Tropical Storm Erika was a weak but deadly tropical storm that is regarded as one of the worst natural disasters in Dominica since Hurricane David in 1979. The fifth named storm of the 2015 Atlantic hurricane season, Erika developed from a westward-moving tropical wave while well east of the Lesser Antilles. Hostile conditions, including dry air and wind shear, inhibited significant development, and Erika failed to acquire sustained winds beyond 50 mph (80 km/h). Contrary to predictions of a northwesterly recurvature, the cyclone persisted on a westerly course and passed through the Leeward Islands and emerged over the Caribbean Sea on August 27. Erika succumbed to adverse conditions the following day, dissipating as a tropical cyclone near the Dominican Republic. The remnant system persisted for several more days, moving into the northeastern Gulf of Mexico, before dissipating over Georgia on September 3.
Several islands experienced heavy rainfall during the passage of Erika, especially Dominica. The storm's asymmetric structure, coupled with the mountainous terrain of the island and ample moisture aloft, led to rainfall accumulations up to 33 in (850 mm). With grounds already saturated from antecedent rainfall, tremendous runoff quickly overwhelmed river basins and triggered catastrophic floods. Accompanying mudslides worsened the situation, temporarily damming the rivers before collapsing. Hundreds of homes were left uninhabitable and thousands of people were displaced; the entire town of Petite Savanne was evacuated and subsequently abandoned as a result of the storm. All told, 30 people died across the island in the nation's worst disaster since Hurricane David. The storm's devastating effects in Dominica prompted an influx of international assistance. Aid from multiple nations and intergovernmental organizations poured in to assist victims of the storm. Thousands of homes needed to be built or repaired, including 500–1,000 for the relocation of all of Petite Savanne's residents. Recovery in Dominica was halted in September 2017 by Hurricane Maria, a Category 5 hurricane that brought far greater devastation on the island.
In Guadeloupe, heavy rainfall in the vicinity of Basse-Terre caused flooding and mudslides, forcing roads to temporarily close. Approximately 250,000 people in Puerto Rico were left without electricity. The island experienced US$17.37 million in agricultural damage. In the Dominican Republic, a weather station in Barahona measured 24.26 in (616 mm) of rain, including 8.8 in (220 mm) in a single hour. About 823 homes suffered damage and 7,345 people were displaced. Five people died in Haiti, four from a weather-related traffic accident and one from a landslide. Total damage from Erika is estimated to be over US$500 million, with US$482.8 million in Dominica alone.
Meteorological history
On August 20, 2015, the National Hurricane Center (NHC) began monitoring a tropical wave over western Africa, near the Atlantic shore. The disorganized system emerged over the Atlantic Ocean several hundred miles southeast of the Cape Verde Islands the following day. Moving quickly west, the system bypassed the Cape Verde Islands to the south on August 22, but remained largely disorganized. A sharp trough developed within expanding deep convection on August 23, though a well-defined circulation did not consolidate. Organization of the low improved throughout the day as environmental conditions favored tropical cyclogenesis. The trough acquired gale-force winds the following day and finally developed a closed circulation by 18:00 UTC. The formation of a closed low marked the transition into a tropical cyclone; accordingly, the system was classified as Tropical Storm Erika, the fifth named storm of the annual hurricane season. Upon its designation, Erika was situated roughly 1,035 mi (1,665 km) east of the Lesser Antilles. The storm maintained a brisk westward trajectory, steered by a subtropical ridge to the north.
At the time of Erika's classification, forecast models diverged significantly on the potential future of the storm. Statistical guidance and the HWRF depicted a hurricane while the ECMWF and GFS showed a weaker system due to increasing wind shear. The models that intensified the storm indicated a more northerly track while those that kept it weaker had the system continuing along a westward course. Accordingly, the NHC noted low confidence in their five-day forecast for Erika. This uncertainty ultimately reflected in above-average forecast errors when compared to all tropical cyclones, but roughly average for weak, poorly organized systems. Throughout August 25 and into early August 26, the convective organization of Erika fluctuated due to wind shear and entrainment of dry air, periodically leaving the center of circulation devoid of convection. Early on August 27, Erika managed to intensify slightly, attaining its peak intensity with maximum sustained winds of 50 mph (80 km/h) and a barometric pressure of 1,001 mbar (29.6 inHg). Around 09:00 UTC, the disorganized center of Erika passed near the northern tip of Guadeloupe, before emerging over the eastern Caribbean Sea.
