Flash Flood — Southeast, Puerto Rico

2008-09-21 · near Guayama, Southeast, Puerto Rico

Event narrative

Flooding was reported at Barrio Olimpo, Barrio Machete along road 744, Villa Capo along road 179 in Guayama. One resident of was swept underneath an automobile by the river Guamani currents and drowned. Another person suffered a heart attack as he was bailing flood water out of his home.

Wider weather episode

During the three day period of September 21-23, 2008, parts of Puerto Rico suffered from one of the most catastrophic flooding events of the season to date. The flooding affected many municipalities island wide. The torrential rainfall resulted in severe flooding to rivers, streams, and roads, causing sinkholes, land/mudslides, and structural collapses mainly across the southern half of the island. Specifically, the heaviest rainfall, and most severe effects, occurred across the municipalities of Cabo Rojo, Guayama, Humacao, Patillas, Ponce, and Yabucoa, where in some locations, totals approaching 30 inches of rainfall fell in a three-day period, ending at 8 am Tuesday, September 23, 2008.The heavy rainfall and subsequent flooding were a direct result of a large tropical disturbance that moved slowly west across the island. On occasion, tropical disturbances may develop into tropical depressions and, upon further intensification, get named by the National Hurricane Center (NHC) as a tropical storm and/or hurricane. While the National Weather Service (NWS) in San Juan and the NHC closely monitored the system for possible organization into a named storm, multiple reconnaissance flights flown through the disturbance revealed no closed, low-level, surface circulation, which was needed to satisfy the definition of a tropical depression. It was not until 5 pm Thursday, September 25, 2008 when the system, located about 380 miles north northwest of San Juan, Puerto Rico, was named Tropical Storm Kyle. The strongest effects of the tropical disturbance were first felt in Puerto Rico on Sunday, September 21, 2008. The most intense rainfall occurred in the 24-hour period starting at 8 am Sunday, September 21, 2008 through 8 am Monday, September 22, 2008, with the highest rainfall rates occurring during the overnight hours from sunset on Sunday to sunrise on Monday. The largest rainfall amounts for the 24-hour period ending 8 am Monday, September 22, 2008 were 22.03 inches in Patillas, 20.00 inches in Guayama, 16.00 inches in Cabo Rojo, 14.83 inches in Yabucoa, and 10.81 inches in Ponce. For the combined three-day period, some of these numbers increase further with 29.83 inches in Patillas, 21.86 inches in Yabucoa, 20.52 inches in Ponce, and 17.82 inches in Cabo Rojo. Lesser, but just as significant, amounts, ranging from 5-15 inches of rain, fell across much of the island. The torrential rainfall seen across the island was immediately seen across the extensive river network in Puerto Rico. Some rivers, including the Rio Gurabo, saw water levels rise in excess of 25 feet in less than 12 hours. Parts of the island that were spared the worst of the rain include the northern and northwestern coast, were only moderate rain showers were experienced. The total rainfall amounts recorded from this event are unique in that the 29.83 inches seen in Patillas exceeds the weekly total rainfall of 27.13 inches measured in Juana Diaz during the October 1985 flood event. The 24-hour rainfall totals ending at 8 am Monday, September 22, 2008, which encompassed parts of the southeastern section of the island, including the municipalities of Patillas and Guayama, exceeded 200-year 24-hour rainfall totals. Specifically for Patillas, the recorded rainfall amount approaches the 500-year 24-hour rainfall totals. Along the southwestern section of the island, Cabo Rojo's 24 hour rainfall also exceeded the 100-year return period. Across the southern municipalities of Puerto Rico, Ponce and Yauco's 24-hour rainfall rates exceeded the 10-year 24-hour rainfall totals, Juana Diaz exceeded the 25-year rainfall totals, and Yabucoa, along the southeast coast, exceeded the 25-year rainfall totals. The resultant flooding had considerable effects on the local population. Six fatalities were reported, three direct deaths due to drowning, and 3 indirect heart attack deaths related to stress induced flooding. An estimated 630 people in the affected areas were evacuated to shelters. In addition to structural damage caused by the flood waters, agricultural damage was sustained by coffee, plantains, and other minor crops, damage was preliminarily estimated at 23 million. In response to the significant flooding, federal authorities issued a disaster declaration for portions of the island.

View location on OpenStreetMap → (18.0095, -66.1034)

Source: NOAA Storm Events Database, event_id 136745. Narrative written by the NWS forecast office that issued the report.