AFDSJU Area Forecast Discussion National Weather Service San Juan PR 353 AM AST Wed Mar 25 2026 ...New SHORT TERM, LONG TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 349 AM AST Wed Mar 25 2026 * Unsettled weather across Puerto Rico today, with periods of showers and isolated thunderstorms, particularly during the afternoon hours, leading to localized ponding of water in urban and low-lying areas. * More unstable conditions expected from Thursday into Friday across the islands, as a wetter and more dynamic pattern increases the potential for widespread showers, thunderstorms, and periods of moderate to heavy rainfall. * Moderate risk of rip currents across northern and exposed beaches, with hazardous marine conditions promoting life- threatening currents in the surf zone. * Variable weather conditions across the U.S. Virgin Islands, with passing showers at times, but overall limited duration of rainfall activity. && .Short Term(Today through Friday)... Issued at 349 AM AST Wed Mar 25 2026 A fairly active weather pattern was observed overnight, with persistent showers from Luquillo westward into Morovis. Showers were strong, especially around 12 AM across Corozal, Morovis, Naranjito, and along Rio Grande and Canovanas. By 2 AM, showers had diminished across the interior sections, but were still spreading northward into Dorado, Toa Alta, Manati, and Vega Baja. This increase in showers led to rises along small streams across most of the affected municipalities. Several flood advisories and warnings were in effect from late night into the early morning hours. As of 3 AM, the bulk of the showers was affecting municipalities from Manati eastward into the San Juan area. Rainfall accumulations were significant across most of the interior areas; radar estimates ranged from 2 to 5 inches, with the highest amounts in Corozal, Morovis, and Naranjito, where estimates reached 9 inches. Overnight temperatures were in the low 60s across the mountain areas, with some upper 50s due to the persistent shower activity, while coastal areas remained in the mid-70s. For today, a similar weather pattern is expected, with a mid- level closed low promoting instability and favorable conditions for a convective pattern, leading to the development of strong showers across the region. At the surface, winds will remain from the east-southeast in response to a combination of a surface high pressure extending from the Central Atlantic into the Caribbean and an elongated surface trough. All that, and instability aloft from a 250 MB +80 knots jet stream will result in another active day. Therefore, residents and visitors can expect moderate to strong showers in the northeastern sections in the morning, followed by deep convection across the northwestern quadrant. With the heaviest showers, urban flooding is expected along with rapid rises in small streams across the interior and western PR. On Thursday into Friday, the overall synoptic pattern is forecast to transition to a more unstable and dynamically favorable regime across Puerto Rico and the U.S. Virgin Islands, driven by a deep upper-level trough interacting with a strengthening subtropical jet. This interaction will result in a jet streak exceeding 100 knots across the region, enhancing upper-level divergence and promoting large-scale ascent, which will in turn support a more active convective pattern across the islands. Model guidance indicates a notable cooling aloft, with 500 mb temperatures decreasing to around -9 to -10 C, contributing to increased instability, while a deep layer of moisture will be present as relative humidity values between 850 and 500 mb rise to levels exceeding two standard deviations above climatological normals, indicating an anomalously moist column. At the surface, precipitable water values are expected to range between 1.75 and 1.90 inches, near the 75th percentile for this time of year, providing sufficient moisture for widespread shower and thunderstorm development. Overall, this combination of strong upper-level forcing, increased instability, and abundant moisture will support a wetter and more active weather pattern, with an increased potential for periods of moderate to heavy rainfall, particularly during the afternoon and evening hours, along with an elevated risk of urban and small stream flooding in susceptible areas. && .Long Term(Saturday through Wednesday)... Issued at 349 AM AST Wed Mar 25 2026 A mid- to upper-level low will move northeast of the northeastern Caribbean between Saturday and Sunday. This feature will induce trade wind perturbations that will periodically move across Puerto Rico and the U.S. Virgin Islands, promoting passing showers, particularly across windward areas. Expect a variable pattern through the weekend, with a mix of sunshine and brief periods of showery weather, mainly during the overnight and morning hours as these disturbances advect across the region. During the afternoon hours, local effects and sea breeze convergence will support isolated to scattered convection, mainly across the interior and southwestern Puerto Rico. From Monday through midweek, a mid- to upper-level trough interacting with an approaching frontal boundary will promote a more unsettled, wetter pattern across Puerto Rico and the U.S. Virgin Islands. Increasing moisture and instability will support a higher coverage of showers and thunderstorms. Breezy to locally windy conditions are also possible as winds strengthen behind the frontal boundary. Coastal conditions will deteriorate during this period. A long- period northerly swell arriving late Monday night could produce dangerous breaking waves and hazardous coastal conditions through at least midweek, peaking around Tuesday. The potential impacts for the first part of the holiday week include urban and small-stream flooding, a limited risk of flash flooding, isolated thunderstorms with lightning, breezy to windy conditions, life-threatening rip currents, high surf, and possible coastal flooding along vulnerable north- and west-facing coastlines. && .AVIATION... (06Z TAFS) Issued at 349 AM AST Wed Mar 25 2026 Mainly VFR conditions are expected across all terminals; however, VCSH and SHRA will persist along TJSJ until 25/15Z. Brief MVFR to IFR conditions are anticipated across TJSJ and TJBQ from 25/16Z to 25/21Z due to passing SHRA, with lower CIGS and reduced VIS possible. Shower activity developing across the interior and western mountains will result in cloud coverage affecting FL020 to FL060. Winds will remain generally from the E to ENE at around 1015 knots, with higher gusts near shower activity. && .MARINE... Issued at 349 AM AST Wed Mar 25 2026 A weak surface high pressure over the southwestern Atlantic will merge with a stronger high pressure over the north central Atlantic by the end of the workweek. This will promote light to moderate trades for the next several days. Seas will remain at 5 feet or less through the weekend. Late in the weekend and into early next week, a large swell is forecast to build seas up to 10 feet across the Atlantic waters and passages. Also, winds will increase around 20 knots due to an approaching front and stronger surface high pressure developing over the western Atlantic. && .BEACH FORECAST... Issued at 349 AM AST Wed Mar 25 2026 A moderate risk of rip currents is expected to prevail through the weekend across the north and east facing beaches of Puerto Rico, and across the U.S. Virgin Islands. A moderate risk means that life- threatening rip currents are possible in the surf zone, as rip currents can still occur near groins, jetties, reefs, and piers. By early next week, a large northerly swell and increasing winds will cause large breaking waves that can lead to high surf conditions and minor coastal flooding along the Atlantic coastlines of the islands. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$