Hurricane Season runs from June 1-November 30
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646 FXCA62 TJSJ 041742 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 142 PM AST Tue Nov 4 2025 ...New SHORT TERM, AVIATION, MARINE, BEACH FORECAST... .KEY MESSAGES... Issued at 138 PM AST Tue Nov 4 2025 * This afternoon, a few showers and isolated thunderstorms may form over the interior and southwest, but activity should be brief due to drier air moving in. * On Wednesday and Thursday, winds will shift from the east to east- southeast, bringing more moisture and a better chance for afternoon showers across the interior and western Puerto Rico. * For the U.S. Virgin Islands, mostly fair weather is expected with a few quick passing showers. * A northerly swell arriving later this week will increase the risk of dangerous rip currents, especially along the north- facing beaches of Puerto Rico, Culebra, St. Thomas, and St. John. && .Short Term(This evening through Thursday)... Issued at 138 PM AST Tue Nov 4 2025 During the morning hours, brief showers affected eastern and northeastern Puerto Rico under a northeast wind flow. This wind pattern was driven by an induced surface trough with axis located near the Leeward Islands, gradually moving westward toward the local area. Rainfall accumulations were light, generally under 0.05 inches. Satellite imagery showed patches of low clouds moving inland, while most areas experienced partly cloudy skies and fair weather conditions. The latest GOES-19 Total Precipitable Water (TPW) imagery shows a dry slot just ahead of the trough axis extending over the U.S. Virgin Islands, Vieques, and Culebra, with PWAT values dropping near 1.0 inch, almost two standard deviations below climatological normals. This area of subsidence and dry air will move over Puerto Rico this afternoon, temporarily suppressing deep convective development and limiting the duration of afternoon showers. Despite the drier air intrusion, the mid- to upper-level trough situated just south of or over the region, combined with surface heating, sea breeze convergence, and lingering low-level moisture, will still promote the development of isolated to scattered afternoon showers and thunderstorms across the interior, drifting southward into the southwestern municipalities. However, due to the influence of the dry slot, this activity is expected to be short-lived and less organized. By this evening and into Wednesday, model guidance indicates a significant increase in moisture, with PWAT values rising to around 2.0 inches, approaching or slightly exceeding climatological normals. As this occurs, winds will veer from the east to east- southeast, establishing a warmer and more humid flow across the region. This change will favor more persistent afternoon convection on Wednesday, particularly across the interior and western Puerto Rico, supported by local sea breeze and orographically driven convection. Some of these showers could produce locally heavy rainfall and minor flooding in low-lying or poorly drained areas. By Thursday, a similar pattern will persist, though with slightly less moisture availability, leading to more localized shower activity. The east-southeast wind flow will promote warm air advection, with 925 mb temperatures forecast to reach near or slightly above normal values. As a result, heat index values could rise to near Heat Advisory levels, especially across urban and coastal areas, though overall values are expected to remain just below advisory criteria. && .Long Term(Friday through next Monday)... Issued at 522 AM AST Tue Nov 4 2025 A surface high pressure system over the northern Atlantic will gradually move eastward during the long term period as upper lows move out of northeastern America. This high will generally be over the central to eastern Atlantic by the end of the period. A weak mid level ridge is also expected to persist north/northeast of the region while upper level ridging will continue at or near the region. Patches of both moisture and drier air will filter in and out of the local area throughout the rest of the week under the easterly to then southeasterly steering flow. Precipitable water (PWAT) values are forecast to fluctuate between below normal to normal values late in the week. This will promote a seasonal pattern of passing showers over windward sectors of PR/USVI during the morning and overnight hours with afternoon showers and t-storms possible over mainly western/northwestern Puerto Rico, as diurnal heating, sea breeze convergence, and orographic effects promote this convection and a limited flooding risk. Up to a limited heat risk is likely to persist during the rest of the week. According to the latest guidance, available moisture will mostly be confined to the lower levels throughout the period. The latest model guidance has backed off on the intensity and PWAT values of the, mentioned in previous discussions, tropical wave over our area during the weekend. Southeasterly steering flow will continue to steer moisture from the wave over our area but with up to seasonal PWAT values while deeper moisture remains over the offshore waters. This can still promote up to breezy southeasterly steering flow over southern windward sectors. Patches of both humid and drier air will to filter in and out of the local area early next workweek under southeasterly steering flow, with current model guidance suggesting a patch of drier air moving in to end the period Tuesday afternoon and evening. && .AVIATION... (18Z TAFS) Issued at 138 PM AST Tue Nov 4 2025 Prevailing VFR thru prd. Brief SHRA/VCTS psbl near TJPS this aftn. VCSH expected aft 04/23Z at TJSJ/TIST/TISX as an induced sfc trough approaches. SHRA/VCTS expected at TJPS/TJBQ aft 05/17Z. Winds NE 1015KT with gusts up to 20KT, bcmg light/vrb aft 04/23Z and shifting ESE aft 05/15Z. && .MARINE... Issued at 138 PM AST Tue Nov 4 2025 A weak surface high pressure over the central Atlantic will promote light to moderate easterly winds for the next several days. A surface low moving over the northwestern Atlantic will generate a northerly swell that will build seas to around 6 feet or higher across the Atlantic waters and passages late in the week. && .BEACH FORECAST... Issued at 138 PM AST Tue Nov 4 2025 A moderate risk of rip currents will continue through tonight for the northern and eastern beaches of Puerto Rico and the northern coast of Culebra. Elsewhere, including Vieques and the U.S. Virgin Islands, the risk remains low. By mid to late week, a weak northerly swell will begin to affect the local Atlantic waters and northern coastlines. This will lead to a gradual increase in surf height and an expansion of the moderate rip current risk to include western Puerto Rico, Vieques, and portions of the U.S. Virgin Islands. A high risk of rip currents is anticipated by Friday for northern exposed beaches, including Puerto Rico, Culebra, St. Thomas, and St. John, as the swell peaks. Beachgoers should exercise caution and remain alert to evolving coastal conditions. For additional information and updates, visit weather.gov/beach/sju. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ .MORNING CREW...CVB/RVT
