FXCA62 TJSJ 061531 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 1131 AM AST Mon Feb 6 2023 .UPDATE... Satellite imagery and doppler weather radar showed overall fair weather clouds with limited to no shower activity in and around the islands, as a drier airmass continue to filter in across the region. The TJSJ 06/12Z upper air sounding and satellite derived precipitable water product also suggest a drying trend with the layered precipitable water content at 1.02 inches. Moderate to strong east southeast winds between 15 to 20 knots persisted with very shallow moisture trapped below 800 millibars and still a 2-3 degree cap inversion. No changes to the inherited short term forecast reasoning and grids at this time. && .AVIATION UPDATE...VFR conditions will persist at all terminals. FEW-SCT cld lyrs nr FL025...FL050 with Isold SHRA ovr regional waters and flying area btw PR and the USVI....but mstly SKC. Isold SHRA vcty TJSJ/TJBQ/TJMZ and mainly downwind of the USVI terminals til 06/22Z. SFC wnds mainly fm E at 12-18 kt with ocnly higher gusts between 20 to 25 kts psbl...then bcmg fm E at 10 kts or less aft 06/22Z. && .MARINE UPDATE... Fresh to strong east-southeast winds will continue to promote choppy to rough marine conditions across the regional waters through the rest of the work week. Deteriorating seas building up to 11 feet possible over the Atlantic and local passages, and 4 to 7 feet elsewhere. Breezy to windy conditions will continue with winds between 15 to 20 knots and occasional gusts to around 25 kts possible. The first northerly swell has arrives and a stronger secondary swell expected later in the work week. Small craft advisories and Precautionary statements will therefore continue across the local waters and passages for the next several days. .BEACHGOERS OUTLOOK...Increasingly hazardous and life-threatening surf zone conditions will be likely for almost all of the north and east facing beaches, and possible life-threatening conditions for the remaining beaches the rest of the week. High surf Advisories are in effect, as well as moderate to high rip current risks. Recent San Juan and Rincon buoys suggest breaking waves between 8-12 feet possible for the rest of today. Please refer to the latest Coastal Hazard Forecast (CFWSJU) and Surf Zone Forecast (SRFSJU) issued by WFO San Juan PR for the latest info. && .SYNOPSIS... From previous discussion issued at 447 AM AST Mon Feb 6 2023 This week's main hazard will be the hazardous seas and life- threatening rip currents along the Atlantic Waters/local passages and north-facing beaches in the U.S. Virgin Islands and Puerto Rico. Expect a mixture of sunshine and clouds today with a few quick passing showers. A meandering upper-level shortwave trough will increase instability around mid-week, followed by a building ridge by the end of the workweek into the weekend. && .SHORT TERM...Today through Wednesday... A surface high pressure is currently located over the northeastern Atlantic, maintaining winds out of the east southeast. The winds at the low levels have weakened just a little bit, and breezy conditions are expected to prevail through the forecast period. The most recent satellite-derived precipitable water imagery shows a drier air mass filtering over the region. As a result, limited shower activity is expected today, but isolated to scattered activity will remain possible...early in the morning for eastern Puerto Rico and the United States Virgin Islands, and light to moderate convection developing over western Puerto Rico in the afternoon. The patch of moisture that was supposed to reach the islands on Tuesday is looking weaker in the latest guidance run, but still precipitable water values are expected to climb up to more seasonal values. As this low level feature moves in, the wind flow is expected to shift from the east-northeast. Then, shower frequency should increase across eastern Puerto Rico and the U.S. Virgin Islands during the day, and with another round of showers developing in the southwest in the afternoon. Significant flooding is not expected with this activity, but wet roads and ponding of water in low-lying areas can be expected. On Wednesday, as a new surface high pressure rolls into the western Atlantic, the gradient will tighten once again and winds will pick up, with a steering flow