AFDSJU Area Forecast Discussion National Weather Service San Juan PR 215 PM AST Sat Dec 13 2025 ...New SHORT TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 215 PM AST Sat Dec 13 2025 * Choppy to rough seas and life-threatening rip currents are expected to continue through the weekend across the islands. * Increased moisture due to a trough will continue to reach the islands for the rest of today into Sunday, increasing passing shower activity. Limited afternoon convection possible over northwest PR. * For the U.S. Virgin Islands, passing showers will increase in frequency once again for the rest of today through Sunday. * Breezy to locally windy conditions are expected to continue tomorrow. * The approach of a frontal system and its associated upper-level trough over the western Atlantic will promote unstable conditions during the first half of the workweek. && .Short Term(This evening through Monday)... Issued at 215 PM AST Sat Dec 13 2025 Early this morning, isolated to scattered showers moved across windward portions of the islands, followed by a patch of drier air that resulted in tranquil conditions through midday. Afterward, moisture content gradually increased, bringing additional fast- moving showers with no significant impacts. Daytime highs reached the mid to upper 80s, with some coastal stations reporting low 90s. Across the higher elevations of Puerto Rico, temperatures remained in the 70s to low 80s. As anticipated, breezy winds persisted, with several surface stations reporting sustained winds of 12 to 20 mph and gusts between 25 and 30 mph from the east to southeast. For the rest of the afternoon, a variable weather pattern is expected to continue, with breaks and periods of fast-moving scattered to numerous showers across the islands. This activity is associated with a surge of moisture from a weak trade-wind trough moving through the area. Conditions are expected to become wetter by late this afternoon and tonight across the U.S. Virgin Islands, most coastal areas of northern and southern Puerto Rico, and the eastern half of Puerto Rico as the aforementioned trough crosses the local area. Recent satellite-derived PWAT data indicate values near 1.8 to 2.0 inches, which are above normal based on climatological data. As a result, there is a limited to elevated flood risk tonight across eastern Puerto Rico and the U.S. Virgin Islands as an advective pattern becomes established. Ponding of water on roads and in poorly drained areas, as well as urban, roads, small-stream, and wash flooding, are possible. By Sunday, PWAT values are expected to drop notably below normal as a drier and more stable air mass moves in from the east. This will allow for a mostly sunny day with only isolated showers (020%), although breezy winds are expected to persist, particularly across coastal areas. By Monday, lighter winds are forecast, and moisture content will gradually increase again late Sunday night into Monday. Scattered showers (30 to 50%) are forecast to increase again as the synoptic setup, affected by a pre-frontal trough, starts to become more favorable for rainfall. && .LONG TERM...(Tuesday through Saturday)... Issued at 345 AM AST Sat Dec 13 2025 The approach of a frontal system and its associated upper-level trough over the western Atlantic will promote unstable conditions during the first half of the long term period. Normal to slightly above-normal precipitable water content (PWAT) of 1.75 to 1.90 inches will enhance the potential for shower development across the region. Showers are most likely over portions of eastern Puerto Rico and the U.S. Virgin Islands during the overnight and morning hours, followed by afternoon showers over portions of central and western Puerto Rico. During this period, the 500 mb temperatures are expected to drop into the -6C to -7C range, meaning the potential for afternoon thunderstorms, particularly across western Puerto Rico, cannot be ruled out. At the surface, a strong high-pressure system located over the central Atlantic will maintain an east-southeasterly wind flow across the area, promoting slightly higher than normal temperatures throughout the week. However, by the second half of the long-term period, another high-pressure system is expected to build over the western Atlantic behind the frontal system. By then, winds are expected to shift from the northeast, leading to cooler temperatures into the northeastern Caribbean region. && .AVIATION... (18Z TAFS) Issued at 215 PM AST Sat Dec 13 2025 VFR conditions for the terminals. E-SE winds at 13-20 kts, with gusts up to 23-30 kts through 13/23Z, decreasing after. An increase in VCSH/-SHRA (due to a weak surface trough) is forecast during the afternoon to overnight hours, these can promote tempo MVFR conditions to brief IFR conditions over eastern terminals. Isol VCTS/-TSRA also possible, through 14/07Z. Winds will increase again after around 14/13-14Z to 12 to 18 kt from the E-SE, with higher gusts and sea breeze variations. && .MARINE... Issued at 215 PM AST Sat Dec 13 2025 A surface high-pressure system will continue to build near the Azores through the weekend, promoting moderate to fresh east to southeast winds across the local waters. Increasing winds and a fading long-period northerly swell will result in choppy to rough seas, mainly across the Atlantic waters. Small Craft Advisories remain in effect at least through Sunday afternoon across the offshore Atlantic waters. A cold front and another surface high- pressure system will move from the western Atlantic into the central Atlantic early next week, weakening the pressure gradient and allowing for gentle to moderate winds through Tuesday. By midweek, increasing winds and a northwesterly swell will deteriorate marine conditions once again. && .BEACH FORECAST... Issued at 215 PM AST Sat Dec 13 2025 A fading, long-period northerly swell will create life-threatening rip currents along the north and east facing beaches of the islands, where a Rip Current Statement remains in effect at least through Sunday morning. Beachgoers are urged to avoid swimming under these conditions. The west and south-facing beaches of the islands will have a moderate risk of rip currents tonight. By Sunday and early next week, a low to moderate risk of rip currents is expected to dominate, with beach conditions deteriorating again by midweek as a northwesterly swell spreads across the local Atlantic waters. For specific location information, please visit weather.gov/beach/sju. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through late tonight for PRZ001-002-005- 008. High Rip Current Risk until 6 PM AST this evening for PRZ012. VI...High Rip Current Risk until 6 PM AST this evening for VIZ002. AM...Small Craft Advisory until 5 PM AST Sunday for AMZ711. && $$