The National Weather Service (NWS) warned Thursday of the possibility of heavier precipitation in Puerto Rico and the United States Virgin Islands (USVI) over the next few days due to a combination of lows in the middle and upper layers of the atmosphere and higher than normal humidity levels caused by from an almost stationary front.

The situation creates ideal conditions for thunderstorms to develop, especially between today and Saturday morning.

Rainfall accumulations of between 3 and 4 inches were expected to occur in areas of northern and eastern Puerto Rico as well as Vieques, Culebra and the USVI, with locally higher amounts reaching up to 6 inches in some areas. Rainfall accumulations of between 1 and 3 inches were expected across the rest of the region.

Due to the possibility of persistent and heavy rainfall, the Flash Flood Warning should remain in effect until Saturday morning. The warning warned of the risk of flash floods and river flooding that could reach flooding, as well as the possibility of landslides in areas with steep terrain.

In addition to the rainfall, a high risk of dangerous marine conditions, including strong rip currents, was also expected at least over the weekend. The NWS issued a small boat and heavy surf warning for north-facing beaches in Puerto Rico through at least Friday afternoon.

The public was urged to stay informed about the potential risks of excessive rainfall and hazardous ocean conditions through the NWS Experimental Graphical Hazard Weather Outlook and to take precautions in the event of flooding or rip currents on beaches.

The extended rainfall warning came as the NWS issued multiple flood warnings for various areas of Puerto Rico on Thursday, as heavy rains were caused by strong storms that hit much of the island.

The rains caused flooding in urban areas and small streams, affecting areas with poor drainage and increasing river and stream levels.

An accumulation of 3 to 5 inches of rain was recorded in the municipality of Humacao by midday Thursday, mostly in areas near Quebrada Los Muertos and sectors such as Urb Villa Oriente. Local authorities reported flooding on the PR-909 highway.

Meanwhile, in Maunabo, trained weather observers reported rain accumulations of 5 to 10 centimeters, with additional rainfall of up to 7 centimeters expected. Areas such as Emajagua, Playita and Palo Seco experienced rising streams and possible street flooding due to soil saturation.

The NWS maintained a flash flood warning for the Ceiba and Fajardo areas until this morning. Up to 6 inches of rain was recorded in some areas, impacting major roads such as Lauro Piñeiro Avenue and PR-3 in areas such as Roosevelt Gardens and Colonia Santa María.

Yabucoa experienced up to 5 inches of rainfall, affecting areas such as Jardines de Yabucoa and sections of the PR-901 and PR-3 highways. Local authorities reported active flooding in these areas and warned that the risk of flash floods remained as long as the rains continued.

The NWS urged residents in affected areas to avoid flooded areas and follow guidance from local authorities.