The National Weather Service in San Juan forecasts that Puerto Rico will see variable conditions and increased rain activity on Friday, as abundant tropical moisture favors showers and some thunderstorms. Thursday remained relatively calm with partly to mostly cloudy skies, though a cluster of strong thunderstorms developed over the Mona Passage in the early hours, bringing only a few weak showers to the west coast with minimal rain accumulation.
High temperatures ranged from the upper 80s to low 90s Fahrenheit in the lowlands, and from the upper 70s to low 80s in the highest mountains. Overnight Thursday into Friday morning, a trough will favor isolated showers and thunderstorms over Caribbean waters moving toward the south and southwest coasts. On Friday, passing showers will affect eastern Puerto Rico and the US Virgin Islands overnight and in the early morning, with showers developing in the afternoon over the interior, north and west of the island.
While winds will move rains along relatively quickly, some showers could persist and leave additional accumulation, particularly in western and northern sectors. Precipitable water values between 2.10 and 2.20 inches support the rainy pattern. The NWS warns of possible urban and small-stream flooding, rapid river rises, localized flash flooding and landslides where soils are saturated.
Warm, humid conditions continue with possible heat effects, and the rainy pattern could extend into Saturday.