000 FXCA62 TJSJ 050845 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 445 AM AST Mon Dec 5 2022 .SYNOPSIS... Expect frequent scattered to numerous trade wind showers streaming across the Atlantic waters into the northern half of Puerto Rico and the northern U.S. Virgin Islands. Elsewhere, expect a mixture of sunshine and passing showers producing minimal impacts. A similar pattern is expected for the next several days, with a drier trend by the end of the week as cool, northern sourced air moves into the region. A northeasterly swell spreading across the Atlantic waters will maintain hazardous marine conditions over the next few days. Mariners and beachgoers should exercise caution as seas and breaking wave heights are reaching in excess of 10 feet. Another strong northeasterly swell is expected by the end of this week. && .SHORT TERM...Today through Wednesday... Short-term dominant features are a nearly stationary developing mid- to-upper level low and surface-induced feature to the northeast, which trough's axis extends southwestward into the northeastern Caribbean region, and a long-period northeasterly swell spreading across the Atlantic waters and local Caribbean passages. These features will maintain hazard risk at limited to significant or high levels for rip currents, marine conditions, and winds throughout the cycle. Today's weather conditions will be dominated by frequent scattered to numerous trade wind showers streaming across the Atlantic waters into the northern half of Puerto Rico, the northern U.S. Virgin Islands, and the local islands. While thunderstorms were excluded from the official forecast, one or two could develop. This activity results from unstable conditions yielded by the developing mid-to- upper level low, which are then pushed southward by increased north- northwesterly winds generated by the tightening of the local pressure gradient from the developing surface-induced feature. Ponding of water on roadways and poorly drained areas is likely, while localized urban and small stream flooding is possible, mainly across northern Puerto Rico. Elsewhere, expect a mixture of sunshine and passing showers producing minimal impacts. With a predominantly northerly component in the general wind flow, expect slightly cooler daytime maximum temperatures than climatology again today, ranging from the mid 80s across lower elevations to lower 70s across higher elevations. Breeze conditions will continue today, with wind speeds ranging between 15 and 25 mph with higher gusts. The most recent model guidance suggests that a similar weather pattern will persist tonight, with gradually less frequent trade wind showers by Tuesday into Wednesday. This pattern is expected as the dominant deep layer low slowly moves northeastward and away from the region, relaxing the local pressure gradient and, thus, resulting in lower wind speeds but still from the north. The entrance of drier air will add to this scenario, gradually leading to a more seasonal weather pattern. Still, slightly cooler temperatures will continue each day, ranging from the mid 80s at daytime to the mid 50s across higher elevations at nighttime. && .LONG TERM...Wednesday through Monday... A low pressure system located to the northeast will cause a breezy north to northeasterly wind flow to prevail across the local area. Drier, northern sourced air is expected to move in by this time, reducing the amount of showers over the long term period. However, the proximity of an upper level jet on Thursday and Friday will allow these days to be the best time for showers before a drier weekend lies ahead. Northern to the interior sections of Puerto Rico and the USVI should receive the best rainfall due to these conditions. No flooding threat is expected as the majority of showers will be fast moving and isolated. By Friday into the weekend, wind flow starts to become more northeasterly. However, as another trough moves into the Western Atlantic, northerly flow returns by Sunday afternoon, with a bit of a westerly component overnight. Precipitable water values around this time are below climatological average, which is an indicator that any showers that form will be light and it is expected that the northern sections of PR and the USVI will experience the most rain, if any. This pattern of northerly winds with light passing showers will continue throughout the end of the long term period as low pressure across the Northern Atlantic continues to influence a backing windflow pattern. && .AVIATION...Mainly VFR conditions will prevail across most local terminals throughout the cycle, except for TJSJ and TIST, where increased SHRA will result in MVFR conditions throughout the day. Lesser SHRA will affect the remaining airports, but brief MVFR conditions are still possible. Except for TJBQ, where winds will remain lighter and more variable, N-NW winds will persist at 15-20 knots with gusts up to around 30 knots. Locally higher winds are possible near the shower activity. && .MARINE...A northeasterly swell spreading across the Atlantic Waters will maintain hazardous marine conditions. Expect building seas up to 10 feet, and occasionally greater, across the Atlantic waters and Caribbean Passages. As a result, Small Craft Advisories remain in effect for most of the local waters. Beachgoers, A High Surf Advisory and a high risk of rip currents also remain in effect due to expected breaking waves around 6 to 12 feet, mainly across north-facing beaches of Puerto Rico, Culebra, and the northern USVI. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through Wednesday afternoon for PRZ001-002- 005-008-010-012. High Surf Advisory until 6 AM AST Wednesday for PRZ001-002-005- 008. High Surf Advisory until 6 PM AST Tuesday for PRZ010-012. High Rip Current Risk through late Tuesday night for PRZ013. VI...High Rip Current Risk through Wednesday afternoon for VIZ001. High Surf Advisory until 6 PM AST Tuesday for VIZ001. High Rip Current Risk through Wednesday afternoon for VIZ002. AM...Small Craft Advisory until 2 PM AST Tuesday for Coastal Waters of Southern USVI Vieques and Eastern Puerto Rico out 10 NM. Small Craft Advisory until 6 AM Wednesday for Atlantic Waters of Puerto Rico and USVI from 10 NM to 19.5N, Coastal Waters of Northern Puerto Rico out 10 NM, Mona Passage Southward to 17N, Coastal Waters of Northwestern Puerto Rico out 10 NM, Coastal Waters of Northern USVI and Culebra out 10 NM, Anegada Passage Southward to 17N. Small Craft Advisory from 8 AM this morning to 2 PM AST Tuesday for Caribbean Waters of Puerto Rico from 10 NM to 17N. && $$ SHORT TERM...ICP LONG TERM...RC