Convection remained poorly-organized and mostly confined to eastern portions of the cyclone, as it traversed the eastern Caribbean Sea. Multiple circulation centers were noted during the overnight of August 27–28, all rotating around a broad general center. One such center moved over St. Croix and produced gale-force gusts. Environmental conditions ahead of the storm became increasingly hostile, and forecasters at the NHC continued to note unusually high uncertainty in their forecasts. Further structural degradation ensued on August 28 as Erika approached the Dominican Republic. Based on data from Hurricane Hunters, Erika degenerated into a broad area of low pressure—no longer meeting the definition of a tropical cyclone—shortly after 12:00 UTC, near the southeastern coast of the Dominican Republic. Operationally, the NHC maintained advisories on Erika until 13:30 UTC on August 29. It was also noted during those advisories that the center was completely devoid of convection, and whatever convection remained was reduced to the eastern half of the system.
Around 21:00 UTC on August 28, the remnants of Erika made landfall along the southeastern coast of the Dominican Republic. The disheveled system emerged over the Windward Passage early on August 29. Thereafter, the system skirted the northern coast of Cuba and entered the Gulf of Mexico on August 31. Turning northward, the disturbance eventually crossed northern Florida on September 2, before dissipating over Georgia on the following day.
Preparations
Caribbean
Various local governments issued tropical storm watches and warnings for their respective nations throughout the duration of Erika. Watches and warnings covered the Lesser Antilles from Guadeloupe northward, almost the entirety of the Greater Antilles, and the Bahamas. The Red Cross opened four shelters to the public across the United States Virgin Islands. The local Health Department also opened special needs shelters on St. Croix and St. Thomas. All non-essential government personnel were given administrative leave on August 27. Owing to rough seas, local ports temporarily closed. Although airports remained open, several airlines cancelled flights. A territory-wide curfew was imposed until the afternoon of August 28.
Schools, ports, and beaches were closed across the Dominican Republic. The Army of the Dominican Republic deployed 275 soldiers and alongside the nation's Air Force, assisted with the evacuation of residents. The Navy was placed on standby for potential search and rescue operations. Officials in Haiti suspended air service, banned highway travel between departments, and ordered small watercraft to remain at port. Evacuation shelters were opened across all departments and 254 prisoners were relocated from Gonaïves to three other facilities.
Florida
On August 28, Florida Governor Rick Scott declared a state of emergency. Despite the storm dissipating shortly thereafter, Scott kept the emergency declaration in place and stated, "This storm has been completely unpredictable the whole time...we will still get a lot of rain and a lot of flooding." Thirty members of the Florida National Guard were positioned while another 8,000 were placed on standby. A collective 17 flights were cancelled at Miami International Airport and Fort Lauderdale–Hollywood International Airport on August 28. Schools in Hendry County preemptively closed for August 31, with officials citing flooding concerns. The National Park Service shut down Biscayne National Park on August 28, and Dry Tortugas National Park and Everglades National Park on August 29. Sandbags were distributed to residents in Doral, Hallandale Beach, Hollywood, and Sweetwater. The
last hurricane to impact the state was Hurricane Wilma in 2005. Since that time, the state's population grew by 2 million with many presumed to have never experienced a hurricane before. Some newer residents remained apathetic over the storm, dismissing it as "another excuse to skip work or school or to party."
Impact
Caribbean
In Guadeloupe, rain totals reached 100 mm (3.9 in) in Basse-Terre while gusts peaked at 100 km/h (62 mph) on La Désirade. Some landslides and flooding were reported, with roads in Basse-Terre temporarily closed. Électricité de France reported that 1,600 customers lost power during the storm. Rough seas in Martinique grounded boats. Landslides and felled trees blocked several roadways across the island. Elsewhere in the Lesser Antilles, effects from Erika were negligible.
