543 FXCA62 TJSJ 062050 CCA AFDSJU Area Forecast Discussion...CORRECTED National Weather Service San Juan PR 450 PM AST Sun Jul 6 2025 .KEY MESSAGES... * Normal to above normal temperatures will continue each day and a limited heat risk will persist for the lower elevations and urban areas of the islands. * Local and diurnal effects will cause showers with isolated thunderstorms to develop over portions of the Cordillera and western PR during the next few days. * Hazy skies will return late in the workweek due to Saharan dust. && .SHORT TERM...Tonight through Tuesday... Sunny to partly cloudy and hazy skies prevailed once again across Puerto Rico and the U.S. Virgin Islands today. Diurnally induced afternoon showers and isolated thunderstorms developed over the Cordillera and western PR. However, rainfall accumulations were just under half an inch of rain by 2 PM AST. Maximum temperatures were from the mid-80s to the low 90s across the lower elevations of the islands, and from the upper-70s to mid-80s across the higher elevations of Puerto Rico. The wind was from the east between 12 and 16 mph with sea breeze variations and higher gusts across coastal areas. For the rest of the short-term period a similar weather pattern is expected each day. A mid-to upper-level ridge building from the east will promote relative stable conditions aloft. However, trade wind perturbations will bring an increase in passing showers at times each day across the USVI and eastern sections of PR during the nighttime. Then, the available moisture content will combine with local and diurnal effects to trigger afternoon showers with isolated thunderstorms over portions of the Cordillera and western PR. Normal to above normal temperatures will continue each day and a limited heat risk will persist for the lower elevations and urban areas of the islands. .LONG TERM...Wednesday through Sunday... /From Prev Disc issued at 500 AM AST Sun Jul 6 2025/ A trade wind perturbation will affect the region Wednesday, bringing brief periods of enhanced moisture and localized showers. Following this, a weak tropical wave will cross the area Thursday into Friday, steered westward by a strong Bermuda-Azores High. A wind surge will then bring breezy to windy conditions Friday into the weekend, with 700 mb winds peaking near 3540 knots. This pattern will support enhanced low-level moisture transport, though mid- to upper-level dryness and a strong trade wind cap inversion will limit deeper moisture availability and convection. Dry air above 850 mb will persist due to subsidence from mid-level ridging and later reinforced by a Tropical Upper-Tropospheric Trough (TUTT) expected to cross the region Saturday. The most significant drying will occur into early Sunday, with precipitable water (PWAT) falling well below climatological norms. Limited phasing of moisture and instability will restrict widespread or organized convection; however, some afternoon convection remains likely each day following the general wind flow and driven by diurnal heating and local effects. Activity may increase late Sunday as the TUTT shifts west and PWAT returns to typical levels. A moderate to high Saharan Air Layer (SAL) event is anticipated from Thursday onward, coinciding with the drying trend and strengthening winds. This will contribute to hazy skies, reduced visibility, and overall atmospheric stability. Winds will generally flow from east to east-southeast, shifting briefly to east-northeast Saturday night into Sunday as the surface high repositions over the western Atlantic. Temperatures will remain near seasonal norms, with Friday likely the warmest day due to the strongest southeasterly flow component. Except for excessive rainfall hazards, all other weather hazardsincluding periods of excessive heat, gusty winds, and isolated afternoon lightningare possible through the long-term period. && .AVIATION... (18z TAFs) Mainly VFR conditions expected across all terminals during the next 24 hours. However, SHRA/TSRA in and around TJPS/TJBQ may cause brief MVFR cigs thru 06/22z. Also, SHRA en route from the Leeward Islands should move over the USVI terminals between 06/20z-07/03z, this may cause brief MVFR cigs. The 06/12z TJSJ sounding indicated east winds up to 18 kt blo FL050. && .MARINE... Moderate easterly winds will prevail today, but local effects will lead to choppy seas near coastal areas of northern Puerto Rico, prompting small craft operators to exercise caution. Moderate to locally fresh winds will return tonight and persist over the next few days, expanding the area where caution is advised. Saharan dust will keep skies hazy today, with another event expected later in the workweek. Afternoon thunderstorms may affect coastal waters and local passages, particularly near western Puerto Rico, each day. In addition, tropical waves approaching Tuesday and Thursday will likely increase the chances for showers, thunderstorms, gusty winds, and locally higher seas. && .BEACH FORECAST... A moderate risk of rip current is expected across the northern beaches of Puerto Rico on Monday, and extending into the east and southeast beaches and across St. Croix from Tuesday onward. && .FIRE WEATHER... A Fire Danger Statement is in effect through late this afternoon across southern PR. Winds speeds reached 16 mph in Cabo Rojo and the RH dropped just under 55% for 2 hours during the mid-morning hours. However, showers were developing early in the afternoon along portions of the Cordillera and southwestern PR. This will cause RH levels to recover and the fire danger threat to decrease in general. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ DSR/GRS
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