simpson scale

  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown

Storm type

Tropical cyclone

Subtropical cyclone

Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

The storm system that would become Isidore originated in a nearly stationary frontal boundary situated near the Bahamas. On September 24, a ship reported winds of about 30 mph (48 km/h) in association with the disturbance. However, satellite imagery indicated that convection was just beginning to organize. Satellite imagery and Air Force reconnaissance reports documented the formation of a tropical depression early on September 25; a special statement was later issued by the National Hurricane Center (NHC) confirming the existence of the depression, and tropical cyclone advisories were initiated at 12 pm EDT.[1] The depression moved west-northwest while tracking through the Bahamas. As it did so, it moved across Cat Island and passed near several others.[1] The cyclone attained tropical storm status on September 26, receiving the name "Isidore".[2]

While located near the northern tip of Andros Island, Isidore reached its peak intensity. The barometric pressure fell to 999 mb, with sustained winds of 60 mph (95 km/h). The storm continued moving northwest, though it failed to strengthen significantly over the Florida Current. The cyclone made landfall near Jupiter, Florida with sustained winds of about 50 mph (80 km/h) and subsequently moved inland. Previously, a large high pressure area over the eastern United States had prevented the cyclone from moving northward. The high moved away, allowing for Isidore to curve to the northeast, emerging over water near Jacksonville, Florida. The storm continued towards the northeast, passing about 80 mi (130 km) off of the Carolina coast. Isidore downgraded to a tropical depression on October 1, and was absorbed in a frontal zone later that day. Isidore was one of many storms during the 1984 season that formed in relatively cool baroclinic environments.[2]

Rainfall from Isidore in the United States

Due to its mild nature, Isidore was described as a "safety test".[3] Gale warnings were issued from as far south as Key West, Florida, to as far north as Virginia, including parts of Georgia, South Carolina, and North Carolina.[4] A private meteorological service stated that Isidore was to intensify to hurricane status, leading to some confusion regarding preparations.[5] Along the Treasure Coast of Florida, citrus farmers burned seedlings potentially infected with canker to prevent heavy rains from spreading the disease.[6] Red Cross volunteers readied a shelter with supplies such as cots and sheets, though it remained unused. In Martin County, hundreds of firefighters were on standby.[7] In Miami, rain from the storm led to the cancellation of horse races at the Calder Race Course. State parks in Monroe County were temporarily closed.[8]

In Indian River, Martin, and St. Lucie counties, students were sent home early, and after-school actives were canceled. The South Beach Jetty Park in Fort Pierce was closed.[7] In southern portions of the state, residents prepared their boats for the storm, and 50 F-4 Phantom fighter jets were evacuated from the Homestead Air Force Base and moved to bases in South Carolina.[9] Lumber yards, groceries stores, and hardware stores reported unusually high demand for emergency supplies, though certain smaller businesses closed early. Gasoline stations in the region "were doing bumper-to-bumper business".[10] Farther to the south, in the Florida Keys, an emergency operations center was opened in response to the storm.[11]

In Nassau, Bahamas, Isidore produced flooding rains and gales.[12] There, the storm forced the closure of schools and banks.[13] Heavy precipitation fell throughout the island chain, but no serious damage was reported.[14]

Winds from Isidore gusted to 73 mph (117 km/h) in the St. Augustine, Florida area. Elsewhere, 65 mph (105 km/h) winds were recorded. At Mayport, winds were sustained at 43 mph (69 km/h). In northern portions of the state, peak rainfall totals ranged from 5 to 7 in (130 to 180 mm), much of which was associated with an intense convective band to the north and east of the cyclone's center.[15] One tornado, ranked F1 on the Fujita scale, touched down near Savannah, Georgia.[16] Power outages were mostly minor and scattered.[8] Tides generally ran under 3 ft (0.91 m) above normal; combined with high winds, the tides contributed to severe and widespread beach erosion along the eastern coast of central Florida, threatening structures at times.[8] A large, $500,000 beach restoration fill was washed away. Additionally, segments of State Road A1A were damaged. On Hutchinson Island, many eggs and nests of Caretta caretta and Chelonia mydas, respectively, were destroyed. One man was electrocuted as a result of the storm near Orlando.[17] Another man was injured while attempting to land his plane in high winds.[18] Throughout the state, overall damage was generally insignificant.[17]

The storm also dropped heavy precipitation along the coasts of Georgia, South Carolina, and North Carolina, with sporadic showers in parts of Virginia.[19] Offshore, swells of 12 to 15 ft (3.7 to 4.6 m) extensively damaged a wooden ship, the Phoenix. The vessel "barely escaped destruction", though a crew member suffered a cracked rib.[20] Across its path, Isidore was estimated to have inflicted $1 million in damage.[5]

• List of Florida hurricanes
• List of Atlantic hurricanes

• HPC rainfall data
• NHC Preliminary Report