The outer bands of Erika brought much needed rain to drought-stricken Puerto Rico; a station in Adjuntas recorded 4.45 in (113 mm) of rain. Tropical storm-force wind gusts, peaking at 59 mph (95 km/h) in Maricao, caused substantial disruption to the power grid, leaving approximately 250,000 people without electricity. Thirty-six homes sustained roof damage across interior locations of the territory and agriculture sustained US$17.37 million in damage.
A weather station in Barahona, Dominican Republic, measured 24.26 in (616 mm) of rain during Erika's passage, including 8.8 in (220 mm) in a single hour. Surrounding areas reported significantly less rain, however. Throughout the country, 823 homes suffered damage and 7,345 people were displaced. Erika blocked over 400 roads and left many power outages. Winds gusts of 50 mph (80 km/h) in Azua caused at least RD$400 million (US$8.91 million) in damage to the banana crop. Heavy rainfall also impacted Haiti, which was still recovering from a catastrophic earthquake in 2010; an estimated 60,000 people remained in emergency housing. Four persons died and eleven others were hospitalized in Léogâne, when a truck crashed into a bus on rain-slicked roads and exploded. A fifth death occurred during a landslide in Port-au-Prince. Two people in the area were injured after a house collapsed.
The remnants of Erika later brought much needed rains to Cuba, which was suffering from its worst drought since 1901.
Southeastern United States
Later, Erika's remnants dropped locally heavy rainfall across Florida, particularly in the Miami Metropolitan Area. A station northwest of Sweetwater observed 9 in (230 mm) of rain. Minor flash flooding left streets in Wynwood impassable. Farther north in Flagler County, scattered thunderstorms produced isolated instances of heavy rain; 2.2 in (56 mm) fell within one hour in Palm Coast. In the greater Jacksonville area, lightning struck the Sally B. Mathis Elementary School, resulting in damage to the air conditioning unit and evacuation of students. In neighboring Georgia, moisture from Erika's remnants fueled scattered severe thunderstorms. Large hail caused US$2.3 million in damage near Woodstock. Strong winds gusting up to 60 mph (97 km/h) accompanied these storms, downing trees and power lines in Cherokee, Polk, and Troup counties. Additional rainfall extended north through the Carolinas.
Effects in Dominica
Although Erika passed well to the north of Dominica as a weak tropical storm, torrential rain associated with the storm impacted the country. Unusually high precipitable water values of 2.6 in (67 mm) were present over the island as Erika moved through. Orographic influence exacerbated rainfall rates, and this was further compounded with the formation of a temporary mesoscale low over the island as the primary circulation of Erika continued west. More than 8 in (200 mm) of rain fell across the entire island in less than 48 hours, with an island-wide average of 24 in (610 mm). During the period of heaviest rain, average rainfall across the entire island exceeded 3.5 in (90 mm) per hour. Rates along the Macoucherie River reached 11 in (270 mm) per hour. The heaviest rain was concentrated around the nation's tallest mountain, Morne Diablotins, where an estimated 31 to 33 in (800 to 850 mm) fell. Rainfall across Morne Diablotin National Park generally exceeded 24 in (600 mm). A secondary peak accumulation of 26 to 28 in (650 to 700 mm) occurred in the southeastern part of the island around Morne Trois Pitons. Observed accumulations include 17 in (430 mm) at Gleau Gommier, 12.62 in (321 mm) at Canefield Airport, and 8.74 in (222 mm) at Douglas–Charles Airport. With grounds already saturated from nearly two weeks of rain prior to Erika, much of the precipitation did not penetrate the surface; in multiple watersheds, runoff exceeded 60 percent of accumulations.
Catastrophic flash flooding and mudslides ensued across the island, resulting in Dominica's worst natural disaster since Hurricane David in 1979. Across the island's rugged terrain, the mudslides temporarily dammed overflowing rivers creating a buildup of water. These earthen dams subsequently collapsed, leading to amplified flooding downstream. Flow rates in these localized events vastly exceeded values expected by International Commission on Large Dams modeling. A post-storm study of 16 rivers on the island revealed peak discharge values in excess of 1,000 m3/s along 5 rivers, with a maximum of 2,876 m3/s along the Malabuka River.