Hurricane Season runs from June 1-November 30
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000 FXCA62 TJSJ 241954 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 354 PM AST Wed Apr 24 2024 .SYNOPSIS... The influence of a surface trough will continue to impact the local weather conditions. Winds are forecast to become light and easterly tomorrow, promoting slow-moving showers and thunderstorms. With the expected weather, the potential for urban and stream flooding remains elevated through the short-term period. && .SHORT TERM...Tonight through Friday... In the morning, mostly hazy skies prevailed across the islands. Nonetheless, some shower activity filtered along the northeastern sections of Puerto Rico, Culebra, and Saint Croix, with the municipality of Fajardo receiving the heaviest rainfall and accumulations of around an inch. By the early afternoon hours, showers started to form along southern, interior, and eastern sections of Puerto Rico and then spread across the entire island. This rainfall activity promoted another active afternoon in PR. Temperatures-wise, they remained in the 80s along the coastal areas, while over the higher elevations, they stayed in the 70s to low 80s. The latest model guidance continues to indicate the presence of the surface trough near the forecast area. This trough, coupled with the light east-southeast winds, is persisting and is being influenced by an approaching frontal boundary from the northwest. As a result, tonight, we can expect some residual showers of the afternoon convection across the west, along with overnight passing showers, particularly over eastern Puerto Rico and the U.S. Virgin Islands. On Thursday, winds will gradually become more easterly. As mentioned in previous discussions, the surface perturbation will gradually move out of the area from Thursday into Friday. However, a mid- level short-wave trough, along with the aforementioned frontal boundary, will cross the northeastern Caribbean through the end of the week, maintaining or even enhancing unstable conditions across the region. Moisture levels will also remain above normal throughout this period. Overall, wet and unstable weather conditions will prevail for the remainder of the short-term forecast. In other words, expect periods of heavy showers and isolated to scattered thunderstorms across Puerto Rico and the U.S. Virgin Islands. Consequently, the risk of flooding will remain elevated, with the potential for urban and small stream flooding, along with localized flash flooding and landslides. Gusty wind conditions and frequent lightning cannot be ruled out, particularly with the strongest rainfall activity. && .LONG TERM...Saturday through Wednesday.... //from previous discussion// Lingering moisture from a surface trough will continue to produce a pattern of passing showers on Saturday, especially during the morning hours. By later in the afternoon, this moisture will gradually be pushed south of the local region, as a surface high pressure exits the eastern coast of the United States. This surface high will push drier air into the local area and will promote mainly fair weather conditions for most of the long-term period. The drier airmass will lower the precipitable water values to around 1.20 inches from Saturday through Tuesday. Moderate to fresh northeast winds between 15 to 20 mph with higher gusts are expected in response to the surface high as well. Despite of the drier air filtering into the local area, there is the chance for shower development over the local waters at times. These showers may reach the U.S. Virgin Islands and portions of Puerto Rico. In addition, afternoon convection is possible across the southwestern portions of Puerto Rico each afternoon due to the combination of daytime heating and local effects. Wednesday will be a transition day from a dry into a much wetter pattern. A field of moisture is expected to reach the local area from South America increasing the potential for heavy showers and thunderstorms across the region. Daytime temperatures are expected to remain in the mid 80s along the coastal and urban areas of Puerto Rico and the U.S. Virgin Islands, and in the low 80s across the higher elevations. Heat indices will stay in the mid to upper 90s. && .AVIATION... (18Z TAFs) Sfc trough across the area will continue to produce SHRA/TSRA across much of the interior, northern and western sections of PR. This could lead to tempo MVFR conds at TJBQ/TJSJ thru 22z. Elsewhere, VFR conditions should prevail for the rest of the period. HZ due to Saharan dust continues across the northeastern Caribbean but VSBY should remain P6SM. Low-level winds will continue from the SE at 8- 12 kt, bcmg light and variable overnight. Showers are expected to increase once again in and around TIST/TISX btw 25/12-16z. && .MARINE... A small northwesterly swell is expected to arrive later tonight into Thursday. Showers and thunderstorms will continue to affect the local waters for the next few days. Another surface trough will strengthen the easterly winds from Thursday into Friday, before becoming northeast on Saturday under the influence of a surface high pressure moving off the eastern coast of the United States. && .BEACH FORECAST... Breaking waves of around 3 feet will maintain the risk of rip currents generally low tonight. However, will become moderate again tonight for the northern beaches of the local islands. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM...MMC/LIS LONG TERM....GRS AVIATION...DS MARINE/BEACH FORECAST...MMC PUBLIC DESK...MMC/LIS/RC