out of the northeast at 18 to 20 knots. At the upper levels, a trough will dig in, enhancing instability aloft. Relative humidities are expected to be higher in the column, from the surface to the mid and upper levels. As a result, the showers could be a little bit stronger with the potential for isolated thunderstorms to develop. A jet maximum is expected to remain just southeast of the islands, enhancing the potential for additional thunderstorms developing across the local waters at times. && .LONG TERM...Thursday through Monday... A meandering upper-level short wave trough and a jet aloft could promote somewhat better upper-level dynamics across the Northeast Caribbean. Once again, GFS and ECMWF suggest a drop in the 500 MB temperatures with values around -10 or -11 degrees Celsius. The jet stream is now (with the latest model cycle) more to the east- southeast of the U.S. Virgin Islands, reducing the potential for the formation of thunderstorms, but the potential remains present. Stability may increase Friday through early Monday as a ridge pattern build at mid and upper levels, promoting dry air and subsidence aloft. At the surface, high pressure will move from the U.S. Eastern seaboard to the Central North Atlantic Ocean, tightening the local pressure gradient and generating breezy and windy conditions throughout most of the second part of the week. This surface high pressure will push a cold front southward but off to the north of the islands (across the Atlantic Ocean), leaving the islands at the mercy of the surges of moisture the wind brings. Consequently, expect breezy or windy conditions Thursday through at least Saturday. The best chance (if any) to observe organized convection through the long term will be on Thursday. Friday onward, the east-to-east-southeast winds will promote a typical rainfall pattern focusing on the activity across eastern Puerto Rico and the Virgin Islands in the overnight and morning and afternoon activity in the west/northwest PR and downwind from the Virgin Islands. && .AVIATION... (06Z TAFS) Issued at 447 AM AST Mon Feb 6 2023 Mainly VFR conditions expected to prevail through the forecast period. Occasional SHRA moving between USVI and eastern PR could through the day, but no significant impacts in operations are expected. Additional activity expected after 17Z, for the western Cordillera Central, with mountain obscuration. Breezy conditions, with winds out of the ESE at 10-23 knots at FL050. && .MARINE... Issued at 447 AM AST Mon Feb 6 2023 The combination of wind-driven seas and a long-period northerly swell will result in hazardous seas across the Atlantic Waters and Caribbean Passages today and throughout the week. The northerly swell will have periods between 11 and 15 seconds, and wave heights between 6 and 10 feet across the Atlantic Offshore and Caribbean Passages. The easterly winds will range between 15 and 20 knots. A surface low-pressure, now moving north-northeastward across the Western Atlantic, will create a long-period northerly swell forecast to arrive late Thursday night into Friday, deteriorating marine and coastal conditions once again. These factors will cause large breaking waves and rough surf conditions along exposed north-facing beaches of the islands. Therefore, Small Craft Advisories are in effect through mid-week and will likely be extended throughout the rest of the week. Beachgoers, life-threatening rip currents are likely across the west, north, and eastern beaches of PR and the northern USVI. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...High Rip Current Risk through late Tuesday night for PRZ001-002- 005-008-010-012. High Surf Advisory until 6 PM AST Tuesday for PRZ001-002-005-008- 012. High Rip Current Risk from 8 PM AST this evening through late tonight for PRZ013. VI...High Rip Current Risk through late Tuesday night for VIZ001. High Surf Advisory until 6 PM AST Tuesday for VIZ001. High Rip Current Risk until 6 PM AST this evening for VIZ002. AM...Small Craft Advisory until 2 PM AST Wednesday for AMZ710. Small Craft Advisory until 8 AM AST Tuesday for AMZ712-715. Small Craft Advisory until 2 AM AST Tuesday for AMZ722. Small Craft Advisory until 2 PM AST this afternoon for AMZ725- 732. Small Craft Advisory until 2 PM AST Tuesday for AMZ741. && $$ SHORT TERM...RAM LONG TERM....ICP AVIATION...RAM