Relentless rain sparks dangerous flooding in Puerto Rico, Virgin Islands
Flash flood watches were extended Thursday as rain amounts had eclipsed 8 inches in one location -- and AccuWeather forecasters warn that the life-threatening flooding danger is far from over.
A surge of unrelenting tropical moisture has set up over Puerto Rico and the Virgin Islands late this week, ushering in days of drenching downpours that have caused flooding.
An area of disturbed weather in the southwestern Atlantic Ocean that forecasters are monitoring for potential tropical development is dragging this plume of deep moisture northward from around the equator.
Rain began to fall across western Puerto Rico on Tuesday night. By early Wednesday morning, heavy rainfall had arrived for the eastern portion of the territory as drenching thunderstorms pounded the region. Rainfall amounts at midweek tallied 2-3 inches in eastern Puerto Rico, with an amount of 4.29 inches recorded in St. Thomas. This ranked as the reporting station's twenty-second wettest day on record. In just 12 hours, Puerto Rico's capital city of San Juan had picked up just over 2 inches (50 mm) of rain.
Flooding in Guayama, Puerto Rico on October 27, 2022.
On Thursday, as much as 8.50 inches of rain was reported at Jiménez, Puerto Rico, in the northeast part of the island. A resident of Guayama in southeast Puerto Rico shared photos of flooding on Twitter, showing water moving over a bridge previously washed out by Hurricane Fiona. Rain at a nearby amateur weather station was measured at 8.29 inches.
The Rio Blanco at Florida, Puerto Rico experienced moderate flooding Wednesday and Thursday, setting its third-highest stage on record yesterday afternoon, at 11.94 feet, and the fourth-highest reading this afternoon, according to the United States Geological Service. The gauge was installed in 2019, after Hurricane Maria in 2017.
Forecasters say the plume of tropical moisture is expected to remain aimed at the region into the end of the week, resulting in more excessive rainfall amounts being tallied. On Thursday morning, the National Weather Service office in San Juan extended their flash flood watch through Friday evening.
Widespread rainfall totals on the order of 3-6 inches (75-150 mm) are set to fall from Puerto Rico to the Virgin Islands through at least Friday morning. Higher amounts are likely in a swath from eastern Puerto Rico through the British Virgin Islands where total amounts of 6-12 inches (150-300 mm) can occur.
This much rain in 48-72 hours can prove to be dangerous almost anywhere across the globe. However, Puerto Rico and the surrounding Caribbean islands are still recovering from a powerful strike by Hurricane Fiona in September and remain vulnerable to heavy rain events.
"Given the damage done and excess rain unleashed by Fiona in September, these areas are already starting at a much lower threshold for significant flooding problems to develop," AccuWeather Senior Meteorologist Tyler Roys cautioned.
In areas that receive the heaviest rainfall by the end of the week, major flooding is likely to develop, and travel may become extremely difficult or even impossible.
Round after round of downpours will almost certainly lead to significant rises in stream and river levels across the region. Smaller streams can quickly overflow their banks and flood low-lying areas, and major rivers are still running at higher-than-normal levels, forecasters say.
During Fiona, a large portion of Puerto Rico lost access to clean drinking water because river levels rose too high for the water filtration systems to handle, according to NPR. If levels rise to dangerous levels this week, similar issues may follow.
In addition to river, stream and flash flooding, mudslides will also be a significant risk for areas encountering the heaviest rain.
"If the pipeline of rain fails to shift in a prompt manner later this week, a life-threatening situation could unfold," AccuWeather Senior Meteorologist Alex Sosnowski warned.
By this weekend, the plume of heaviest moisture is forecast to be disrupted by potential tropical development in the Caribbean Sea. While this shift can end the heaviest rain threat to populated areas of the Caribbean, any lingering storms can hinder cleanup efforts.
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