Anegada Passage Southward to 17N Marine Forecast
| Rest Of Today...Southwest Winds 5 To 10 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Isolated Showers. |
| Tonight...West Winds 5 To 10 Knots. Seas 2 To 4 Feet With Occasional Seas Around 5 Feet. Dominant Period 11 Seconds. Isolated Showers. |
| Thursday...West Winds 10 To 15 Knots. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet. Dominant Period 12 Seconds. Isolated Showers. |
| Thursday Night...North Winds 10 To 15 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 12 Seconds. Scattered Showers. |
| Friday...North Winds 10 To 15 Knots, Becoming Northeast. Seas 5 To 7 Feet With Occasional Seas Up To 9 Feet. Dominant Period 11 Seconds. Isolated Showers. |
| Saturday...Southeast Winds 5 To 10 Knots. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet. Dominant Period 12 Seconds. Isolated Showers. |
| Sunday...South Winds 5 To 10 Knots, Becoming East. Seas 5 To 7 Feet With Occasional Seas Up To 9 Feet. Dominant Period 14 Seconds. |
| Area Forecast Discussion National Weather Service San Juan PR 410am AST Wednesday July 22 2026 .Short Term(Today through Friday)... Issued at 357am AST Wednesday July 22 2026 An active weather pattern will unfold across the local region today, driven by an upper-level trough and an induced surface trough to our north that continues to pull a surge of tropical moisture over the area. Precipitable water (PWAT) values will range between 1.80 and 2.00 inches, supporting scattered convective development. Strong daytime heating, sea breeze convergence, and dynamic upper-level divergence will trigger afternoon showers and thunderstorms, primarily over the interior and west/northwest Puerto Rico. Heavy downpours will present a localized urban and small stream flooding risk. Passing showers will continue to affect the U.S. Virgin Islands and eastern coastal areas through midday, with a slight chance for thunderstorm development. In addition to the rainfall risk, hot and humid conditions will prevail today and early Thursday. The combination of warm 925 mb temperatures near 23C and light to moderate southeasterly wind flow will limit low-level cooling, causing heat indices to reach or exceed 108F to 111F across the lower elevations and urban areas of the islands, making Heat Advisories likely both today and Thursday. From late tonight into Thursday, a dense Saharan Air Layer (SAL) will engulf the northeastern Caribbean, bringing a sharp reduction in moisture content (PWAT (Precipitable Water) dropping to near 1.25 inches), strong mid-level cap, and hazy skies. This hostile air mass will restrict Thursday's convective activity to brief, isolated afternoon showers in western Puerto Rico while degrading air quality. The Saharan dust plume will retreat westward by Friday as another surge of tropical moisture from a weak tropical wave pushes into the local area. Precipitable water levels will briefly recover to near 2.00 inches alongside eroding the mid-level cap. This rapid moisture return will re-establish a typical seasonal convective setup, bringing passing morning showers to the U.S. Virgin Islands and eastern Puerto Rico, followed by scattered afternoon showers and thunderstorms focused across the interior and western Puerto Rico. .Long Term(Saturday through Wednesday)... Issued at 357am AST Wednesday July 22 2026 A surface high pressure over the Atlantic will generally dominate during the period with lows staying mainly over the western to northern Atlantic, this will promote breezy easterly flow on Saturday and east-southeasterly flow late Sunday onwards, with breezy conditions persisting at least through the weekend. However, most available moisture will remain below 800 mb through Sunday afternoon with precipitable water (PWAT) values staying below normal to normal range, with above normal values possible during afternoon convection. Temperatures at 500 mb will remain around -7 to -8 °C, at normal to below normal, and will support isolated t-storms associated with afternoon convection (due to diurnal heating, sea breeze convergence and local effects). Showers will also be steered towards the islands from time to time especially during the morning and night hours, however a limited flooding risk can occur mainly during afternoon convection over interior to W and NW Puerto Rico. Looking ahead from late Sunday into Wednesday, recent model guidance indicates a tropical wave-driven moisture surge will affect the region, with PWAT (Precipitable Water) levels to normal and above-normal thresholds. Furthermore, an upper-level low positioned over the islands from Saturday through Monday will maintain lower 250 mb heigheights and cooler 500 mb temperatures with both trending near or below seasonal norms. Available moisture will in turn reach the mid to upper levels through at least early Wednesday. These factors combined will foster more favorable upper-level dynamics, increasing the likelihood of shower activity and isolated thunderstorm development across the forecast area. Drier air will start to filter over the area Wednesday night. Moderate to locally high concentrations of Saharan Dust will continue to filter over the islands through most of the weekend with concentrations decreasing to low (with isolated patches of moderate concentrations from time to time) late Sunday through Tuesday. Current guidance suggests that moderate to high concentrations of Saharan Dust will then return by Wednesday. Throughout the majority of the forecast period, warm to hot conditions will persist, bringing a limited to elevated risk of heat to coastal, urban and lower elevations. To mitigate the danger of heat-related illnesses, both visitors and residents are advised to keep following heat safety guidelines. Marine Issued at 357am AST Wednesday July 22 2026 An induced surface trough will continue moving west across the local waters today while Atlantic high pressure gradually rebuilds. East to southeast winds will gradually become established through the day, around moderate to locally fresh speeds. Scattered showers and isolated thunderstorms will persist across the local waters, with locally higher winds and seas possible in and near stronger convection. By Thursday, a drier air mass accompanied by moderate concentrations of Saharan dust will overspread the region, resulting in hazy conditions and reduced visibility. A tropical wave approaching the Lesser Antilles will increase moisture across the local waters by Friday, leading to increasing shower activity and strengthening east winds. Beach Forecast Issued at 357am AST Wednesday July 22 2026 A low risk of rip currents will persist today across the local beaches. However, life-threatening rip currents can still occur, especially near groins, jetties, reefs, and piers. Beachgoers should continue to exercise caution when entering the water. A moderate risk of rip currents is anticipated by Thursday into the weekend along the northern and eastern beaches of Puerto Rico, Vieques, Culebra, and the U.S. Virgin Islands. Under a moderate risk, life- threatening rip currents are possible, beachgoers are urged to exercise caution. As a surface trough continues moving across the region today, showers and thunderstorms will remain possible. If thunder is heard, seek shelter immediately inside of a building. Another beach hazard today will be the heat. An elevated heat risk is expected along coastal areas of the islands. Stay hydrated by drinking plenty of water. .SJU WATCHES/WARNINGS/ADVISORIES... PR... Heat Advisory from 10am this morning to 4pm AST this afternoon for PRZ001>005-007-008-010>013. VI... Heat Advisory from 10am this morning to 4pm AST this afternoon for VIZ001-002. AM...None. |
San Juan Radar
Southeast Radar